cs126 precept 6: using a debugger

A good java debugger is jswat. (Here's the jswat-2.20.zip installation file that I downloaded a while back; the instructions contained here apply to this version; and newer versions should be available now.)

• Installing jswat.
  • We assume you have already installed the Java SDK. For me, the jdk locates at: "e:\j2sdk1.4.2_03".
  • Extract the contents from the downloaded .zip file. I put the resulting files in "e:\rywang\programs\jswat-2.20". You may put it anywhere.
  • Find a file named "jswat.bat". Add two lines near the beginning of the file. Here is the modified version; and here is the original version.
  • You may click the "jswat.bat" to execute it.
• Using jswat.
  • For any Java program that you intend to debug using jswat, you must use the "-g" flag when compiling the program. See this example.
  • For each program directory, you need to set the classpath. Here are some example class paths added.
  • For convenience, set this option.
  • Click this button to start debugging a program. Here's what I typed in for debugging an example program. (Note I typed in the full path of the .mp3 input file in this case.)
  • Sometimes, the file of interest may not be the file that contains the "main" function that you started with. You may wish to open an arbitrary source file that's of interest to you to perform further operations on.
  • You may right-click a line and choose from several options.
  • You may examine local variables in this function.
  • You may type in any variable names that you're interested in seeing.
  • You may step your program one line at a time using one of several step options.