Java.Lang.Byte class in Java

In Java, Byte class is a wrapper class for the primitive type byte which contains several methods to effectively deal with a byte value like converting it to a string representation, and vice-versa. An object of the Byte class can hold a single byte value.

Constructors of Byte Class

There are mainly two constructors to initialize a Byte object-

1. Byte(byte b)

Creates a Byte object initialized with the value provided.

Syntax:  
public Byte(byte b)

Parameters :
b : value with which to initialize

2. Byte(String s)

Creates a Byte object initialized with the byte value provided by string representation. The default radix is taken to be 10.

Syntax : 
public Byte(String s) throws NumberFormatException

Parameters :
s : string representation of the byte value 

Throws :
NumberFormatException : If the string provided does not represent any byte value.

Fields in Java Byte class

1. static int BYTES: The number of bytes used to represent a byte value in two’s complement binary form.
2. static byte MAX_VALUE: A constant holding the maximum value a byte can have, 27-1.
3. static byte MIN_VALUE: A constant holding the minimum value a byte can have, -27.
4. static int SIZE: The number of bits used to represent a byte value in two’s complement binary form.
5. static Class<Byte> TYPE: The Class instance representing the primitive type byte.

Methods in Java Byte Class

1. toString()

The toString() function returns the string corresponding to the byte value.

Syntax : 
public String toString(byte b)

Parameters :
b : byte value for which string representation required.

2. valueOf() :

This function returns the Byte object initialized with the value provided.

Syntax : public static Byte valueOf(byte b)

Parameters :
b : a byte value

3. valueOf(String val,int radix) 

Another overloaded function valueOf(String val,int radix) which provides function similar to new Byte(Byte.parseByte(val,radix))

Syntax : 
public static Byte valueOf(String val, int radix)
throws NumberFormatException

Parameters :
val : String to be parsed into byte value
radix : radix to be used while parsing

Throws :
NumberFormatException : if String cannot be parsed to a byte value in given radix.

4. valueOf(String val)

Another overloaded function valueOf(String val) which provides function similar to new Byte(Byte.parseByte(val,10))

Syntax : 
 public static Byte valueOf(String s)
 throws NumberFormatException
           
Parameters :
s : a String object to be parsed as byte

Throws :
NumberFormatException : if String cannot be parsed to a byte value in given radix.

5. parseByte()

Returns byte value by parsing the string in radix provided. Differs from valueOf() as it returns a primitive byte value and valueOf() return Byte object.

Syntax : 
    public static byte parseByte(String val, int radix)
    throws NumberFormatException

Parameters :
val : String representation of byte 
radix : radix to be used while parsing

Throws :
NumberFormatException : if String cannot be parsed to a byte value in given radix.

6. Another overloaded method containing only String as a parameter, radix is by default set to 10.

Syntax : 
 public static byte parseByte(String val)
 throws NumberFormatException

Parameters :
val : String representation of byte 

Throws :
NumberFormatException : if String cannot be parsed to a byte value in given radix.

7. decode():

returns a Byte object holding the decoded value of the string provided. String provided must be of the following form else NumberFormatException will be thrown- Decimal- (Sign)Decimal_Number Hex- (Sign)”0x”Hex_Digits Hex- (Sign)”0X”Hex_Digits Octal- (Sign)”0″Octal_Digits

Syntax : 
 public static Byte decode(String s)
 throws NumberFormatException

Parameters :
s : encoded string to be parsed into byte val

Throws :
NumberFormatException : If the string cannot be decoded into a byte value

8. byteValue()

The byteValue() function returns a byte value corresponding to this Byte Object.

Syntax : public byte byteValue()

9. shortValue()

returns a short value corresponding to this Byte Object.

Syntax : public short shortValue()

10. intValue()

The intValue() returns a int value corresponding to this Byte Object.

Syntax : public int intValue()

11. longValue()

The longValue() function returns a long value corresponding to this Byte Object.

