Here is an simplified implementation based on array.
Code:
import java.util.Stack;
public class test {
public static void main(String...args) {
Stack<Integer> stack = new Stack<>();
stack.push(3);
stack.push(6);
stack.push(10);
while(!stack.isEmpty()) {
System.out.println(stack.pop());
}
}
}
Here is a class that achieve stack functionality:
import java.util.Iterator;
public class MyArrayStack <Item> implements Iterable<Item>{
private int N = 0;
private Item[] a = (Item[])new Object[1];
public boolean isEmpty() { return N == 0;}
public int size() {return N;}
private Item[] resize(int maxN) {
Item[] tmp = (Item[])new Object[maxN];
for(int i = 0; i < N; i++) {
tmp[i] = a[i];
}
a = tmp;
return a;
}
public void push(Item item) {
if(N == a.length) {
a = resize(a.length*2);
}
a[N++] = item;
}
public Item pop() {
if(isEmpty()) return null;
Item result = a[--N];
a[N] = null;
if(N > 0 && N == a.length/4) {
a = resize(a.length/2);
}
return result;
}
@Override
public Iterator<Item> iterator() {
return new MyIterator();
}
private class MyIterator implements Iterator<Item> {
private int i = N;
@Override
public boolean hasNext() {
return i > 0;
}
@Override
public Item next() {
return a[--i];
}
}
public static void main(String[] args) {
MyArrayStack<Integer> stack = new MyArrayStack<>();
stack.push(5);
stack.push(10);
stack.push(1);
Iterator<Integer> it = stack.iterator();
System.out.println();
while(it.hasNext()) {
System.out.print(it.next() + " ");
}
System.out.println();
System.out.println(stack.size());
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.isEmpty());
stack.push(7);
stack.push(3);
System.out.println(stack.size());
}
}
Examples:
