---
title: WWDC2004 Session 639
framework: wwdc
role: article
path: wwdc/wwdc2004-639
---

# WWDC2004 Session 639

## Transcript

Kind: captions Language: en happy Wednesday thanks for coming i'm not actually speaking in this session i just wanted to give a quick introduction my name is Matt rants I work in DTS and I'll be coming back at the end of the sauce to talk a little bit about DTS what DTS does in case some you don't know about it but I just wanted to introduce you because I think that this is probably the most useful java talk this week that as far as you guys are just turned aside from mine tomorrow but when you guys are out of here in an hour and a half you're not going to go read any documentation or download anything at the end of the day you're going to know everything we know about debugging analyzing unerring java applications on the mac and i think that's something that a lot of people been waiting to hear about so without further ado I would like to introduce Tom O'Brien from the product engineering team Thanks you're in the right talk if you're a Java developer who wants to deploy or Java on Mac OS 10 but you want to find ways to avoid cross-platform platform compatibility issues that you might run into or if you want to know ways to isolate problems that you find running java on 10 or report problems back to Apple when you think it's apples blog so how are we going to approach this the talk is going to be in three parts today first we're going to show you coding techniques and tips for getting the best cross-platform behavior out of Java second we're going to show you testing and bug isolation techniques that help you find problems using the tools available to you on Mac OS 10 and third we're going to tell you how to write an effective bug report so let's get started with the first section Java is positioned as a cross-platform development and deployment environment and that's true and its catchphrase is write once run anywhere everyone has heard that but in the finer levels of detail the platform independence isn't an automatic thing that you get for free your application may run great on one java implementation on one platform but the same code running on another platform may run well but not in the exact same way at the finest level of detail you may not even be aware of all the areas that have subtle differences in Java implementations we're going to highlight some of those today how we're going to approach this well first we want to have you thinking about in a slightly different way we want to show you the tips to get the best cross-platform behavior out of your code and the things we show you today are applicable to all Java implementations even though we're going to be focusing on Mac OS 10 we're not trying to do it in a platform specific way we're trying to show you general techniques that allow you to run equally well everywhere without doing something platform specific if you can help it will help you be aware of the areas where different platform implementations can differ so that you can adapt to those differences or again design and apply form neutral way so that you don't have to adapt so let's move on to an example the anti-aliasing settings for text and graphics vary from platform implementation to a platform implementation and in fact on Mac OS 10 for applets in the browser users can set whether anti-aliasing is on or off as a preference so it varies from run to run so you can't guarantee that it's on or off in any particular situation here just to remind you here's here's the same code drawing alias and with anti-aliasing on you notice that line rendering gets much smoother in the in the image on the right but it also changes the appearance and this may matter to your application so what should you do if it matters to your application you should set and check the anti-aliasing settings explicitly rather than assuming that they're on or off here's how to deal with it for text only and this is using standard sun java 2d api's to deal with the rendering hits here's how to do it for both text and graphics and these are just again standards on api's in java 2d moving on to a more specific example for anti-aliasing for text the in the swing aqua look and feel on Mac os10 text anti-aliasing is on by default and this is in order to fit in better with the other mac OS 10 applications and match the mac OS 10 aqua guidelines it improves readability of text at small point sizes but text metrics likely to be different between alias and anti-alias text me see here this is the same code running with anti-aliasing on and then off you notice that not only does the appearance of the text change but the length of the text changes and so metrics that you gather with the setting in one in one position aren't valid when you switch to the other position so how do you do with this once again check and calculate things rather than a hard coding or assuming here again is a standard Sun API for dealing with in this case calculating the string length of a particular string rendered in the current rendering context with a particular font and this tells you how long that string is going to be right now it's referred to as width of course because its graphical but we think of it as string length so you can find out how many pixels wide that that string is going to be right now when it's rendered on screen and deal with that appropriately if it matters to you moving on to other metric tissues control sizes for java implementation widgets vary across platforms the same controls rendered on Mac os10 using the same code running on other platforms