Java 8 – How to print an Arrays ?

September 13, 2021 SJ Collection, Java 8 0

In this article, we will see how to print elements of an Arrays

Read Various ways to iterate Arrays in Java – 5 ways

Different ways to print an Arrays :

  1. Prints type@alphaNumericCharacter of an Arrays
  2. Print by iterating an Arrays using for-loop
  3. Print by iterating an Arrays using enhanced for-each loop
  4. Print by iterating an Arrays using Stream.forEach() method
  5. Print by iterating an Arrays using Iterator interface
  6. Print an Arrays after converting to List interface
  7. Print an Arrays using Arrays.toString() method
  8. Print an Arrays using Arrays.deepToString() method

1. Prints type@alphaNumericCharacter of an Array :

  • If we try to print an Array straight-forward, then it will simply print type@randomAlphaNumeric of an Array
  • To check, whether elements are present or not and what are its contents, for that we need to iterate an Array or use Arrays class’ method

PrintArrayDirectly.java

package net.bench.resources.print.array;

public class PrintArrayDirectly {

	public static void main(String[] args) {

		// 1. Wrapper/Boxed Integer array
		Integer[] intArray = {1,2,3,4,5};

		// 1.1 print to console directly
		System.out.println("Integer[] array :- " + intArray);

		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.1 print to console directly
		System.out.println("String[] array :- " + stringArray);
	}
}

Output:

Integer[] array :- [Ljava.lang.Integer;@1db9742
String[] array :- [Ljava.lang.String;@106d69c

2. Print by iterating an Array using for-loop :

  • The easiest approach is to iterate an Array using traditional for-loop introduced in Java 1.0 version
  • This will print each elements of an Array 1-by-1 to console using index-position

PrintArrayUsingForLoop.java

package net.bench.resources.print.array;

public class PrintArrayUsingForLoop {

	public static void main(String[] args) {

		// 1. Wrapper/Boxed Integer array
		Integer[] intArray = {1,2,3,4,5};

		// 1.1 print using regular for-loop
		System.out.println("Integer[] array :- ");
		for(int index = 0; index < intArray.length; index++) {
			System.out.print(intArray[index] + " ");
		}

		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.1 print using regular for-loop
		System.out.println("\n\n\nString[] array :- \n");
		for(int index = 0; index < stringArray.length; index++) {
			System.out.println(stringArray[index]);
		}
	}
}

Output:

Integer[] array :- 
1 2 3 4 5 


String[] array :- 

Power
Motor
Chemical
Consumer
Steel

3. Print by iterating an Array using enhanced for-each loop :

  • This the next approach where we can iterate an Array using enhanced for-each loop introduced in Java 1.5 version
  • This will print each elements of an Array 1-by-1 to console
  • Note: this doesn’t provide explicit index-position unlike traditional for-loop

PrintArrayUsingEnhancedForLoop.java

package net.bench.resources.print.array;

public class PrintArrayUsingEnhancedForLoop {

	public static void main(String[] args) {

		// 1. primitive int[] array
		int[] intArray = {1,2,3,4,5};

		// 1.1 print using enhanced for-loop
		System.out.println("primitive int[] array :- ");

		for(int value : intArray) {
			System.out.print(value + " ");
		}

		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.1 print using enhanced for-loop
		System.out.println("\n\nString[] array :- ");

		for(String str : stringArray) {
			System.out.println(str);
		}
	}
}

Output:

primitive int[] array :- 
1 2 3 4 5 

String[] array :- 
Power
Motor
Chemical
Consumer
Steel

4. Print by iterating an Array using Stream.forEach() :

  • Latest addition is to use Stream’s forEach() method to iterate an Array which is introduced in Java 1.8 version
  • We can pass either Lambda Expression or Method reference to forEach() method to print values to console

PrintArrayUsingStreamForEachLoop.java

package net.bench.resources.print.array;

import java.util.Arrays;
import java.util.stream.Stream;

public class PrintArrayUsingStreamForEachLoop {

	public static void main(String[] args) {

		// 1. Wrapper/Boxed Integer array
		Integer[] intArray = {1,2,3,4,5};

		// 1.1 print using Java 8 Stream forEach loop
		System.out.println("Integer[] array :- ");

		// 1.2 Lambda expression
		Arrays
		.stream(intArray)
		.forEach(num -> System.out.println(num));


		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.1 print using Java 8 Stream forEach loop
		System.out.println("\n\nString[] array :- \n");

		// 2.2 Method reference
		Stream
		.of(stringArray)
		.forEach(System.out::println);
	}
}

Output:

