Tag: streams

collections java

iterate stream with index in Java8

Post author By Rajesh Kumar
Post date February 25, 2020
No Comments on iterate stream with index in Java8

In this post, we will learn to iterate stream with index in Java8

We will come across multiple streams tutorials, but in all the tutorials we never iterate with index numbers

In order to find the current index or other numeric operations index number will help us to get the position

In this tutorial, we are going to use IntStream to get index of the arraylist

Because there is no straight way to get index number in streams

Syntax

IntStream.range(start, end)

Example


import java.util.ArrayList;
import java.util.List;
import java.util.stream.IntStream;

public class IterateStreamWithIndex {

	public static void main(String[] args) {
		try {
			List<String> list = new ArrayList<String>();
			list.add("India");
			list.add("USA");
			list.add("Germany");

			IntStream.range(0, list.size())
					.forEach(x -> System.out.println("The index is " + x + " Value is " + list.get(x)));

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

Output

The index is 0 Value is India
The index is 1 Value is USA
The index is 2 Value is Germany

Github

https://github.com/rkumar9090/BeginnersBug/blob/master/BegineersBug/src/com/geeks/example/IterateStreamWithIndex.java

foreach in java8 using streams

sorting operations in java using streams

Tags iterate, java8, streams

collections java

foreach in java8 using streams

Post author By Rajesh Kumar
Post date February 22, 2020
No Comments on foreach in java8 using streams

In this tutorial, we will learn about foreach in java8 using streams

In java8, We can easily iterate a list using streams.

Streams API provided a lot of features. In this post, we are going to see about foreach

Syntax

stream().forEach({operations});

Example


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

public class ForEachExample {

	public static void main(String[] args) {
		try {

			List studentList = new ArrayList();
			Student student = null;

			student = new Student();
			student.setId(1);
			student.setName("Rajesh");
			student.setAddress("Mumbai");
			studentList.add(student);

			student = new Student();
			student.setId(1);
			student.setName("Kumar");
			student.setAddress("Chennai");
			studentList.add(student);

			studentList.stream()
					.forEach(x -> System.out.println("Name is " + x.getName() + " Address is " + x.getAddress()));

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

Student.java


public class Student {

	private int id;
	private String name;
	private String address;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

}

Output

Name is Rajesh Address is Mumbai
Name is Kumar Address is Chennai

sorting operations in java using streams

Iterate list using streams in java

Github

https://github.com/rkumar9090/BeginnersBug/blob/master/BegineersBug/src/com/geeks/example/ForEachExampleUsingStreams.java

Tags arraylist, foreach, java, java8, streams

collections java

sorting operations in java using streams

Post author By Rajesh Kumar
Post date February 12, 2020
No Comments on sorting operations in java using streams

In this example, we learn sorting operations in java using streams

In Java 8 it is easy to sort records from an arraylist

Streams API providing powerful features to sort the records from a list without modifying it

This will returns a stream consisting of the sorted elements

Syntax

Stream sorted()

list.stream().sorted({operations});

Ascending Example

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

public class AscendingSortingStreams {
    public static void main(String[] args) {
        List list = new ArrayList();
        list.add("Ball");
        list.add("Apple");
        list.add("Cat"); // printitng values before sorting
        System.out.println("Values before sorting ");
        list.stream().forEach(x -> System.out.println(x));
        System.out.println("*** Values After sorting ***");
        list.stream().sorted().forEach(x -> System.out.println(x));
    }
}

Output

Values before sorting 
Ball
Apple
Cat
*** Values After  sorting ***
Apple
Ball
Cat

Descending Example

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

public class DescendingSortingStreams {
    public static void main(String[] args) {
        List list = new ArrayList();
        list.add("Ball");
        list.add("Apple");
        list.add("Cat");
        // printitng values before sorting
        System.out.println("Values before sorting ");
        list.stream().forEach(x -> System.out.println(x));
        System.out.println("*** Values After sorting ***");
        // Comparator.reverseOrder() will sort the records in descending order
        list.stream().sorted(Comparator.reverseOrder()).forEach(x -> System.out.println(x));
    }
}

