1. push(), pop(), isEmpty(), top(), size()
2. Add customized exception: EmptyStack for pop() and top()
3. Add Exception message
4. throws EmptyStack exception
5. try and catch the EmptyStack exception

/*
/Users/cat/myfile/bitbucket/java/try_stack.java

1. Implement stack with array
   functionarity: push(), pop(), isEmpty(), size()
   reallocate memory when the array is full
   copy the all current elements to a new array
2. Add customized Exception
   if the stack is empty, then throw exception when pop() and top() are called

customized or unchecked exception

class MyException extends Exception{..}

void fun() throws MyException{
    throw new MyException();
}    

    try{
    }catch(MyException e){
        System.out.println(e.getMessage);
    }
    or rethrow the MyException
    try{
    }catch(MyException e){
        throw e;
    }

*/

class EmptyStack extends Exception{
    String msg;
    public EmptyStack(String msg){
        super(msg);
        this.msg = msg;
    }
}

class MyStack{
    int[] arr;
    int count = 0;
    int num = 2;
    public MyStack(){
        arr = new int[num]; 
    }
    public void push(int n){
        if(arr != null){
            if(count < num){
                arr[count] = n;
                count++;
            }else{
                int[] tmp = new int[num];
                for(int i=0; i 0){
            int inx = count - 1;
            count--;
            return arr[inx];
        }
        else
            throw new EmptyStack("Stack is empty.");
    }
    public int top() throws EmptyStack {
        if(!isEmpty())
            return arr[count - 1];
        else 
            throw new EmptyStack("Stack is empty.");
    }
    public Boolean isEmpty(){
        return count == 0;
    }
    public int size(){
        return count;
    }
    public void print(){
        for(int i=0; i < size(); i++){
            Print.p(arr[i]);
        } 
    }
}