Java8 Programming Examples

Test if a List is an Unmodifable List in Java

java8

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
public class Demo {
	public static void main(String[] args) {
		List<Integer>list = new LinkedList<Integer>();
		list.add(10);
		list.add(20);
		list.add(30);
		list.add(40);
		list.add(50);
		List<Integer>unmodifiable = Collections.unmodifiableList(list);
		if (unmodifiable.getClass().getName().contains("UnmodifiableList"))
			System.out.println("This is an UnmodifiableList" );
		else
			System.out.println("This is not an UnmodifiableList" );
	}
}

Shuffle a List in Java

java8

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class Demo {
public static void main(String args[]) {
    Integer[] strArray = new Integer[] { 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 };
    List<Integer>list = Arrays.asList(strArray);
    System.out.println("List = "+list);
    Collections.shuffle(list);
    System.out.println("Shuffled List = "+list);
  }
}

Java Program to create Duration from seconds

java8

import java.time.Duration;
public class Demo {
	public static void main(String[] args) {
		Duration duration = Duration.ofDays(10);
		Duration duration1 = Duration.ofHours(10);
		Duration duration2 = Duration.ofMillis(10);
		Duration duration3 = Duration.ofMinutes(10);
		System.out.println("Seconds in 10 days = "+duration.getSeconds());
		System.out.println("Seconds in 10 hours = "+duration1.getSeconds());
		System.out.println("Seconds in 10 milliseconds = "+duration2.getSeconds());
		System.out.println("Seconds in 10 minutes = "+duration3.getSeconds());
	}
}

Retain elements from a Collection in another Collection in Java

java8

import java.util.ArrayList;
import java.util.List;
public class Demo {
	public static void main(String args[]) throws Exception {
		List<Integer>list = new ArrayList<Integer>();
		list.add(100);
		list.add(200);
		list.add(200);
		list.add(200);
		list.add(300);
		list.add(400);
		list.add(400);
		list.add(500);
		List <Integer>list2 = new ArrayList<Integer>();
		list2.add(100);
		list2.add(200);
		list2.add(300);
		list2.add(400);
		list.retainAll(list2);
		System.out.println("Resultant list = "+list);
	}
}

Remove all elements from a Collection in another Collection in Java

java8

import java.util.ArrayList;
import java.util.List;
public class Demo {
	public static void main(String args[]) throws Exception {
		List<Integer>list = new ArrayList<Integer>();
		list.add(100);
		list.add(200);
		list.add(200);
		list.add(200);
		list.add(300);
		list.add(400);
		list.add(400);
		list.add(500);
		List <Integer>list2 = new ArrayList<Integer>();
		list2.add(100);
		list2.add(200);
		list2.add(300);
		list2.add(400);
		list.removeAll(list2);
		System.out.println("Resultant list = "+list);
	}
}

Java Program to insert all elements of other Collection

java8

import java.util.ArrayList;
import java.util.Vector;
public class Demo {
	public static void main(String[] args) {
		ArrayList<String>arr = new ArrayList<String>();
		arr.add("50");
		arr.add("100");
		arr.add("150");
		arr.add("200");
		arr.add("250");
		arr.add("300");
		Vector<String>vector = new Vector<String>();
		vector.add("500");
		vector.add("700");
		vector.add("800");
		vector.add("1000");
		// gets added at index 3
		arr.addAll(3, vector);
		System.out.println("Result after append...");
		for (String str: arr)
		 System.out.println(str);
	}
}

Java Program to get previous and next index using ListIterator

java8

import java.util.ArrayList;
import java.util.ListIterator;
public class Demo {
	public static void main(String[] args) {
		ArrayList<Integer>arrList = new ArrayList<Integer>();
		arrList.add(100);
		arrList.add(200);
		arrList.add(300);
		arrList.add(400);
		arrList.add(500);
		arrList.add(600);
		arrList.add(700);
		arrList.add(800);
		arrList.add(900);
		arrList.add(1000);
		System.out.println("ArrayList...");
		for (Integer i: arrList)
			System.out.println(i);
			ListIterator<Integer>iterator = arrList.listIterator();
			System.out.println("Previous Index =" + iterator.previousIndex());
			System.out.println("Next Index = " + iterator.nextIndex());
			iterator.next();
			System.out.println("Previous Index = " + iterator.previousIndex());
			System.out.println("Next Index =" + iterator.nextIndex());
			iterator.next();
			iterator.next();
			System.out.println("Previous Index = " + iterator.previousIndex());
			System.out.println("Next Index = " + iterator.nextIndex());
	}
}

Java Program to display sub-list of ArrayList

java8

import java.util.ArrayList;
import java.util.List;
public class Demo {
	public static void main(String[] args) {
		ArrayList<String>arrayList = new ArrayList<String>();
		arrayList.add("100");
		arrayList.add("200");
		arrayList.add("300");
		arrayList.add("400");
		arrayList.add("500");
		arrayList.add("600");
		arrayList.add("700");
		arrayList.add("800");
		arrayList.add("900");
		arrayList.add("1000");
		System.out.println("ArrayList...");
		for (String s: arrayList)
			System.out.println(s);
			List<String>list = arrayList.subList(4, 8);
			System.out.println("SubList of ArrayList...");
			for (int i = 0; i<list.size(); i++)
				System.out.println(list.get(i));
	}
}

Program to get the number of hours in this duration

java8

import java.time.Duration;
public class Demo {
	public static void main(String[] args) {
		Duration duration =  Duration.ofDays(25);
		System.out.println("Hours in 25 days = "+duration.toHours());
	}
}

Fetch elements with iterator in Java

java8

import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
public class Demo {
	public static void main(String[] a) {
		List<String>list = Arrays.asList(new String[] { "P", "Q", "R", "S", "T", "U", "V", "W" });
		Iterator<String>i = list.iterator();
		System.out.println("Displaying elements...");
		while (i.hasNext()) {
			System.out.println(i.next());
		}
	}
}

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