Output

Values before sorting 
Ball
Apple
Cat
*** Values After  sorting ***
Cat
Ball
Apple

References

Oracle Docs

filter operations in streams on java

Iterate list using streams in java

Tags collections, java, sorting, streams

collections java

filter operations in streams on java

Post author By Rajesh Kumar
Post date February 11, 2020
No Comments on filter operations in streams on java

In this example we learn filter operations in streams on java

In Java 8 it is easy to filter record from an arraylist

Streams API providing powerful features to filter an record from a list without modifying it

This will returns a stream consisting of the elements of this stream that match the given predicate.

Syntax

Stream filter(Predicate<? super T> predicate)<br><br>

list.stream().filter({operations});

Example

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

public class FilterExample {

	public static void main(String[] args) {

		List studentList = new ArrayList();
		Student student = null;

		student = new Student();
		student.setId(1);
		student.setName("Rajesh");
		student.setAddress("Mumbai");
		studentList.add(student);

		student = new Student();
		student.setId(1);
		student.setName("Kumar");
		student.setAddress("Chennai");
		studentList.add(student);

		studentList.stream().filter(x -> x.getName().equals("Rajesh"))
		.forEach(x -> System.out.print(x.getAddress()));

	}

}

Person.java

public class Student {

	private int id;
	private String name;
	private String address;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

}

Output

Mumbai

Reference

oracle docs

Iterate list using streams in java

iterate stream with index in Java8

Tags filter, java8, streams

collections java

Iterate list using streams in java

Post author By Rajesh Kumar
Post date February 5, 2020
No Comments on Iterate list using streams in java

In this example, we will learn about iterate list using streams in java with example
It was introduced on Java 8

Features of Streams

No Storage
we can do arithmetic operations
we can filter the data without removing.

Syntax

list.stream().forEach((x) -> {operations});

Example

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

public class IterateListUsingStreams {

    public static void main(String[] args) {
        List list = new ArrayList();
        list.add("Apple");
        list.add("Pineapple");
        list.add("Papaya");
        list.stream().forEach((x) -> System.out.println(x));
    }

}

Output

Apple
Pineapple
Papaya

Example with Pojo

Student.java

public class Student {

	private int id;
	private String name;
	private String address;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

}

IterateListUsingStreams2 .java

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

public class IterateListUsingStreams2 {

	public static void main(String[] args) {

		List studentList = new ArrayList();
		Student student = null;

		student = new Student();
		student.setId(1);
		student.setName("Rajesh");
		student.setAddress("Chennai");
		studentList.add(student);

		student = new Student();
		student.setId(1);
		student.setName("Kumar");
		student.setAddress("Chennai");
		studentList.add(student);

		studentList.stream().forEach((x) -> System.out.println("Student Id is "+x.getId()+" Name is "+x.getName()));

	}

}

Output

Student Id is 1 Name is Rajesh
Student Id is 1 Name is Kumar

References

https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html

GitHub

https://github.com/rkumar9090/BeginnersBug/blob/master/BegineersBug/src/com/geeks/example/IterateListUsingStreams.java

https://github.com/rkumar9090/BeginnersBug/blob/master/BegineersBug/src/com/geeks/example/IterateListUsingStreams2.java

iterate stream with index in Java8

ArrayList in java with example

Tags java8, streams

Syntax

Example

Output

Github

Related Articles

Syntax

Example

Student.java

Output

Related Article

Github

Syntax

Ascending Example

Output

Descending Example

Output

References

Related Articles

Syntax

Example

Person.java

Output

Reference

Related Articles

Features of Streams

Syntax

Example

Output

Example with Pojo

Student.java

IterateListUsingStreams2 .java

Output

References

GitHub

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