问题
I have a large (legacy) application that I have to make a fix in, with terrible code structure and so much code smell that I'm choking. I can't really figure out where a string in the gui is populated. Therefore it would be nice if i somehow could have an expression/breakpoint once ANY string (I don't know the name of the variable, or where it is) is equal to "foobar" so I can backtrack from there.
So, what am I looking for? :)
回答1:
This trick works as long as the string that you want to find isn't hard-coded in any way. If the string was getting passed to the compiler, then this trick may not work.
- Ensure you have installed the source-code alongside the JDK.
- Open
java.lang.Stringclass file. Your IDE should be automatically show the source-code for this class. - Put a breakpoint in the
char[]field variable. The variable name may vary for each JDK. On my machine it isprivate final char value[];. Put a condition on this breakpoint, e.g.:
value!=null && value.length==6 && value[0]=='f' && value[1]=='o' && value[2]=='o' ....
Please note that the performance will be slower due to this breakpoint.
I have tested this on a simple application that read the string from a file, and the breakpoint is being hit properly when the file is being read into a string.
回答2:
If you don´t know where the String gets populated, but you do know where the variable it is in is, you can place a watchpoint for the variable. A watchpoint is exactly placed as a breakpoint, but in the line where the variable is defined.
This watchpoint will pause the programm everytime the variable is changed or read.
回答3:
IF you have an IDE, such as Eclipse, you can set getters and setters for all your variables then, from every one of these setters, call a function called "checkValue" for example, in this "checkValue" make a conditional breakpoint for the specific value you are looking for.
This will require code to be changed, but as a by-product, would create a cleaner code.
Use jmap and cause memory dumps. Inspect every dump for the value you are looking for
Use Introspection and cycle through every variable, looking for the value.
来源：https://stackoverflow.com/questions/24135716/eclipse-conditional-breakpoint-break-at-any-string-equals