Map

Java has provided generic support in Map interface.

Syntax

Set<T> set = new HashSet<T>();

Where

  • set − object of Set Interface.
  • T − The generic type parameter passed during set declaration.

Description

The T is a type parameter passed to the generic interface Set and its implemenation class HashSet.

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Example

Create the following java program using any editor of your choice.

package com.tutorialspoint;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class GenericsTester {
   public static void main(String[] args) {

  Map&lt;Integer,Integer&gt; integerMap 
     = new HashMap&lt;Integer,Integer&gt;();
  integerMap.put(1, 10);
  integerMap.put(2, 11);
  Map&lt;String,String&gt; stringMap = new HashMap&lt;String,String&gt;();

  stringMap.put("1", "Hello World");
  stringMap.put("2","Hi World");
  System.out.printf("Integer Value :%d\n", integerMap.get(1));
  System.out.printf("String Value :%s\n", stringMap.get("1"));
  // iterate keys.
  Iterator&lt;Integer&gt; integerIterator   = integerMap.keySet().iterator();
  while(integerIterator.hasNext()) {
     System.out.printf("Integer Value :%d\n", integerIterator.next());
  }
  // iterate values.
  Iterator&lt;String&gt; stringIterator   = stringMap.values().iterator();
  while(stringIterator.hasNext()) {
     System.out.printf("String Value :%s\n", stringIterator.next());
  }
} }

This will produce the following result −

Output

Integer Value :10
String Value :Hello World
Integer Value :1
Integer Value :2
String Value :Hello World
String Value :Hi World

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