IntStack.java

public class IntStack {
    private int [] stack;
    private int top;
    private int size;
    public IntStack(){
        top = -1;
        size = 50;
        stack  = new int[50];
    }
    public IntStack(int size){
        top = -1;
        this.size = size;
        stack  = new int[this.size];
    }
    public boolean push(int value){
        if(!isFull()){
            top++;
            stack[top]=value;
            return true;
        }
        else{
            return false;
        }
    }
    public int pop(){
        return stack[top--];
    }

    public boolean isEmpty(){
        return (top == -1);
    }

    public boolean isFull(){
        return(top==stack.length - 1);
    }
}