Java provides a class Base64 to deal with encryption. You can encrypt and decrypt your data by using provided methods. You need to import java.util.Base64 in your source file to use its methods.
This class provides three different encoders and decoders to encrypt information at each level. You can use these methods at the following levels.

Table of Contents

Basic Encoding and Decoding

It uses the Base64 alphabet specified by Java in RFC 4648 and RFC 2045 for encoding and decoding operations. The encoder does not add any line separator character. The decoder rejects data that contains characters outside the base64 alphabet.

URL and Filename Encoding and Decoding

It uses the Base64 alphabet specified by Java in RFC 4648 for encoding and decoding operations. The encoder does not add any line separator character. The decoder rejects data that contains characters outside the base64 alphabet.

MIME

It uses the Base64 alphabet as specified in RFC 2045 for encoding and decoding operations. The encoded output must be represented in lines of no more than 76 characters each and uses a carriage return ‘\r’ followed immediately by a linefeed ‘\n’ as the line separator. No line separator is added to the end of the encoded output. All line separators or other characters not found in the base64 alphabet table are ignored in decoding operation.

Nested Classes of Base64

Class	Description
Base64.Decoder	This class implements a decoder for decoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
Base64.Encoder	This class implements an encoder for encoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.

Base64 Methods

Methods	Description
public static Base64.Decoder getDecoder()	It returns a Base64.Decoder that decodes using the Basic type base64 encoding scheme.
public static Base64.Encoder getEncoder()	It returns a Base64.Encoder that encodes using the Basic type base64 encoding scheme.
public static Base64.Decoder getUrlDecoder()	It returns a Base64.Decoder that decodes using the URL and Filename safe type base64 encoding scheme.
public static Base64.Decoder getMimeDecoder()	It returns a Base64.Decoder that decodes using the MIME type base64 decoding scheme.
public static Base64.Encoder getMimeEncoder()	It Returns a Base64.Encoder that encodes using the MIME type base64 encoding scheme.
public static Base64.Encoder getMimeEncoder(int lineLength, byte[] lineSeparator)	It returns a Base64.Encoder that encodes using the MIME type base64 encoding scheme with specified line length and line separators.
public static Base64.Encoder getUrlEncoder()	It returns a Base64.Encoder that encodes using the URL and Filename safe type base64 encoding scheme.

Base64.Decoder Methods

Methods	Description
public byte[] decode(byte[] src)	It decodes all bytes from the input byte array using the Base64 encoding scheme, writing the results into a newly-allocated output byte array. The returned byte array is of the length of the resulting bytes.
public byte[] decode(String src)	It decodes a Base64 encoded String into a newly-allocated byte array using the Base64 encoding scheme.
public int decode(byte[] src, byte[] dst)	It decodes all bytes from the input byte array using the Base64 encoding scheme, writing the results into the given output byte array, starting at offset 0.
public ByteBuffer decode(ByteBuffer buffer)	It decodes all bytes from the input byte buffer using the Base64 encoding scheme, writing the results into a newly-allocated ByteBuffer.
public InputStream wrap(InputStream is)	It returns an input stream for decoding Base64 encoded byte stream.

Base64.Encoder Methods

public byte[] encode(byte[] src)	It encodes all bytes from the specified byte array into a newly-allocated byte array using the Base64 encoding scheme. The returned byte array is of the length of the resulting bytes.
public int encode(byte[] src, byte[] dst)	It encodes all bytes from the specified byte array using the Base64 encoding scheme, writing the resulting bytes to the given output byte array, starting at offset 0.
public String encodeToString(byte[] src)	It encodes the specified byte array into a String using the Base64 encoding scheme.
public ByteBuffer encode(ByteBuffer buffer)	It encodes all remaining bytes from the specified byte buffer into a newly-allocated ByteBuffer using the Base64 encoding scheme. Upon return, the source buffer’s position will be updated to its limit; its limit will not have been changed. The returned output buffer’s position will be zero and its limit will be the number of resulting encoded bytes.
public OutputStream wrap(OutputStream os)	It wraps an output stream for encoding byte data using the Base64 encoding scheme.
public Base64.Encoder withoutPadding()	It returns an encoder instance that encodes equivalently to this one, but without adding any padding character at the end of the encoded byte data.

Java Base64 Example: Basic Encoding and Decoding

1. import java.util.Base64; 
2. publicclass Base64BasicEncryptionExample { 
3. publicstaticvoid main(String[] args) { 
4. // Getting encoder 
5. Base64.Encoder encoder = Base64.getEncoder(); 
6. // Creating byte array 
7. bytebyteArr[] = {1,2}; 
8. // encoding byte array 
9. bytebyteArr2[] = encoder.encode(byteArr); 
10. System.out.println("Encoded byte array: "+byteArr2); 
11. bytebyteArr3[] = newbyte[5]; // Make sure it has enough size to store copied bytes 
12. intx = encoder.encode(byteArr,byteArr3); // Returns number of bytes written 
13. System.out.println("Encoded byte array written to another array: "+byteArr3); 
14. System.out.println("Number of bytes written: "+x); 
15. 
16. // Encoding string 
17. String str = encoder.encodeToString("Tecklearn".getBytes()); 
18. System.out.println("Encoded string: "+str); 
19. // Getting decoder 
20. Base64.Decoder decoder = Base64.getDecoder(); 
21. // Decoding string 
22. String dStr = new String(decoder.decode(str)); 
23. System.out.println("Decoded string: "+dStr); 
24. } 
25. }