don't have the same appearance the same font the same size and this is a this is a standard platform this is that this is a standard change that happens from one platform to another that is intended to fit in with the platform look on that particular native platform but it makes it fragile to hard-code widget and font sizes that you where you've gathered information based on the behavior and metrics on one platform so how do you deal with this once again there are api's that let you check rather than hard coding based on what you've measured on one platform for widget sizes the Sun API to get the preferred size of a component is relevant here for fonts you can find out you got back for a particular default font and you can find out the metrics for that font in the current again in the current situation in the current rendering context and deal with it and we already showed you how to calculate the string length in the particular rendering context Etrian right now with the particular font you're running with right now a more general approach for dealing with the fact that you I metrics vary among different implementations of Java is to use a layout manager the layout manager will arrange the UI for you based on the situation that's happening on your platform right now it's as an additional benefit if you're even on just one platform of handling what happens when you localize strings to other languages they tend to change length look like an English into other languages often tends to make for longer strings that may not fit into six bounds that you've already picked and the layout manager will deal with that gracefully for you in order to discover there you have whether you have successfully made your code metrics independent and possibly deal with different platforms you should try your code out on multiple platforms if you are using this if you're using this example here this is something that's running in the Java implementation on Windows and if used the same cup and and hard set the window size based on what we measured that it fit into on Windows you notice that the button and and even more the label at the bottom are clipped because those don't fit in the look on Mac os10 however if you use a manager and unpack it all fits in nicely and looks great for more details on the layout manager you can go to the Sun website and and pick up more information about this and other topics another you I thing that varies between Java implementations and is especially important on Mac OS 10 is that the window resize user interface is in a different location again in order to sit in with what fits on that particular platform Mac os10 the resize box actually takes up space in the window content region in the extreme lower right-hand corner and that's intended tile in with the scroll bars that are normally on the lower and right end edge of the window for Java code that's coming from other platforms that may end up covering up content that's an extreme right hand corner of the window you notice in the sample application the extreme right hand button root of x by the resized box so how do you do with this well there's several different approaches general approach would be if you didn't crowd your life there was so that the extreme lower right-hand corner of the window is important you may open up your UI and make it look cool anyway that may fit in with what you plan for your application if you're using a layout managers we suggested earlier you may have to use an empty place holder component pulled out space underneath the Grove in order to make this work another alternative on Mac os10 is to use this Mac os10 just hide and show the grow box for it to make sure that the grow box is showing or not showing it doesn't change the resize behavior of the window but it does it does determine whether the grow box is actually drawn on screen and here's the same code which earlier with this property set to true the default and fall the window is still resizable but now you can see that this may end up in one of the cases where you actually have to hard code something for a particular platform there any situations where there's no way you can design your code entry platform neutral bay if you really have to do something special for mac OS 10 1 emphasized that you want to do that if you really have to it's it's kind of a last resort thing you really want to I defining the platform neutral way if you can but if you have to this is the way to deal with it on excess 10 the right way you want to get the OS name system property lowercase it and then find out whether it starts with Max is OS based set Technic 2110 has more details about about this approach again I want to say that if there are AP is to get at specific metrics you want to deal with those AP is you're interested in specific behaviors or metric on that flat for those specifically rather than trying to infer them from being on Mac OS test things may change from one implementation to another or in some cases it may even take to another as we saw earlier so what do we dealt with the ways to design code and from neutral way and the way you can firmly designed in the platform neutral way is to describe your coat on multiple platforms with your topic this top you discover inadvertent some dependencies in addition to the metrics issues we were talking earlier there's that you may be inadvertently depending on that you don't know up to trot for example if on a petition there are special implementation that certain things to be accelerated for rendering modes for graphics primitives your application ntage of that special character