Java Generics - List

Java has provided generic support in List interface.

Syntax

List<T> list = new ArrayList<T>();

Where

• list − object of List interface.

• T − The generic type parameter passed during list declaration.

Description

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

Example

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

package com.howcodex;

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

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

      List<Integer> integerList = new ArrayList<Integer>();
  
      integerList.add(Integer.valueOf(10));
      integerList.add(Integer.valueOf(11));

      List<String> stringList = new ArrayList<String>();
  
      stringList.add("Hello World");
      stringList.add("Hi World");
 

      System.out.printf("Integer Value :%d\n", integerList.get(0));
      System.out.printf("String Value :%s\n", stringList.get(0));

      for(Integer data: integerList) {
         System.out.printf("Integer Value :%d\n", data);
      }

      Iterator<String> stringIterator = stringList.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 :10
Integer Value :11
String Value :Hello World
String Value :Hi World