Home Java Java-exception Example to show Hash map exception in java

Example to show Hash map exception in java
Posted on: October 24, 2008 at 12:00 AM

Here we are describing the use of using exception class in java .This tutorial describes the way to handle exception appropriately in your programs and designs.

Example to show Hash map exception in java

The implementation of map interface is based on Hash table.

Interface in Mapping -

1)The Hash Map implements map.

2)The Tree Map implements sorted map.

3)Map-Entry describe the access method to key-value pairs

Understand with Example

Hash map in java is same as the Hash table. The program given below gives the brief description of exception that occurs while executing Hash map.
Hash Map hash Map = new Hash Map():-This is the way for creating a HashMap.Here we have created an empty Hash Map.
hashMap.put("ABS", new Double(3434.34)):-This is the method of the Hash Map for adding the specified value with the specified key in this map.
hashMap.entrySet():-This method returns a collection view of the mappings contained in this map.

me.getKey( ):- This method return you the key-value pair stored in a Map.

On execution of the code, the code show you an exception indicating an string cannot be converted into double.

Hashmapexception.java




import java.util.*;

import java.util.Iterator;



public class Hashmapexception {



  public static void main(String[] args) {



  HashMap hashMap = new HashMap();

  hashMap.put("ABS", new Double(3434.34));

  hashMap.put("ABD", new Double(123.22));

  hashMap.put("cccc", "jdshgjhs");

  Set set = hashMap.entrySet();



  Iterator i = set.iterator();

  while (i.hasNext()) {

  Map.Entry me = (Map.Entry) i.next();

  System.out.println(me.getKey() + " : " + me.getValue());

  }

  double balance = ((Double) hashMap.get("cccc")).doubleValue();

  hashMap.put("cccc", new Double(balance + 1000));

  System.out.println("balance : " + hashMap.get("cccc"));



  }

}

Output of the program

Exception in thread "main" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
at Hashmapexception.main(Hashmapexception.java:20)
Java Result: 1

Download source code

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