package test;
public class MyStack<T> {
//initialize
T[] arr = null;
public MyStack(){
arr = (T[])new Object[0];
}
//PUSH
public void push(T element) {
//create a new array 1 longer than the original one
T[] newArr = (T[])new Object[arr.length + 1];
//copy all element from arr to newArr
for(int i = 0; i < arr.length; i++) {
newArr[i] = arr[i];
}
//put the new element into the newArr
newArr[newArr.length - 1] = element;
//copy newArr to arr
arr = newArr;
}
public T pop() {
//check first
if(arr.length == 0) {
throw new ArrayIndexOutOfBoundsException();
}
//create a newArr 1 shorter than arr
T[] newArr = (T[])new Object[arr.length - 1];
//copy all element from arr to the newArr(except the last one)
for(int i = 0; i < newArr.length; i++) {
newArr[i] = arr[i];
}
//get the last element in arr
T ele = arr[arr.length - 1];
//copy newArr to arr
arr = newArr;
//return the last element
return ele;
}
public T peek() {
//check first
if(arr.length == 0) {
throw new ArrayIndexOutOfBoundsException();
}
//return the last element in the array
return arr[arr.length - 1];
}
public boolean isEmpty() {
return arr.length == 0;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
// Create a stack
MyStack ms = new MyStack();
// PUSH func
ms.push(100);
ms.push(99);
ms.push(98);
ms.push(97);
ms.push("a");
ms.push("b");
ms.push("c");
// POP func
System.out.println(ms.pop());
System.out.println(ms.pop());
System.out.println(ms.pop());
System.out.println(ms.pop());
System.out.println(ms.pop());
System.out.println(ms.pop());
System.out.println("----------------");
// Peek func
System.out.println(ms.peek());
System.out.println("----------------");
// ISEMPTY func
System.out.println(ms.isEmpty());
}
}
