JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Java Dynamic Stack Implementation


In this example, the stack will never comes to stack overflow case, beacuse its capacity will keep increases as it reaches to max capacity, so it is very dynamic in capacity.


package com.java2novice.ds.stack;

public class MyDynamicStack {

	private int stackSize;
	private int[] stackArr;
	private int top;

	/**
	 * constructor to create stack with size
	 * @param size
	 */
	public MyDynamicStack(int size) {
		this.stackSize = size;
		this.stackArr = new int[stackSize];
		this.top = -1;
	}

	/**
	 * This method adds new entry to the top 
	 * of the stack
	 * @param entry
	 * @throws Exception 
	 */
	public void push(int entry){
		if(this.isStackFull()){
			System.out.println(("Stack is full. Increasing the capacity."));
			this.increaseStackCapacity();
		}
		System.out.println("Adding: "+entry);
		this.stackArr[++top] = entry;
	}

	/**
	 * This method removes an entry from the 
	 * top of the stack.
	 * @return
	 * @throws Exception 
	 */
	public int pop() throws Exception {
		if(this.isStackEmpty()){
			throw new Exception("Stack is empty. Can not remove element.");
		}
		int entry = this.stackArr[top--];
		System.out.println("Removed entry: "+entry);
		return entry;
	}
	
	/**
	 * This method returns top of the stack
	 * without removing it.
	 * @return
	 */
	public long peek() {
		return stackArr[top];
	}

	private void increaseStackCapacity(){
		
		int[] newStack = new int[this.stackSize*2];
		for(int i=0;i<stackSize;i++){
			newStack[i] = this.stackArr[i];
		}
		this.stackArr = newStack;
		this.stackSize = this.stackSize*2;
	}
	
	/**
	 * This method returns true if the stack is 
	 * empty
	 * @return
	 */
	public boolean isStackEmpty() {
		return (top == -1);
	}

	/**
	 * This method returns true if the stack is full
	 * @return
	 */
	public boolean isStackFull() {
		return (top == stackSize - 1);
	}

	public static void main(String[] args) {
		MyDynamicStack stack = new MyDynamicStack(2);
		for(int i=1;i<10;i++){
			stack.push(i);
		}
		for(int i=1;i<4;i++){
			try {
				stack.pop();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

Output:
Adding: 1
Adding: 2
Stack is full. Increasing the capacity.
Adding: 3
Adding: 4
Stack is full. Increasing the capacity.
Adding: 5
Adding: 6
Adding: 7
Adding: 8
Stack is full. Increasing the capacity.
Adding: 9
Removed entry: 9
Removed entry: 8
Removed entry: 7
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List of Stack Data Structure Examples

  1. Stack introduction & implementation
  2. Java Dynamic Stack Implementation
  3. Stack implementation using generics bounded type.
  4. Reverse a word or string using Stack data structure.
  5. Write a program to find out delimiter matching using stack.
  6. Convert a decimal into a binary number using stack.
  7. Towers of Hanoi implementation using stack.
  8. Evaluation of an infix expression that is fully parenthesized using stack in java.
Knowledge Centre
What is fail-fast in java?
A fail-fast system is nothing but immediately report any failure that is likely to lead to failure. When a problem occurs, a fail-fast system fails immediately. In Java, we can find this behavior with iterators. Incase, you have called iterator on a collection object, and another thread tries to modify the collection object, then concurrent modification exception will be thrown. This is called fail-fast.
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Insanity: doing the same thing over and over again and expecting different results.
-- Albert Einstein

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java is registered trademark of Oracle.
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