当我无法使用调试器时，如何以字符串形式获取错误消息

Question

I want to be able to save an entire error log to a String in java. For example, if I have the line

int a = 0/0

then this gives the following error message in a debugger:

Exception in thread "main" java.lang.ArithmeticException: / by zero
    at HelloWorld.main(HelloWorld.java:8)

What I want is to be able to have this above error message entirely in a string. I've tried surrounding the code I want the error string for (for this example, the division by zero) in a try/catch block as follows, but this only gives me the java.lang.ArithmeticException: / by zero portion of it.

This is my try/catch block:

try{
       int a = 0/0;
   }catch(Exception e){
       String a = getFullErrorString(e);
   }

With my method being:

public static String getFullErrorString(Throwable error){        
    return(
            error.getCause() == null ? String.valueOf(error) : (error + "\n" + getFullErrorString(error.getCause()))
            );       
}

I need to do this because my app does not work with a debugger and an external device at the same time (the external device uses the USB-C port so I can't debug with it plugged in, and Bluetooth is not an option because my app makes heavy use of Bluetooth). Please help!

Answer 1

Here is a class I find useful for catching and logging exceptions:

        String rootDir = Environment.getExternalStorageDirectory().getPath();

    //----------------------------------------------------
    // Define inner class to handle exceptions
    class MyExceptionHandler implements Thread.UncaughtExceptionHandler {
        public void uncaughtException(Thread t, Throwable e){
           java.util.Date dt =  new java.util.Date();
           String fn = rootDir + "/YourFilenameHere_" + sdf.format(dt) + "_DBG.txt";
           try{ 
              PrintStream ps = new PrintStream( fn );
              e.printStackTrace(ps);
              ps.close();
              System.out.println("wrote trace to " + fn);
              e.printStackTrace(); // capture here also???
//              SaveStdOutput.stop(); // close here vs calling flush() in class 
           }catch(Exception x){
              x.printStackTrace();
           }
           lastUEH.uncaughtException(t, e); // call last one  Gives: "Unfortunately ... stopped" message
           return;    //???? what to do here
        }
    }


    Thread.UncaughtExceptionHandler lastUEH = null;

// Then in onCreate:
        lastUEH = Thread.getDefaultUncaughtExceptionHandler();  // save previous one
        Thread.setDefaultUncaughtExceptionHandler(new MyExceptionHandler());

The stack trace is written to a file.