rip and run great platform but I'm turistic isn't it or applicator and the way to find that out prog it out specific to recap the move up you want to get and text anti-aliasing settings rep or off matters to your application you want to check in the current situation hard coding them big platform or on a previous rough if all same platform specific we should & Co is ten there right I'm them lasane who's going to show you punjab khatam good afternoon welcome talk about two things it's Spock first I'm going to top of Jay yet how you can integrate about the u.p price problems it's Java start with oh all right forget this problem day unit how many people out here know what dig in it is aa recorders with guardian that's great we know what day it is it's an open frame incorporating unit to make some a natural to the developed in documents and their their low over by which I mean they don't get it away so let me sleep devil of unit into Xcode here i have this is an aunt and an expo template recently made available and it's available on both tiger and Panther you do that is to me prop so the father hears is just my application about it for Jane it next but I have a test message in a test and it things about it one is here you can see I import in it framework and getting my classic did I look me even open today in a test however you you know integrated as you packed it and that's where the real holiday in it from dana dragon install it in a glass hat be important so in my bill Tupou add a new target a tete in i can go into detail up this is all paper and then backed up a little in my dark or gate make it depicting the test target I thought I had I can put it bring it up higher sure I have a house it responds to for that for that code quick onion the output in Xcode currently the out from aunt Tabitha over pain so the filter window and if you notice the lower paint has a slider and let me just met up so you can see you click compile target bunting I've already suspect and then chick font size on this at least I don't know where the set you have to look so as to what you can see sues the output from the test it might be nice out in my building xml tells you what test suite is running and then there's summary here from in it it does it ran three tests and one of them failed there's a list of tests following that the last one table then the output from the failure of which you can read netten a step crawl from the point of failure so let me move over to my test code which is in my test file the name of the failing method was test for small failure and i used a its method cert true to a skirt too and for purposes of the demo i said that to fall so that we would get a failure i'm going to change that to true and then I round again and you'll see a little bit different figure again this time you can see in the compile in the compiled project it actually does compile because I changed my my test case and here trying to run in the test in the Test section you can all of the tests you man and always have to pass and because the test pass it was able to connect to the jar section and then execute the code and here's location running where we show the alias person completely effects which you saw on a previous slide so that j unit running inside xcode on Mac OS 10 select slice so the things you need to do one you need to write tests you've got to write tests in order for them to run number two you need to get a copy of j unit and put it in your classpath in your machine on the demo machine I put mine in library Java extension so it's lots of different ways to add to your class path and then third you need to modify your build XML file to execute day unit and this screen you see a very simple yeah minimal way of executing j unit tests and then here I've added one more argument to the j unit command the halt on failure argument and it's all fun failure is set to yes then when you build with your aunt project if there are any test failures then it will stop at that point you will get a failure and it will not go a lot you know your bill will be considered to a fail you said that to know it'll run the test that will go on and build and run oh and again it's your choice the way you design project whether you want to set that true or false I'd recommend true down at the bottom you can see just the beginning of my jar target and it you the the default template for aunt for aunt based project to the Pens clause set to compile as a lot effectively depending them on test so that it would execute the test as part of building the pipe so that's in it pests are integrated into your development process you write your tests it's it's a really nice way of integrating kept seeing into your development process see it works really great with code I've been using it for a while now other IDE a cliff I also support J unit it's a platform with a large active community most of you raised your hand so you already know a lot of this and for more information go to j unit org and read the documentation there so the other part when things go wrong sometimes problem in your code sometimes it's underneath you sometimes it's out of your control and I'm going to cover both of those there is so I'm going to cover sub things i will show you some mac OS 10 tools for isolating problems these many of the tool well some of the tools are specific to Mac os10 many of the tools are cross-platform tools you may already be familiar with I will mention when when i'm using a tool that's crop platform just so that it's clear and the goal is to give you the knowledge you need to fix the problem or if the problem is