用相同的名称在Java中调整数组大小

Question

I'm trying to resize an array to my 'push' method, but in the output the number '6' it's not there.

Any clue?

public void push(int value) {
        if (size != maxSize){ 
            top++;
            stackArray[top] = value;
            size++;
        }else if (size == maxSize){
            stackArray = Arrays.copyOf(stackArray, size * 2);
            maxSize = size * 2;
            size++;
        }else{
            throw new RuntimeException();
        }
    }

Pop method

public int pop() {
        if (size != 0){
            size--;
            return stackArray[top--];
        } else {
            throw new RuntimeException();
        }
    }

I put some elements on that stack

Stack theStack= new Stack(5);

    theStack.push(1);
    theStack.push(2);
    theStack.push(3);
    theStack.push(4);
    theStack.push(5);
    theStack.push(6);
    theStack.push(7);

    System.out.println(theStack.pop());
    System.out.println(theStack.pop());
    System.out.println(theStack.pop());
    System.out.println(theStack.pop());
    System.out.println(theStack.pop());
    System.out.println(theStack.pop());

And then i've got this

7 5 4 3 2 1

Answer 1

In the case size == maxSize , you don't add 6 after resizing the array. Please modify your method to something like this.

Now, you are resizing first (if required). Then do your insertion as normal.

public void push(int value) {
    // resize if required
    if (size == maxSize){
        stackArray = Arrays.copyOf(stackArray, size * 2);
        maxSize = size * 2;
    }

    // then do the addition to the array stuff
    if (size != maxSize){ 
        top++;
        stackArray[top] = value;
        size++;
    } else {
        throw new RuntimeException();
    }
}