Getting nullpointerexception, why

Question

Declared:

private Man[] man;

This is the initialization:

Man[] man = new Man[1];

    for (int i = 0; i < 1; i++){
        man[i] = new Man();
            for (int j = 0; j < 3; j++){
                man[i].eatThis(table.foods[table.topFood-1]);
                table.topFood--;
            }
    }

Want to print this:

System.out.println(getMan(0));

which goes to:

public Man getMan(int k){
 return man[k];
}

but I receive NullPointerException. Why? While:

System.out.println(man[0]);

works just fine.

It returns:

Man = (bread, meat, cheese)

Here's the exception:

Exception in thread "main" java.lang.NullPointerException
at ManRunning.getMan(ManRunning.java:80)
at ManRunning.newGame(ManRunning.java:133)
at ManRunning.<init>(ManRunning.java:57)
at RunDevilRun.main(RunDevilRun.java:9)

That happens when you switch them at the same place? – FatalError Mar 03 '13 at 03:40 — FatalError, Mar 03 '13 at 03:40
Is the array man[] still in scope in this function? – Ken Mar 03 '13 at 03:42 — Ken, Mar 03 '13 at 03:42
Any shadowing issues a possibility? – G. Bach Mar 03 '13 at 03:50 — G. Bach, Mar 03 '13 at 03:50

score 3 · Accepted Answer · answered Mar 03 '13 at 03:48

It sounds like you are actually shadowing the class member man with a local variable man. At your initialization

Man[] man = new Man[1];

This declares a new variable. Local variables with the same name as class members are allowed, and they will hide (aka shadow) the class level variable. So, while it looks like you are initializing man, you are in fact initializing a local array and not touching the one in your class. To just initialize it and not declare a new one, you want to say just:

man = new Man[1];

...and of course the shadowing was not as obvious as hindsight reveals it is. +1 — G. Bach, Mar 03 '13 at 03:54

Getting nullpointerexception, why

1 Answers1