Java's abnormal loss

Of course, Java is also flawed place. As a sign of abnormal program error, and it should never be ignored, but it is likely to be easily ignored.

Use the finally clause with some special way, it will happen:

class VeryImportantException extends Exception{
	public String toString() {
		return "A very important exception";
	}
}
class HoHumException extends Exception{
	public String toString() {
		return "A trivial exception";
	}
}
public class LostMessage {
	void f() throws VeryImportantException{
		throw new VeryImportantException();
	}
	void dispose() throws HoHumException{
		throw new HoHumException();
	}

	public static void main(String[] args) {
		try {
			LostMessage lm = new LostMessage();
			try {
				lm.f();
			}finally {
				lm.dispose();
			}
		}catch(Exception e) {
			System.out.println(e);
		}
	}
}

Output:

From the resulting output, we can see: VeryImportantException disappeared, it was replaced finally clause of HoHumException.

This is a very serious drawback, because exceptions may be lost in a more subtle than the previous example and shown in imperceptible ways.

 

An easier way to lose abnormal return from the finally clause:

After running this program, we can see that even if an exception is thrown, it will not produce any output.

public class ExceptionSilencer {

	public static void main(String[] args) {
		try {
			throw new RuntimeException();
		}finally {
			return;
		}
	}
}

thank you all!