outside the scope of your code in order to isolate it and to report an effective bug so let's go to a demo again now i'm going to do a little bit of role playing here i am a developer fairly new to mac OS 10 and i'm starting to bring up my projects on on the mac and top here tom is the expert and I'm going to be calm let me get this stuff out of the way okay um I've written a little simple program it does some painting it has two types of threads and both red paint to the screen and it's supposed to be in between the two threads but but it doesn't animate it's just sitting there so you know Mac os10 what should I do here why don't you try activity monitor ok let's try activity monitor a thread painter there's my thread painter so what am I looking at this is showing you the state of all the processes that are running for you in excess and there's thread painter and it looks pretty quiet it's using no cpu or essentially no cpu so your application is basically stopped okay so i can tell my application doesn't seem to be doing a whole lot down here there's not happening so let's find out more about what's going on inside inside java right now if you send a kill minus quit signal to that other process the vm will dump the state of all the threads of the run ok so i guess i need terminal stefan big enough can you guys read so tip- quick this is standard on unix platform if i kill a quit signal it's obvious the process ID which i can see here is 629 it should dump a stack trace out to stand it out but Tom I don't see anything well how'd you watch hmm how did you launch I double-click the jar and the finder ah it's going to end up in the system console so go look on the system console ok let's take a look at 15 console here wow this looks kind of like a stack thread dumped here ok look I see this is some old debugging output from my application the computer and oh yeah kicked my drawing thread here's my even drawing thread ok it's possible you have a deadlock the vm will catch simple bit locks aren't you look down at the bottom and see if it has anything to say down at the bottom ah found one Java little deadlock sure enough it looks onto good luck in my code let's take a look at my code thread p nerd Bob a line 70 I'm going to open up thread painter next click here go to line 70 and there's my odd thread and there's my even thread and I've synchronized this even thread it's an outer lock and lock and mm-hmm I have an inner pocket now blocks on the odds red looks like you set up a classic good luck hey did you do this deliberately Oh what do you think actually you know usually it's not quite this straightforward but you get the idea the school how to use the tool to end this type of problem go back to slides so the tools of yes you you thought kil- quit useful activity monitor and kill minus quit kil- quit works cross-platform if you're running in terminal if you're if you're executing from the command line you can also do control backsplash and get the same information going to machine you can do control break and also get to the same information so up on the screen the little sample you see I use top to get the process ID and kill minus quit for that process ID to dumps with the spectra and it pointed out one of the slight Smith's of confusion especially for people new to the mac OS 10 where does the output go running in terminal as you would expect the output goes to the terminal where you right where you are but if you're double-clicking a jar or if you have a dot a passed app application in the finder the outputs we go to system the system console console that app and similarly if you're running in Safari you have an athlete in Safari the outlets going to go to console as well unless you have turned on the Java console using the Java setting plugin or the Java settings application in which case the output goes to the Java console which also has some other debugging tools that you can take a look at there's a help screen that shows up when you first invoke that console useful for debugging assets lastly if you're running if you're executing your coat from from Xcode you'll see the output right in the run log okay so let's go to another time same role I'm a developer still getting getting my sea legs here on Mac OS can hide some of the stuff so it's not distracting and I have another little application I called drawing loop and it does some animation this time it does do animation see it's working and I can turn on not the box numbers we teach square has it has a number associated with this slider the J slider down here at the bottom but Tom I have a problem here when I drag it all the way to the right it just kind of stopped responding and then if I resize it gets even worse and there's that there's that rainbow cursor so I just thought activity monitor what's the last one and I can remember these things i'm going to i'm going to look at activity monitor again and see what it tells me so here look at this it's very helpful actually drawing loop is hung its activity monitor at least thinks my application is hot and i'm using a lot of cpu so so now what should i do should i use kil- quit again get a sec don't we find out what state the java threads room but we haven't even cooler tools with this its new this week it's shark for java that's right so the launch shark I was acid the vm performance talk yesterday afternoon when christie demonstrated shark so I do know a little bit about shark now because I just a demo so let me try it with my application so there is one piece of setup you have to do in order to use shark and you might have seen it in some of