Integer[] array :- 
1
2
3
4
5


String[] array :- 

Power
Motor
Chemical
Consumer
Steel

5. Print by iterating an Array using Iterator interface :

  • We can also get iterator after converting Array to a List
  • Then using while-loop (i.e.; hasNext() and next() methods) we can iterate/print Array elements to console

PrintArrayUsingIterator.java

package net.bench.resources.print.array;

import java.util.Arrays;
import java.util.Iterator;

public class PrintArrayUsingIterator {

	public static void main(String[] args) {

		// 1. Wrapper/Boxed Integer array
		Integer[] intArray = {1,2,3,4,5};

		// 1.1 get iterator after converting to list-view
		Iterator<Integer> iterator = Arrays
				.asList(intArray)
				.iterator();

		System.out.println("Integer[] array :- ");

		// 1.2 iterate using while loop
		while(iterator.hasNext()) {

			// 1.3 print to console
			System.out.println(iterator.next());  
		}  

		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.1 get iterator after converting to list-view
		Iterator<String> strIterator = Arrays
				.asList(stringArray)
				.iterator();

		System.out.println("\n\nString[] array :- \n");

		// 2.2 iterate using while loop
		while(strIterator.hasNext()) {

			// 2.3 print to console
			System.out.println(strIterator.next());  
		} 
	}
}

Output:

Integer[] array :- 
1
2
3
4
5


String[] array :- 

Power
Motor
Chemical
Consumer
Steel

6. Print an Array after converting to List :

  • First, convert Array to List using Arrays.asList(arr)
  • Print list values directly to console
  • Note: actually asList() method provide list-view of an Array

PrintArrayAfterConvertingToList.java

package net.bench.resources.print.array;

import java.util.Arrays;
import java.util.List;

public class PrintArrayAfterConvertingToList {

	public static void main(String[] args) {

		// 1. Wrapper/Boxed Integer array
		Integer[] intArray = {1,2,3,4,5};

		// 1.1 convert to list-view
		List<Integer> integerList = Arrays.asList(intArray);

		// 1.2 print to console
		System.out.println("Integer[] array :- " + integerList);


		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.1 convert to list-view
		List<String> stringList = Arrays.asList(stringArray);

		// 2.2 print to console
		System.out.println("\nString[] array :- " + stringList);
	}
}

Output:

Integer[] array :- [1, 2, 3, 4, 5]

String[] array :- [Power, Motor, Chemical, Consumer, Steel]

7. Print an Array using Arrays.toString() method :

  • This static method helps to convert Array to String
  • We can print values of an Array to console

PrintArrayUsingToString.java

package net.bench.resources.print.array;

import java.util.Arrays;

public class PrintArrayUsingToString {

	public static void main(String[] args) {

		// 1. Wrapper/Boxed Integer array
		Integer[] intArray = {1,2,3,4,5};

		// 1.1 print to console
		System.out.println("Integer[] array :- " 
				+ Arrays.toString(intArray));


		// 2. String array
		String[] stringArray = {
				"Power",
				"Motor",
				"Chemical",
				"Consumer",
				"Steel"
		};

		// 2.2 print to console
		System.out.println("\nString[] array :- " 
				+ Arrays.toString(stringArray));
	}
}

Output:

Integer[] array :- [1, 2, 3, 4, 5]

String[] array :- [Power, Motor, Chemical, Consumer, Steel]

8. Print an Array using Arrays.deepToString() method :

  • This is another static method helps to convert Array to String specifically for 2-dimentional Array
  • We can print values of an 2-D Array to console

Print2dArrayUsingDeepToString.java

package net.bench.resources.print.array;

import java.util.Arrays;

public class Print2dArrayUsingDeepToString {

	public static void main(String[] args) {

		// 1. 2-d double array
		double[][] dbl2dArray = {
				{10.7, 20.8}, 
				{30.9, 40.6}, 
				{50.5, 60.3}
		};

		// 1.1 print to console
		System.out.println("double[][] array :- " 
				+ Arrays.deepToString(dbl2dArray));


		// 2. 2-d String array
		String[][] str2dArray = {
				{"Sachin", "Sourav", "Dravid"}, 
				{"Yuvraj", "Kaif"}, 
				{"Dhoni", "Raina"},
				{"Kohli", "Jadeja", "Rohit", "Bumrah"}
		};

		// 2.1 print to console
		System.out.println("\nString[][] array :- " 
				+ Arrays.deepToString(str2dArray));
	}
}

Output:

double[][] array :- [
[10.7, 20.8], 
[30.9, 40.6], 
[50.5, 60.3]
]

String[][] array :- [
[Sachin, Sourav, Dravid], 
[Yuvraj, Kaif], 
[Dhoni, Raina], 
[Kohli, Jadeja, Rohit, Bumrah]
]

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References:

Happy Coding !!
Happy Learning !!

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