Output:
Encoded byte array: [B@6bc7c054
Encoded byte array written to another array: [B@232204a1
Number of bytes written: 4
Encoded string: SmF2YVRwb2ludA==
Decoded string: Tecklearn

Java Base64 Example: URL Encoding and Decoding

1. import java.util.Base64; 
2. publicclass Base64BasicEncryptionExample { 
3. publicstaticvoid main(String[] args) { 
4. // Getting encoder 
5. Base64.Encoder encoder = Base64.getUrlEncoder(); 
6. // Encoding URL 
7. String eStr = encoder.encodeToString("http://www.tecklearn.com/java-section/".getBytes()); 
8. System.out.println("Encoded URL: "+eStr); 
9. // Getting decoder 
10. Base64.Decoder decoder = Base64.getUrlDecoder(); 
11. // Decoding URl 
12. String dStr = new String(decoder.decode(eStr)); 
13. System.out.println("Decoded URL: "+dStr); 
14. } 
15. }

Output:
Encoded URL: aHR0cDovL3d3dy5qYXZhdHBvaW50LmNvbS9qYXZhLXR1dG9yaWFsLw==
Decoded URL: http://www.tecklearn.com/java-section/

Java Base64 Example: MIME Encoding and Decoding

1. package Base64Encryption; 
2. import java.util.Base64; 
3. publicclass Base64BasicEncryptionExample { 
4. publicstaticvoid main(String[] args) { 
5. // Getting MIME encoder 
6. Base64.Encoder encoder = Base64.getMimeEncoder(); 
7. String message = "Hello, \nYou are informed regarding your inconsistency of work"; 
8. String eStr = encoder.encodeToString(message.getBytes()); 
9. System.out.println("Encoded MIME message: "+eStr); 
10. 
11. // Getting MIME decoder 
12. Base64.Decoder decoder = Base64.getMimeDecoder(); 
13. // Decoding MIME encoded message 
14. String dStr = new String(decoder.decode(eStr)); 
15. System.out.println("Decoded message: "+dStr); 
16. } 
17. }

Output:
Encoded MIME message: SGVsbG8sIApZb3UgYXJlIGluZm9ybWVkIHJlZ2FyZGluZyB5b3VyIGluY29uc2lzdGVuY3kgb2Yg
d29yaw==
Decoded message: Hello,
You are informed regarding your inconsistency of work

Java Default Methods

Java provides a facility to create default methods inside the interface. Methods which are defined inside the interface and tagged with default are known as default methods. These methods are non-abstract methods.

Java Default Method Example

In the following example, Sayable is a functional interface that contains a default and an abstract method. The concept of default method is used to define a method with default implementation. You can override default method also to provide more specific implementation for the method.
Let’s see a simple

1. interface Sayable{ 
2. // Default method 
3. default void say(){ 
4. System.out.println("Hello, this is default method"); 
5. } 
6. // Abstract method 
7. void sayMore(String msg); 
8. } 
9. public class DefaultMethods implements Sayable{ 
10. public void sayMore(String msg){ // implementing abstract method 
11. System.out.println(msg); 
12. } 
13. public static void main(String[] args) { 
14. DefaultMethods dm = new DefaultMethods(); 
15. dm.say(); // calling default method 
16. dm.sayMore("Work is worship"); // calling abstract method 
17. 
18. } 
19. }

Output:
Hello, this is default method
Work is worship

Static Methods inside Java 8 Interface

You can also define static methods inside the interface. Static methods are used to define utility methods. The following example explain, how to implement static method in interface?

1. interface Sayable{ 
2. // default method 
3. default void say(){ 
4. System.out.println("Hello, this is default method"); 
5. } 
6. // Abstract method 
7. void sayMore(String msg); 
8. // static method 
9. static void sayLouder(String msg){ 
10. System.out.println(msg); 
11. } 
12. } 
13. public class DefaultMethods implements Sayable{ 
14. public void sayMore(String msg){ // implementing abstract method 
15. System.out.println(msg); 
16. } 
17. public static void main(String[] args) { 
18. DefaultMethods dm = new DefaultMethods(); 
19. dm.say(); // calling default method 
20. dm.sayMore("Work is worship"); // calling abstract method 
21. Sayable.sayLouder("Helloooo..."); // calling static method 
22. } 
23. }

Output:
Hello there
Work is worship
Helloooo…

Abstract Class vs Java 8 Interface

After having default and static methods inside the interface, we think about the need of abstract class in Java. An interface and an abstract class is almost similar except that you can create constructor in the abstract class whereas you can’t do this in interface.

1. abstract class AbstractClass{ 
2. public AbstractClass() { // constructor 
3. System.out.println("You can create constructor in abstract class"); 
4. } 
5. abstract int add(int a, int b); // abstract method 
6. int sub(int a, int b){ // non-abstract method 
7. return a-b; 
8. } 
9. static int multiply(int a, int b){ // static method 
10. return a*b; 
11. } 
12. } 
13. public class AbstractTest extends AbstractClass{ 
14. public int add(int a, int b){ // implementing abstract method 
15. return a+b; 
16. } 
17. public static void main(String[] args) { 
18. AbstractTest a = new AbstractTest(); 
19. int result1 = a.add(20, 10); // calling abstract method 
20. int result2 = a.sub(20, 10); // calling non-abstract method 
21. int result3 = AbstractClass.multiply(20, 10); // calling static method 
22. System.out.println("Addition: "+result1); 
23. System.out.println("Substraction: "+result2); 
24. System.out.println("Multiplication: "+result3); 
25. } 
26. }

Output:
You can create constructor in abstract class
Addition: 30
Substraction: 10
Multiplication: 200

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