StackArray.java

public class StackArray{
    private String[] s;
    private int count;
    
    public StackArray(int size){
       if(size > 0)
          s = new String[size];
       else
          s = new String[10];
       
       
       count = 0;
    }
    
    public StackArray(){
       this(10);
    }
    
    private boolean isEmpty(){
       return count == 0;
    }
    
    public boolean isFull(){
       return count == s.length;
    }
    
    public boolean push(String val){
       if(!isFull()){
          s[count++] = val;
          return true;
       }
       return false;
    }
    
    public boolean pop(){
       if(!isEmpty()){
          s[count - 1] = null;
          count--;
          return true;
       }
       return false;
    }
    
    public String peek(){
       return isEmpty()? null : s[count-1];
    }
    
    public void display(){
       if(!isEmpty()){
          for(int i = count - 1; i >= 0; i--){
             System.out.println("[" + s[i] + "]");
          }
       }
       else
          System.out.println("Stack is empty");
    }
 
 }