Java Program to implement stack using array

A stack is a data structure which is a  logical representation of  a real physical stack or pile of objects, where insertion and deletion of items takes place at one end called top of the stack. The basic concept can be illustrated by thinking of the data set as a stack of plates or books where you can only take the top item off the stack in order to remove things from it. In a stack last added item is deleted first and so it is called a LIFO (Last In First Out) data structure.

Following is the implementation of a stack in Java programming language by using array. This example has two files MyStack.java and JavaStack.java.
MyStack is a class that contains the function to perform stack operations. Member functions of MyStack are:

1.  public boolean push (int value)  -  To add a new value to the stack. On success, it returns true else it returns false.
2.  public int  pop ()  - To take off or pop a value from the stack. On success it returs the poped value else it returns -1
3.  public int  top () - To access the value at the top of the stack. On success it returns the value at stack top else it returns -1
4.  public boolean  isFull ()  - To check whether the stack is full or not.
5.  public boolean  isEmpty() - To check whether the stack is empty or not
6.  public void display()  - to display the content of the stack


JavaStack class contains the main function of the program. It uses an instance of MyStack and tests the functions.

Source Code

MyStack.java

public class MyStack {
    private int [] data;
    private int size;
    private int top;
  
  
    /* Default Constructer  */
    public MyStack () {
        this.size=5; // Default size
        this.data = new int [this.size];
        top = -1;
    }
  
    /* Overloaded Constructer */
    public MyStack (int size) {
        this.size=size;
        data = new int [this.size];
        top = -1;
    }
  
    /* Function to push a value.*/
    public boolean push (int value) {
        if (this.isFull()) {
            return false;
        }
      
        this.top++;
        this.data[this.top]=value;
      
        return true;                      
    }
  
     /* Function to pop a value*/
    public int  pop () {
        int value;
      
        if (this.isEmpty()) {
            return -1;
        }
              
        value = this.data[this.top];
        this.top--;
      
        return value;                      
    }
  
    /* Function to get the top value*/
    public int  top () {
        int value;
      
        if (this.top == -1) {
            return -1;
        }
      
      
        value = this.data[this.top];
            
        return value;                      
    }
  
    /* Function to check whether stack is full*/
    public boolean  isFull () {              
        if (this.top >= this.size-1) {
            return true;
        }              
        return false;                      
    }
  
    /* Function to check whether stack is empty */
    public boolean  isEmpty () {              
        if (this.top == -1) {
            return true;
        }                  
        return false;                      
    }
  
    /* Function to display stack content */
     public void  display () {              
        if (this.isEmpty()) {
            System.out.println("Stack is empty!");
            return;
        }
              
        for (int i=this.top;i>=0;i--){
            System.out.println(this.data[i]);
        }   
        return;                      
    }      
}
}

JavaStack.java

public class JavaStack {
    public static void main(String[] args) {
        MyStack ms = new MyStack();
       
        System.out.println("Pushed 1:" + ms.push(1));
        System.out.println("Pushed 2:" + ms.push(2));
        System.out.println("Pushed 3:" + ms.push(3));
        System.out.println("Pushed 4:" + ms.push(4));
        System.out.println("Pushed 5:" + ms.push(5));
        System.out.println("Pushed 6:" + ms.push(6));
        System.out.println("Is Full:" + ms.isFull());       
       
        System.out.println("Stack Content");
        ms.display();       
       
        System.out.println("Poped:" + ms.pop());
        System.out.println("Poped:" + ms.pop());
        System.out.println("Poped:" + ms.pop());
        System.out.println("Poped:" + ms.pop());
        System.out.println("Poped:" + ms.pop());
        System.out.println("Poped:" + ms.pop());
       
        ms.display();                     
    }
}

Output

Pushed 1:true
Pushed 2:true
Pushed 3:true
Pushed 4:true
Pushed 5:true
Pushed 6:false

Is Full:true

Stack Content
5
4
3
2
1

Poped:5
Poped:4
Poped:3
Poped:2
Poped:1
Poped:-1

Stack is empty!

How to test the program on your computer? 

1. Create MyStack.java file and copy the source code in the section 1.
2. Create JavaStack.java and copy the source code in the section 2.
3. Compile the program by using the command javac JavaStack.java
4. Run the program by using the command java JavaStack