Java 7 Type Inference

Java 7 introduced a new feature Type Interface which provides ability to compiler to infer the type of generic instance. We can replace the type arguments with an empty set of type parameters (<>) diamond.
Before Java 7 following approach was used:

List<integer> list = new List<integer>();

</integer></integer>

List<integer> list = new List<integer>(); </integer></integer>

List list = new List();

We can use following approach with Java 7:

List<integer> list = new List<>();

</integer>

List<integer> list = new List<>(); </integer>

List list = new List<>();

We just used diamond here and type argument is there.

Example

package com.w3schools;

import java.util.ArrayList;

import java.util.List;

public class TestExample {

public static void main(String args[]){

//Prior to Java 7

List<integer> list1 = new ArrayList<integer>();

list1.add(10);

for (Integer element : list1) {

System.out.println(element);

}

//In Java 7, Only diamond is used

List<integer> list2 = new ArrayList<>();

list2.add(10);

for (Integer element : list2) {

System.out.println(element);

}

</integer></integer></integer>

package com.w3schools; import java.util.ArrayList; import java.util.List; public class TestExample { public static void main(String args[]){ //Prior to Java 7 List<integer> list1 = new ArrayList<integer>(); list1.add(10); for (Integer element : list1) { System.out.println(element); } //In Java 7, Only diamond is used List<integer> list2 = new ArrayList<>(); list2.add(10); for (Integer element : list2) { System.out.println(element); } } } </integer></integer></integer>

package com.w3schools;

import java.util.ArrayList;
import java.util.List;

public class TestExample {
	public static void main(String args[]){
		 //Prior to Java 7    
        List list1 = new ArrayList();  
        list1.add(10);  
        for (Integer element : list1) {  
            System.out.println(element);  
        }  
        //In Java 7, Only diamond is used 
        List list2 = new ArrayList<>();   
        list2.add(10);  
        for (Integer element : list2) {  
            System.out.println(element);  
        }  
	}  
}

Output

10 10

10
10