In this Data structures tutorial we will learn how to push and pop Employee object in a stack in java with example and program. We will use generic implementation of stack to achieve it in java.
Full Program/Example to Push and pop Employee object in Stack implementation in java >
class Employee {
private String id;
private String name;
/**
* Employee constructor
*/
public Employee(String id, String name) { // constructor
this.id = id;
this.name = name;
}
@Override
public String toString() {
return "Employee [id=" + id + ", name=" + name + "] ";
}
}
/**
*Exception to indicate that Stack is full.
*/
class StackFullException extends RuntimeException {
public StackFullException(){
super();
}
public StackFullException(String message){
super(message);
}
}
/**
*Exception to indicate that Stack is empty.
*/
class StackEmptyException extends RuntimeException {
public StackEmptyException(){
super();
}
public StackEmptyException(String message){
super(message);
}
}
/**
* Stack class(generic type)
*/
class Stack<T> {
private int size;
private T[] stackAr;
private int top; // top of stack
/**
* Constructor for initializing Array.
*/
@SuppressWarnings("unchecked")
public Stack(int size) {
this.size = size;
stackAr = (T[])new Object[size]; //Creation of Generic Stack Array
top = -1; // initialize Stack to with -1
}
/**
* Push items in stack, it will put items on top of Stack.
*/
public void push(T value){
if(isFull()){
throw new StackFullException("Cannot push "+value+", Stack is full");
}
stackAr[++top] = value;
}
/**
* Pop items in stack, it will remove items from top of Stack.
*/
public T pop() {
if(isEmpty()){
throw new StackEmptyException("Stack is empty");
}
return stackAr[top--]; // remove item and decrement top as well.
}
/**
* @return true if Stack is empty
*/
public boolean isEmpty(){
return (top == -1);
}
/**
* @return true if stack is full
*/
public boolean isFull(){
return (top == size - 1);
}
}
/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */
/**
* StackExampleGeneric Main class
*/
public class StackExampleGeneric {
public static void main(String[] args) {
Stack<Employee> stack = new Stack<Employee>(10); // Creation of Generic Stack
stack.push(new Employee("11", "sam"));
stack.push(new Employee("22", "sam"));
stack.push(new Employee("33", "sam"));
stack.push(new Employee("44", "sam"));
stack.push(new Employee("11", "sam"));
System.out.print("Popped items: ");
System.out.print(stack.pop()+" ");
System.out.print(stack.pop()+" ");
System.out.print(stack.pop()+" ");
System.out.print(stack.pop()+" ");
System.out.print(stack.pop()+" ");
}
}
/** OUTPUT
Popped items: Employee [id=11, name=sam] Employee [id=44, name=sam] Employee [id=33, name=sam] Employee [id=22, name=sam] Employee [id=11, name=sam]
*/
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Complexity of push and pop Employee object in a stack in java>
Complexity of insertion and deletion at first is O(1) in java.
As we have to always insert at first - best case, average case and worst case are same in java.
So in this Data structures tutorial we learned how to push and pop Employee object in a stack in java with example and program. We used generic implementation of stack to achieve it in java.
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1) Stacks, Queues in Data Structures in java
2) Single LinkedList implementations in Data Structures in java:-
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