Syntax : public long longValue()

12. doubleValue()

returns a double value corresponding to this Byte Object.

Syntax : public double doubleValue()

13. floatValue()

returns a float value corresponding to this Byte Object.

Syntax : public float floatValue()

14. hashCode()

The hashCode() method returns the hashcode corresponding to this Byte Object.

Syntax : public int hashCode()

15. equals()

It is used to compare the equality of two Byte objects. The equals() methods returns true if both the objects contains same byte value. Should be used only if checking for equality. In all other cases compareTo method should be preferred.

Syntax : 
    public boolean equals(Object obj)

Parameters :
obj : object to compare with

16. compareTo()

The compareTo() is used to compare two Byte objects for numerical equality. This should be used when comparing two Byte values for numerical equality as it would differentiate between less and greater values. Returns a value less than 0,0,value greater than 0 for less than,equal to and greater than.

Syntax : 
 public int compareTo(Byte b)

Parameters :
b : Byte object to compare with

17. compare()

The compare() method compares two primitive byte values for numerical equality. As it is a static method therefore it can be used without creating any object of Byte.

Syntax : 
public static int compare(byte x,byte y)

Parameters :
x : byte value
y : another byte value

Java

// Java program to illustrate
// various methods of Byte class
public class Byte_test {
    public static void main(String[] args)
    {

        byte b = 55;
        String bb = "45";

        // Construct two Byte objects
        Byte x = new Byte(b);
        Byte y = new Byte(bb);

        // toString()
        System.out.println("toString(b) = "
                           + Byte.toString(b));

        // valueOf()
        // return Byte object
        Byte z = Byte.valueOf(b);
        System.out.println("valueOf(b) = " + z);
        z = Byte.valueOf(bb);
        System.out.println("ValueOf(bb) = " + z);
        z = Byte.valueOf(bb, 6);
        System.out.println("ValueOf(bb,6) = " + z);

        // parseByte()
        // return primitive byte value
        byte zz = Byte.parseByte(bb);
        System.out.println("parseByte(bb) = " + zz);
        zz = Byte.parseByte(bb, 6);
        System.out.println("parseByte(bb,6) = " + zz);

        // decode()
        String decimal = "45";
        String octal = "005";
        String hex = "0x0f";

        Byte dec = Byte.decode(decimal);
        System.out.println("decode(45) = " + dec);
        dec = Byte.decode(octal);
        System.out.println("decode(005) = " + dec);
        dec = Byte.decode(hex);
        System.out.println("decode(0x0f) = " + dec);

        System.out.println("bytevalue(x) = "
                           + x.byteValue());
        System.out.println("shortvalue(x) = "
                           + x.shortValue());
        System.out.println("intvalue(x) = " + x.intValue());
        System.out.println("longvalue(x) = "
                           + x.longValue());
        System.out.println("doublevalue(x) = "
                           + x.doubleValue());
        System.out.println("floatvalue(x) = "
                           + x.floatValue());

        int hash = x.hashCode();
        System.out.println("hashcode(x) = " + hash);

        boolean eq = x.equals(y);
        System.out.println("x.equals(y) = " + eq);

        int e = Byte.compare(x, y);
        System.out.println("compare(x,y) = " + e);

        int f = x.compareTo(y);
        System.out.println("x.compareTo(y) = " + f);
    }
}

Output

toString(b) = 55
valueOf(b) = 55
ValueOf(bb) = 45
ValueOf(bb,6) = 29
parseByte(bb) = 45
parseByte(bb,6) = 29
decode(45) = 45
decode(005) = 5
decode(0x0f) = 15
bytevalue(x) = 55
shortvalue(x) = 55
intvalue(x) = 55
longvalue(x) = 55
doublevalue(x) = 55.0
floatvalue(x) = 55.0
hashcode(x) = 55
x.equals(y) = false
compare(x,y) = 10
x.compareTo(y) = 10

References : Official Java Documentation