the output in fact I think in the console it'll still say it right here picked up Java options I have set dash X run shark in order to give shark the data that it needs from the Java Runtime to for it to do its magic so chalk is a profiling tool you can use it to isolate bugs I'm just going to do a time trace here and i'm going to start it and it's sampling what's going on in my applications there in the background the one with the spinning rainbow cursor and now let me stop and it will produce this nice report so this tells me where where I was when shark was sampling my application who we're on spending time and it's a very top you see surface data finished lazy drawing no it's not probably not very readable this one one at the top is is the one where the most time is being spent where shark sampled the most the most time so I'm just going to open it up and see what I can learn from here this is a stat crawl the leaf is at the top and as I drill down you can see I spend a lot of time in a WT which was called by Java 2d and then I get down to these blank ones here but you know I recognize these drawbacks silk screen or X paint as my code that's my code executing their shark knows about Java the other tools that you may be used to using such as sampler or sample on the command line they don't have this kind of intimate knowledge of Java now paint silkscreen with Rex Rex I want to go take a look at my picker team and Tom maybe you can help me because you're an expert see if there's anything here I'm doing that might be causing that rainbow cursor there's my paint method right here down at the bottom Barry you want to tell me what extreme count military oh yeah extreme count mode yeah you know i just recently added that when I drag it to the right it spoke to fill the screen with rectangles and that's actually likes your full screen it's wrecked and maybe I set the bar a little bit too high this is a dual processor t5 it can handle 10,000 runs of 10,000 rectangles campus eventually eventually yeah actually this is not hung even Activity Monitor said it was on it would eventually return but it would take a while and I said it such that it would take a while usually not that straightforward so back to slides here you saw again activity monitor the CPU what level was really high that time so you did get some interesting information from Activity Monitor you could have used top in that same situation and seen similar similar data and top is cross-platform at least four other UNIX machines and i showed you shark a great tool recently enhance to to tell you a lot more about java and there's a shark talk this friday i'd like to tell you about and you should go christie is giving the talk and that's at three-thirty and i don't know the room name but accession number three up 70 sanjay and nathan are giving the talk okay and in bed the talk is not specific to java but the techniques that you learn there should be useful for java as well so did I did I go back to demo okay this is my last demo you just hide some stuff here oh and so here's a little tiny tool little tiny technique if you hold down the mouse on the icon is force quick comes up as an option if you don't see force quit you can all down the option key to force force quit nice way of getting rid of here frozen out okay my last appt here tom J&I rapper jar this is a little piece of java that calls a little piece of native code so i can bring it up here and when i click on this button at this point it will call my native library that i've written and it crashes so what should i do should i should i click submit report here and slim the bug to apple hold on hold that thought locate we'll come back to that just put that aside alright remember that out of the way here so what should i do with this application well you said who was it was needed code that you're calling yeah well we probably if you don't have source available to you your your best debugging tool that you have available would be GD be so once you try attaching to it in gdb before the crash that actually brings up a very important point sometimes you do have source have xcode is the way to go single step and xcode tracy's but there are lots of different situations where you might not have source you might have a third-party native library you might be on a customer's computer trying to do debugging with with what's there you might be on a test machine in your lab lots of different times you won't have source and so you want to use other tools that are available to and you said gdb I know GDP so let me launch the app here I'm not going to press the button yet i'm going to use top this time see what process it is it looks like process 654 copy that and i will do a GD be attached not going to teach ugtb i'm just going to show you a tiny bit of gdb being aware that it's there and that it's useful is is the main point here gb is now attached to my process i'm going to tell it to continue so that my application has control again and now i'm going to press this button and you can see gdb immediately catches the crash so here i can do a thread apply all back-trace yes there are shortcuts for this and now i have a dump of all of the native threads that are running associated with my application many of these are java threads like the event thread but at least one of them should be my code and go back up to the top here it looks like could not access memory on thread Oh xf6 03 and that's right here so it's planning to line 29 of my of my code so plan on doing on source code this time we do so we're just going to take a quick peek at my little Jay and I