Type Interface feature was introduced in Java 7 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>
Listlist = new List ();
We can use following approach with Java 7:
List<integer> list = new List<>();
</integer>
List<integer> list = new List<>();
</integer>
Listlist = new List<>();
We just used diamond here and type argument is there.
Java 8 Type interface improvement:
displayList(new ArrayList<>());
displayList(new ArrayList<>());
displayList(new ArrayList<>());
In java 8 we can call specialized method without explicitly mentioning of type of arguments.
Example
package com.w3schools;
import java.util.ArrayList;
import java.util.List;
public class TestExample {
public static void displayList(List<integer>list){
if(!list.isEmpty()){
list.forEach(System.out::println);
}else{
System.out.println("Empty list");
}
}
public static void main(String args[]){
//Prior to Java 7
List<integer> list1 = new ArrayList<integer>();
list1.add(41);
displayList(list1);
// Java 7, We can left it blank, compiler can infer type
List<integer> list2 = new ArrayList<>();
list2.add(32);
displayList(list2);
//In Java 8, Compiler infers type of ArrayList
displayList(new ArrayList<>());
}
}
</integer></integer></integer></integer>
package com.w3schools;
import java.util.ArrayList;
import java.util.List;
public class TestExample {
public static void displayList(List<integer>list){
if(!list.isEmpty()){
list.forEach(System.out::println);
}else{
System.out.println("Empty list");
}
}
public static void main(String args[]){
//Prior to Java 7
List<integer> list1 = new ArrayList<integer>();
list1.add(41);
displayList(list1);
// Java 7, We can left it blank, compiler can infer type
List<integer> list2 = new ArrayList<>();
list2.add(32);
displayList(list2);
//In Java 8, Compiler infers type of ArrayList
displayList(new ArrayList<>());
}
}
</integer></integer></integer></integer>
package com.w3schools; import java.util.ArrayList; import java.util.List; public class TestExample { public static void displayList(Listlist){ if(!list.isEmpty()){ list.forEach(System.out::println); }else{ System.out.println("Empty list"); } } public static void main(String args[]){ //Prior to Java 7 List list1 = new ArrayList (); list1.add(41); displayList(list1); // Java 7, We can left it blank, compiler can infer type List list2 = new ArrayList<>(); list2.add(32); displayList(list2); //In Java 8, Compiler infers type of ArrayList displayList(new ArrayList<>()); } }
Example
41
32
Empty list
41
32
Empty list
41 32 Empty list