Why does Java allow for labeled breaks on arbitrary statements?

Question

I just learned today that the following Java code is perfectly legal:

myBlock: {
    /* ... code ... */

    if (doneExecutingThisBlock())
        break myBlock;         


        

Answer 1

The issue with goto is that it can jump forward, past code. A labeled break cannot do that (it can only go backwards). IIRC C++ has to deal with goto jumping past code (it is been over 17 years since I cared about that though so I am not sure I am remembering that right).

Java was designed to be used by C/C++ programmers, so many things were done to make it familiar to those developers. It is possible to do a reasonable translation from C/C++ to Java (though some things are not trivial).

It is reasonable to think that they put that into the language to give C/C++ developers a safe goto (where you can only go backwards in the code) to make it more comfortable to some programmers converting over.

I have never seen that in use, and I have rarely seen a labeled break at all in 16+ years of Java programming.

You cannot break forward:

public class Test 
{
    public static void main(final String[] argv) 
    {
        int val = 1;

        X:
        {
            if(argv.length == 0)
            {
                break X;
            }

            if(argv.length == 1)
            {
                break Y;   <--- forward break will not compile
            }
        }

        val = 0;

        Y:
        {
            Sysytem.out.println(val); <-- if forward breaks were allowed this would 
                                          print out 1 not 0.
        }
    }
}