lied and we will go to lunch 29 Xcode and here tom well it may be fairly clear to you but here I have a pointer and I'm be referencing it but oh look just above here the pointer got set to 0 how could that have happened yeah that could be a problem and if you've ever debugged z-code you probably know that it's not that straightforward usually sometimes it is some time to do so why do you want me to set this window aside here well the submit report button has hiding behind it a something very similar what you just got in gdb which is a native fresh report showing all the native threads that were running at the point of the crash including a little bit more helpful stuff telling pointing you to the exact thread numbers that crash so it's containing bit yes the same information you got and you sometimes get this if your application has a user interface that's the basic rule that you'll get this crash report window and you can copy and paste this information into a bug report or you can use it for further isolation on your machine so now i can send them to Apple sure go ahead well you know I just reported to Apple my own bug so you probably shouldn't do that hip is if it's in your own code let me point out sometimes you'll you'll get a report somebody has my application crash and you said well did you grab it the stat column they say no those fat calls are actually saved on your machine and in this case it's in my home directory in library logs and inside crash reporter you see a java dot crash log file this contains the log that you just saw on the screen for all of the clashes that have ever happened for this user on the system and you may have noticed as I was navigating here I went past a folder full of a bunch of Java native crash logs and they have a PID associated with them if I look back here at my gdb output process 654 was the one that had crashed and so that would be this one here at the top and let's just take a quick peek at that if you're reporting bugs this this file can come in handy in isolating where the problem is in this case you see here this is a java stat crawl from the point where it crashed and up near the top we were in java and it at the very top it called a native method so that's the point at which it kind of jumped out and left Java and that's both the limit of the information in java the java vm can give you about the crash there's also a little helpful reminder here at the bottom and this is this is helped reduce some of the bug reports we get it says the exception above was detected in native code outside the vm so and usually accurate maybe not always but what usually means is it wasn't Java crashing it was something else crashing it may have been a native library that you had written it might be an OS beggin may still be something that you'd want to report I just wanted to point out that little little detail ok back to slide guess the font could be a little so what tools did we use their GD be attached gdv cross-platform handy tool we use the class reporter to window as a as a bug isolation tool and you saw where I had found some of the crash logs in my library logs folder so what have we learned here this is a summary first in the first crash demo or in the first hang demo I was spinning the CPU is low i found that out by looking an activity monitor could have used top PF similar techniques for finding that out i did a kill minus quit to get the information control backslash also works in the second in the second example i had high cpu usage which i saw from activity monitor and in this situation we use sharp you don't have shark you should download it you want to get the latest version of shark both for tiger and 4p answer the download is available on developer apple com tools / performance don't have it right okay and you could use kil- put in this situation you would get some information that may help isolate it the date detail that you get from shark is a lot there's a lot finer grained a lot more detail a lot more useful and then the last example the crashes in native code we use gdb we offload the crash reporter and the java logs as you just saw but there's one more thing relative to that last one what if it crashed and you didn't have a native library what if there was no native code on your side so it was pure java well pure java shouldn't crash right not supposed to crash so sometimes you find a bug in Java or perhaps in the OS below that so what you do in that situation well you probably want to get working right away so the first thing you would want to do is find a workaround or maybe see if you can get by without that specific piece of functionality a very active developer community out there of the java dev mailing list is the best way to get in touch with that how many people here are already on java dev little less than half highly recommend java dev you should sign up lists of apple com it's a free mailing list and very active community they can often help you find work around Apple engineers are on there don't consider writing to Java Doug of being the same as logging bug report and if you do get a crash we do want you to file a bug report we don't want you to just file like any bug report part of the reason we're giving you all these tools and techniques is so you can file a great bug report which leads me to the last part of the talk where tom is going to tell you how to do such a thing click thank you so when you find a problem that you want to report to Apple the best way to get that information to Apple is to log a bug report Apple's radar databases the way we track hardware and software issues that