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Thread: HashMap : Simple Usage and Understanding

  1. #1

    Post HashMap : Simple Usage and Understanding

    Map is an object that stores key/volume pairs. Given a key, you can find its value. Keys must be unique, but values may be duplicated.

    The HashMap class uses a hash table to implementation of the map interface. This allows the execution time of basic operations, such as get() and put() to be constant.

    An example is below:

    Q. Find the numbers Divisible by an array of numbers ie div[] between a range ie from 1 to N?
    Ans. This can be solved using many ways, but we will be solving using HashMap which will help u understand the concept of HashMap in a better way..

    For this u can use your command prompt, eclipse, netbeans or any IDE that supports JAVA. Using eclipse is much easier.

    CODE :
    1:  import java.util.HashMap; 
    2:  public class Main { 
    3:    public static int usingHashmap(int N,int div[]){ 
    4:      int count=0; 
    5:      HashMap<Integer, Integer> key=new HashMap<Integer, Integer>(); 
    6:      for(int i=1;i<N;i++){ 
    7:        key.put(i, i); 
    8:      } 
    9:      for(int i=0;i<div.length;i++){ 
    10:        for(int k=1;k<N;k++){ 
    11:        if(key.get(k)==null){ 
    12:          key.put(k, -1); 
    13:        } 
    14:          if(key.get(k)%div[i]==0){ 
    15:            count++; 
    16:            key.remove(k); 
    17:          } 
    18:        } 
    19:      } 
    20:      System.out.println(count); 
    21:      return count; 
    22:    } 
    23:    public static void main(String[] args) { 
    24:      new Main().usingHashmap(50, new int[]{3,2}); 
    25:    } 
    26:  }
    Last edited by weakprogrammer; June 25th, 2011 at 03:48 PM.
    Warm Regards,


    Code 2 Learn

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: HashMap : Simple Usage and Understanding

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