How to sort a List in java

How to sort a List in java

In this article, explaining how to sort a list in java. We can sort list which contains Primitive data types or Wrapper Class Types by using Collections.sort(list) or list.stream().forEach(); We can’t sort list which contains object data types so that we have to use a comparator or comparable interface to sort the list.

 

Primitive data List Sorting

Create List without any wrapper type and add homogeneous elements instead of heterogeneous elements

Homogeneous Elements

List list=new ArrayList();list.add(3);list.add(6);

 

Heterogeneous Elements

List list=new ArrayList();
list.add(3);
list.add("Hello");

 

Homogeneous Elements Example

ListPrimitiveDataSorting.java

package com.narayanatutorial.primitive.sorting;

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

public class ListPrimitiveDataSorting {

	public static void main(String args[]) {
		List list = new ArrayList();
		list.add(123);
		list.add(34);
		list.add(567);
		System.out.println("****Before Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		Collections.sort(list);

		System.out.println("****After Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		list.clear();

		list = new ArrayList();
		list.add(123);
		list.add(34);
		list.add(567);

		// sorting using stream
		System.out.println("**** Sorting using list stream ****");
		list.stream().sorted().forEach(value -> System.out.println(value));

	}
}

 

 

Integer Wrapper Classe Type List Sorting

ListIntegerSorting.java

package com.narayanatutorial.primitive.sorting;

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

public class ListIntegerSorting {

	public static void main(String args[]) {
		List<Integer> list = new ArrayList<Integer>();
		list.add(123);
		list.add(34);
		list.add(567);
		System.out.println("****Before Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		Collections.sort(list);

		System.out.println("****After Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		list.clear();

		list = new ArrayList<Integer>();
		list.add(123);
		list.add(34);
		list.add(567);

		// sorting using stream
		System.out.println("**** Sorting using list stream ****");
		list.stream().sorted().forEach(value -> System.out.println(value));

	}
}

Ouput

****Before Sorting****
123
34
567
****After Sorting****
34
123
567
**** Sorting using list stream ****
34
123
567

String Type List Sorting

ListStringSorting.java

package com.narayanatutorial.primitive.sorting;

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

public class ListStringSorting {

	public static void main(String args[]) {
		List<String> list = new ArrayList<String>();
		list.add("Tutorial");
		list.add("Narayana");
		list.add("Swamy");
		System.out.println("****Before Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		Collections.sort(list);

		System.out.println("****After Sorting****");
		list.stream().forEach(name -> System.out.println(name));
		list.clear();

		list = new ArrayList<String>();
		list.add("Tutorial");
		list.add("Narayana");
		list.add("Swamy");
		// sorting using stream
		System.out.println("**** Sorting using list stream ****");
		list.stream().sorted().forEach(value -> System.out.println(value));

	}
}

Output

****Before Sorting****
Tutorial
Narayana
Swamy
****After Sorting****
Narayana
Swamy
Tutorial
**** Sorting using list stream ****
Narayana
Swamy
Tutorial

Long Wrapper Classe Type List Sorting

ListLongSorting.java

package com.narayanatutorial.primitive.sorting;

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

public class ListLongSorting {

	public static void main(String args[]) {
		List<Long> list = new ArrayList<Long>();
		list.add(123L);
		list.add(34L);
		list.add(567L);
		System.out.println("****Before Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		Collections.sort(list);

		System.out.println("****After Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		list.clear();

		list = new ArrayList<Long>();
		list.add(123L);
		list.add(34L);
		list.add(567L);

		// sorting using stream
		System.out.println("**** Sorting using list stream ****");
		list.stream().sorted().forEach(value -> System.out.println(value));

	}
}

Output

****Before Sorting****
123
34
567
****After Sorting****
34
123
567
**** Sorting using list stream ****
34
123
567

Double Wrapper Classe Type List Sorting

ListDoubleSorting.java

package com.narayanatutorial.primitive.sorting;

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

public class ListDoubleSorting {

	public static void main(String args[]) {
		List<Double> list = new ArrayList<Double>();
		list.add(123.5);
		list.add(34.4);
		list.add(567.3);
		System.out.println("****Before Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		Collections.sort(list);

		System.out.println("****After Sorting****");
		list.stream().forEach(name -> System.out.println(name));

		list.clear();

		list = new ArrayList<Double>();
		list.add(123.5);
		list.add(34.4);
		list.add(567.3);

		// sorting using stream
		System.out.println("**** Sorting using list stream ****");
		list.stream().sorted().forEach(value -> System.out.println(value));

	}
}

Output

****Before Sorting****
123.5
34.4
567.3
****After Sorting****
34.4
123.5
567.3
**** Sorting using list stream ****
34.4
123.5
567.3

 

Get full source code from Git.