that come up and and the best way we track at software issues that hardware and software issues that come up as Apple developers your way into the radar database is through the bug reporter web page that Barry just mentioned he also talked about sending email to java dev so you can find a workaround or discuss your problem with with other folks Apple engineers are often present there but their presence isn't the same as filing the bug so you you need to use the official mechanisms to get your bug report back to Apple the crash report window that we just saw is intended mostly for end-users so we saw how we could use it to find out more about isolating the problem but just clicking send reports Apple is intended as an end user technique you guys have more powerful technique some of which we showed you in order to isolate the problem further in better ways so what's in a good bug report there's three major areas that characterize a great bug report a good problem description clear steps to reproduce and technical information that gives the context for the problem that you found we're going to go through each of these in turn first the description of the bug the bug that you found is a summary of what happened first what you expected to happen and then what actually happened and if you have to explain why you expected what what you expected to happen you can you can spell that out to which you want to contrast those two things so that we know what you're really expecting this is a modified excerpt from a real bug report you notice the developer has summarized the problem by by setting forth what they were doing and what they ran it what problem they ran into and you also notice that they referred to a screenshot which is an invaluable piece of information in bugs that end up being graphical because it really does tell the story great in a great way the second component of a great bug report is clear steps to reproduce you want specific step-by-step instructions that a naive user could could could use to reproduce the same situation you ran into with little or no knowledge of your product or your particular problem domain if those steps don't always end up having the problem that you ran into you should indicate approximately how often it takes to run through those steps and hit the problem again another excerpt from a bug you notice the developer has spelled out numbered steps of what you should do in pretty clear language and has also contrasted with that with what the computer was responding with and a common way to do that is to use an ascii art arrow but there's plenty of other ways to make that clear the third area for context of the problem that you ran into is the technical details and this breaks down into some further three further sub areas that will go through first more detail about the failure we saw how to capture crash logs and in most cases both the Java and the native stack crawls are important here for crashes that you run into in Java in the cases of bugs that do or don't involve a crash any exceptions or messages that end up in the console leading up to that problem are also useful in isolating the problem further and show you should include those and we saw that for graphical issues the screenshot is an invaluable piece of information in spelling out the story of what's going wrong the next sub component of technical details is the software configuration that you're running on the mac OS 10 version you found it on the Java version you were running with both of those in detail and if it only happens on some Java can some Java versions or some Mac os10 versions spelling those out and saying where it doesn't doesn't happen is useful in isolating the problem further additionally if you have access to Java implementations on other platforms contrasting the behavior of the same steps or the same test case on those other platforms is is also useful in tracking down the problem further in the special case of Swing bugs saying whether the problem you see happens with the Aqua look and feel or with the metal look and feel or both of them is useful information because those are two different implementation paths and another excerpt from a bug report summarizing the software config you notice to develop a detail of the Mac os10 and java versions they've regressed with a previous version of Java to to say whether it did or didn't happen and they've even compared with Java on another platform the final subpart of the technical details is the hardware configuration and this is kind of the answer to the question when somebody says what kind of machine you have and so it's the summary of you know I have a g3 g4 g5 the clock rate whether it's a single or dual processor machine the next most most Java bugs are not hardware dependent but after CPU dependencies the next most likely place to run into hardware dependent bugs in Java is in the graphics configuration and so we're interested in knowing what graphics card you have how much vrm there is what resolution you're running in and whether you have multiple monitors configured if you have any really unusual devices attached any odd serial devices that your application depends on or you think might be relevant to the problem you should spell those out too especially if you have J&I code happens to be talking to them that might be a clue here's the hardware configuration from an example bug you notice that they've compared it with a platform where it doesn't occur and you develop notice they've also referred to the apple system profiler information that they captured the apple system profiler can do kind