This topic is about Java Generics – 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.
Example
Create the following java program using any editor of your choice.
package com.Adglob;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class GenericsTester {
public static void main(String[] args) {
Map<Integer,Integer> integerMap
= new HashMap<Integer,Integer>();
integerMap.put(1, 10);
integerMap.put(2, 11);
Map<String,String> stringMap = new HashMap<String,String>();
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<Integer> integerIterator = integerMap.keySet().iterator();
while(integerIterator.hasNext()) {
System.out.printf("Integer Value :%d\n", integerIterator.next());
}
// iterate values.
Iterator<String> 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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