Can I use value of a local variable defined in a method, in other method in Java?

Question

The method is not returning the value of the local variable.

Can I use the value of local variable index from the following method

public boolean contains(Object input) {
    int index = 0;

    while(myAsetIterator.hasNext()) {
        index++;
        if(input.equals(myAsetIterator.next())) {
            return true;
        }
    }
    return false;
}

in this method as the index of the array of the object that I want to remove.

public boolean remove(Object o) {
    int count = 0;
    if(o == null) {
        return false;
    }
    if(contains(o)) {
        genArray[index] == null;
    }
    if (count > 0) {
        System.out.println(count+" same elements were present in Aset. "
                + "Removed all those "+count+" elements from Aset.");
        return true;
    }
    return false;
}

I know the scope of a local variable is limited to the method it's declared in. But there might be a way that I might not now yet to make this happen without using a field/instance variable.

I'm afraid you can't get the local variable value. You may look here : stackoverflow.com/questions/6816951/… but that would need the library to be compiled with "-g" option. — Michael Laffargue
– Michael Laffargue, Commented Mar 13, 2015 at 7:59
Why cant you declare index as a class variable (make it static) — Clyde D'Cruz
– Clyde D'Cruz, Commented Mar 13, 2015 at 8:03
if contains() was named indexOf() and returned the index, instead of returning a boolean, you could get the index by calling indexOf(), and then use it to set the value at this index to null. — JB Nizet
– JB Nizet, Commented Mar 13, 2015 at 8:03
@ClydeD'Cruz that's probably the worst advice to give. Why would two instances share the same index? — JB Nizet
– JB Nizet, Commented Mar 13, 2015 at 8:05
Oh I may not understood, my comment suppose you can't modify the method code. — Michael Laffargue
– Michael Laffargue, Commented Mar 13, 2015 at 8:07

Jon Skeet · Accepted Answer · 2015-03-13 08:13:21Z

5

No. The whole point of it being local to a method is that it only exists within that method. The options are:

Use an instance field, i.e. make it part of the state of the object. That's unlikely to be appropriate.
Use a static field, i.e. make it part of the static of the type. That's almost certainly inappropriate.
Change the existing method to return the information you want.
Create a new method to return the information you want.
Duplicate the existing code within remove so that you can get the index. That would be sad :(

As an example of the last two, you could write:

public int indexOf(Object input) {       
    int index = 0;    
    while(myAsetIterator.hasNext()) {
        index++;
        if (input.equals(myAsetIterator.next())) {
            return index;
        }
    }
    return -1;
}

public boolean contains(Object input) {
    return indexOf(input) == -1;
}

... then in your remove method, you'd use indexOf instead of contains.

edited Mar 13, 2015 at 8:13

answered Mar 13, 2015 at 8:07

Jon Skeet

1.5m893 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Arkantos Over a year ago

Just a small correction, in case there's a match, you're not returning updated index , always returning -1 :)

Jon Skeet Over a year ago

@Arkantos: Fixed, thanks. (In fact it would have failed to compile :)

Collectives™ on Stack Overflow

Can I use value of a local variable defined in a method, in other method in Java?

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related