Hi friend,


Difference Stack vs Heap

Stack

When a function or a method calls another function which in turns calls another function etc.,
the execution of all those functions remains suspended until the very last function returns its value.

This chain of suspended function calls is the stack, because elements in the stack (function calls) depend on each other.

The stack is important to consider in exception handling and thread executions.

Heap
The heap is simply the memory used by programs to store variables.
Element of the heap (variables) have no dependencies with each other and can always be accessed randomly at any time.

Example of Stack :

import java.io.*;
import java.util.*;

public class StackImplement{
Stack<Integer> stack;
String str;
int num, n;
public static void main(String[] args){
StackImplement q = new StackImplement();
}
public StackImplement(){
try{
stack = new Stack<Integer>();
InputStreamReader ir = new InputStreamReader(System.in);
BufferedReader bf = new BufferedReader(ir);
System.out.print("Enter number of elements : ");
str = bf.readLine();
num = Integer.parseInt(str);
for(int i = 1; i <= num; i++){
System.out.print("Enter elements : ");
str = bf.readLine();
n = Integer.parseInt(str);
stack.push(n);
}
}
catch(IOException e){}
System.out.print("Retrieved elements from the stack : ");
while (!stack.empty()){
System.out.print(stack.pop() + " ");
}
}

Example of Heap :

public class heap_Sort{
public static void main(String a[]){
int i;
int arr[] = {1,3,4,5,2};

System.out.println("\n Heap Sort\n---------------\n");
System.out.println("\n Unsorted Array\n\n");
for (i = 0; i < arr.length; i++)
System.out.print(" "+arr[i]);
for(i=arr.length; i>1; i--){
fnSortHeap(arr, i - 1);
}
System.out.println("\n Sorted array\n---------------\n");
for (i = 0; i < arr.length; i++)
System.out.print(" "+arr[i]);
}

public static void fnSortHeap(int array[], int arr_ubound){
int i, o;
int lChild, rChild, mChild, root, temp;
root = (arr_ubound-1)/2;

for(o = root; o >= 0; o--){
for(i=root;i>=0;i--){
lChild = (2*i)+1;
rChild = (2*i)+2;
if((lChild <= arr_ubound) && (rChild <= arr_ubound)){
if(array[rChild] >= array[lChild])
mChild = rChild;
else
mChild = lChild;
}
else{
if(rChild > arr_ubound)
mChild = lChild;
else
mChild = rChild;
}

if(array[i] < array[mChild]){
temp = array[i];
array[i] = array[mChild];
array[mChild] = temp;
}
}
}
temp = array[0];
array[0] = array[arr_ubound];
array[arr_ubound] = temp;
return;
}
}

For more information on Stack or Heap Visit to :

http://www.roseindia.net/java/java-get-example/

http://www.roseindia.net/java/example/java/util/

Thanks
http://www.roseindia.net/java/beginners/