Question

write a java program implementing stacks using arrays. (not with linked list)

Answer 1

Code in java Compiler:-

//a class to implement the stack using array
public class stackimplementation{
int size;
int arr[];
int top;
//the logic here , by using an array, there is no need to remove the element//the element directly from the array, simply we can increase or //decrease the pointer,pointing the indexes of the array.
//If we want to delete the memory of the elements in the array, we can do that too by freeing up the memory space ...
//Array is a simple storage space with some predefined capacity or size
//constructor for stackimplementation to intialize the stack
stackimplementation(int size)
{
this.size = size;
this.arr = new int[size];
this.top = -1;
}
//a method to check the stack is empty or not
public boolean isEmpty()
{
if(top==-1) return true;
return false;
}
// a method to check the stack is full or not
public boolean isFull()
{
if(top==(size-1)) return true;
return false;
}
//a method to push the new element into the stack
public void push(int elementtopush)
{
if(top<size) {
top++;
arr[top] = elementtopush;
System.out.println("The Pushed element is:" + elementtopush);
}else if(top>=(size-1))
{
System.out.println("Stack is Full!");
}
//the other way to use the full method to push a element into the stack
/*if(!isFull())
{ arr[++top] = elementtopush;
System.out.println("Pushed element is: "+elementtopush);
}
else{
  
System.out.println("Stack is Full, pop the elements to push new elements")
}*/
}
//a method to pop the element of the stack
// If we change the function to int then return statements to return the popped element is used................
public void pop()
{
if(top<0) {
System.out.println("There are no elements in the stack,that means stack is empty, push the elements........");
}
else
{
top--;
int x = arr[top];
System.out.println("The popped element is: "+x);
}
//the other way to use the empty method to pop a element from the stack
/*if(!isEmpty())
{ int x = arr[top--];
System.out.println("Popped element is: "+x);
}
else{
  
System.out.println("Stack is empty, there are no elements. Push the elements into the stack ");
}*/
}
//to know the top of the element
// here also the method can be changed to
public void peek()
{
System.out.println("The element at the top of the stack is : "+arr[top]);

}
// the main method in the java program which is called by the java compiler
public static void main(String[] args)
{
//an object of the class stackimplementation is created to use the methods defined in the class such as pop,push etc.......
stackimplementation stack = new stackimplementation(15);
//Initially,there are no elements in the stack
// if(stack.isEmpty()) System.out.println("Stack is empty");
stack.pop();
//pushing the elements
stack.push(10);
stack.push(20);
stack.push(30);
//to know the top of the element means, to which index the pointer top is pointed too...........
stack.peek();
//decreasing the pointer top
stack.pop();
//to know the top of the element means, to which index the pointer top is pointed too...........
stack.peek();

//add some more methods if u want
}//end of the main method
}//end class stackimplementation

Output:-

If you want modifications in the code , for further explanation, please feel free to comment