of a brain dump of the entire configuration of your machine down to really fine levels of detail most of which aren't usually relevant in Java bugs but you never know so it doesn't hurt to throw it in but it's also useful just to have this brief summary of your configuration that I described with a cpu type and monitor configuration and and other basic things like that now we're into the fourth part of the three that I originally promised the fourth part is great bug reports have a test case a test cases self-contained steps to reproduce your problem if we have a test case it means that Apple knows that they're trying to reproduce the exact same problem that you originally found because they're running the same test case that you ran to show your but ideally your test case shouldn't require user intervention that's not always the case but if your test case can discover whether the bug is present or not all by itself that's really great a test case that can be run from the command line that's been whittled down to a simple public static void main test or is in the form of a J unit test is is a great way to present that and if you have a J unit test that can determine pass or fail all by itself it may end up being put into our regression harness internally so that we run it periodically on upcoming builds of Java and your test case will live on in immortality here's a reference from a real bug you notice that the person who originally filed a triangle bug referred to a test case so let's recap what what's in a great bug report first a clear description that contrasts the actual and expected behavior second simple steps to reproduce that a naive user could could go through to get to the same situation that you originally ran into finally technical details the crash logs that we showed you how to gather earlier any messages to the terminal or console any exceptions are useful to include and the configuration information that we broke down hardware and software configuration comparisons if you have them with other versions of Java Mac OS 10 or even on other platforms and the single most important part could be the test case the self-contained steps to reproduce your problem the guarantees that we're talking about the same bug that you are getting back to the triangle bug the triangles Drudge is fine now in case you're worried so where we been today we showed you techniques for doing platform neutral java coding when it's possible using the api's that are available to you in from some java that allow you to have your code work flexibly with java implementations on multiple platforms and and work great we show showed you some bug isolation techniques for finding and isolating problems further when you run into them running java on mac OS 10 and we showed you how to a file an effective bug report to get information back to Apple when you think you found something that Apple should be aware of now I'd like to bring back Matt grants who have some additional points well thank you very much Tom so there have been a couple questions floating around this weekend in weeks past about DTS and what DTS does and what DTS stands for how many of you have actually logged and into it with DTS in the past okay that's pretty good crap so DTS is developer technical support and I'm going to just reiterate what Barry and Tom said is that you know the java dev mailing list is a priceless resource there are both apple and non apple experts on the list that replied very frequently and very very rapidly sometimes too much frequently I think in most of the incident and most of the sessions this week we've been telling people if you join java dev set up a filter because there's quite a bit of volume in it but a lot of the information is very very useful and if just community conversation doesn't help you out you can talk to DTS and send an email to DTS an apple and what DTS does is basically we give people code level assistance on a per incident basis or a per problem basis and that could be something as simple as hey I read about this new API or this new feature I don't know how to implement it can you guys help me understand how this works or it could be i have this bug and i don't know how to work around it and it's critical to my application we do anything in between or including those two things now the reason I'm emphasizing this is because DTS is not actually fix bugs in the JVM or in the OS anywhere else engineering works on the bugs and DTS works around them and I wanted to emphasize that because sometimes we get people writing in and saying okay I bought an incident will you fix my bug now please and that's not really how we work we'd like to think that we fix your bugs even if you don't pay us but some people out there may be more skeptical that's really the only message i wanted to send DTS is out there there are people for java there people for printing core graphics sound quicktime every technology area i think that's about it so of all the things we've been referencing this afternoon there's obviously the disk image that's been showing up for every talk this this week there's the java reference library off of the reference library home there's a great document on general java 14 development for mac OS 10 which talks about cross-platform issues as well as things you can do to enhance your Mac look and feel and there's the tech note that was cited earlier number 21 10 for identifying Java if you need to do something Mac specific the best way to identify Java on Mac OS 10 as well as identifying a specific job of release on necklace 10 that has version strings and everything