Byte Wrapper Class

Byte wrapper class is used to create an object version of a primitive byte value.

Constructor of Byte wrapper class.

Constructor	Description
Byte(byte c)	Constructor of Byte wrapper class takes a primitive byte value.
Byte(String str)	Constructor of Byte wrapper class also takes a String equivalent of a byte value.

Note:

int

byte

Creating a Byte object

class A
{
public static void main(String... ar)
{
Byte b1 = new Byte((byte)10); //casting the default int value to byte.
Byte b2 = new Byte("10"); //Passing primitive byte as a String.
}
}

Reading a Byte wrapper class object.

By directly printing the Byte object.
Calling method, byteValue() of Byte wrapper class, which returns the primitive byte equivalent.

class A
{
public static void main(String... ar)
{

//In Java, by default any numeric non-floating value is of primitive int type, so its casting to byte will be required 
//it is sent to the constructor of the Byte wrapper class.

Byte b1 = new Byte((byte)10); //Boxing primitive byte in a wrapper Byte object.

System.out.println(b1);	//Unboxing the Byte object.


//Reading primitive byte out of Byte object using byteValue() method
Byte b2 = new Byte("10"); //Passing primitive byte as a String
System.out.println("b2.byteValue());
}
}

Output-

A
A

Some important methods of Byte wrapper class

Methods	Description
int compareTo(Byte b)	- Returns a zero if the invoked Byte object contains the same byte value as b. - Returns a positive value if the invoked Byte object contains greater value than b. - Returns a negative value if the invoked Byte object contains smaller value than b.
boolean equals(Object ob)	Returns a true if the invoked Byte object has same value as referred by ob, else false.
static byte parseByte(String s)	Returns a primitive byte value if String s could be converted to a valid byte value.
static Byte valueOf(byte b)	Returns a Byte object after converting it from primitive byte value, b.
short shortValue()	Returns an primitive short value after converting it from an invoked Byte object.
byte byteValue()	Returns an byte value after converting it from an invoked Byte object.
int intValue()	Returns an int value after converting it from an invoked Byte object.
long longValue()	Returns an long value after converting it from an invoked Byte object.
float floatValue()	Returns an float value after converting it from an invoked Byte object.
double doubleValue()	Returns an double value after converting it from an invoked Byte object.

Using compareTo() method to compare values in two Byte objects.

Method compareTo() takes a Byte class type object and it -

Returns a zero if the invoked Byte object contains the same value as b.
Returns the negative difference if the invoked Byte object contains a value smaller than b.
Returns the positive difference if the invoked Byte object contains a value greater than b.

class A
{
public static void main(String... ar)
{
Byte b1 = new Byte("10");       //Constructor accepting String value
Byte b2 = new Byte((byte)10);	  //casting an int to byte to pass to Constructor of Byte class.

System.out.println("Value in b1 = "+b1);
System.out.println("Value in b2 = "+b2);

System.out.println("Invoking b1 to compare with b2 : "+ b1.compareTo(b2));

Byte b3 = new Byte("20");
Byte b4 = new Byte((byte)25);

System.out.println("Value in b3 = "+b3);
System.out.println("Value in b4 = "+b4);

System.out.println("Invoking b3 to compare with b4 : "+ b3.compareTo(b4));

System.out.println("Invoking b4 to compare with b3 : "+ b4.compareTo(b3));
}
}

Output-

Value in b1 = 10
Value in b2 = 10
Invoking b1 to compare with b2 : 0
Value in b3 = 20
Value in b4 = 25
Invoking b3 to compare with b4 : -5
Invoking b4 to compare with b3 : 5

To convert a String to a primitive byte value using parseByte() method.

Method parseByte(), converts a string value which could be parse to a primitive byte value.

//Converting String to primitive byte value.

class A
{
public static void main(String... ar)
{
byte b1 = Byte.parseByte("10");
byte b2 = Byte.parseByte("100");
byte b3 = Byte.parseByte("50");

System.out.println("Primitive byte value in b1 : "+ b1);
System.out.println("Primitive byte value in b2 : "+ b2);
System.out.println("Primitive byte value in b3 : "+ b3);
}
}

Output-

Primitive byte value in b1 : 10
Primitive byte value in b2 : 100
Primitive byte value in b3 : 50

Exception when converting a String to Byte

Exception could be caused in the following situations -

When we pass a String value to the constructor of Byte class or its method parseByte(), which cannot be converted to a Byte object.

//Converting String to object of Byte class by passing it to constructor of Byte class.

class A
{
public static void main(String... ar)
{
Byte b1 = new Byte("hh"); //Passing a String value to Byte class which can't be parsed to byte.

System.out.println("Primitive byte value in b1 : "+ b1);
}
}

Output -

Exception in thread "main" java.lang.NumberFormatException: For input string: "hh"
        at java.lang.NumberFormatException.forInputString(Unknown Source)
        at java.lang.Integer.parseInt(Unknown Source)
        at java.lang.Byte.parseByte(Unknown Source)
        at java.lang.Byte.(Unknown Source)
        at A.main(Byte8.java:7)

Trying to store an out-of-range value by passing it in the form of a string to constructor or parseByte() method of Byte class returns a NumberFormatException.

//Converting String to primitive byte value by passing it to parseShort() method.

class A
{
public static void main(String... ar)
{
byte b1 = Byte.parseByte("-128"); //last negative range of a byte valuev
byte b2 = Byte.parseByte("-129"); //Passing a String value beyond the range of byte 

System.out.println("Primitive byte value in b1 : "+ b1);
System.out.println("Primitive byte value in b2 : "+ b2);
}
}

Output -

Exception in thread "main" java.lang.NumberFormatException: Value out of range.
Value:"-129" Radix:10
        at java.lang.Byte.parseByte(Unknown Source)
        at java.lang.Byte.parseByte(Unknown Source)
        at A.main(Short6.java:8)

Converting the value stored in a Byte object to all numeric primitive types.

//Converting Byte to short, int, long, float, double

class A
{
public static void main(String... ar)
{
Byte y = new Byte("10"); // Converting a String argument to wrapped Integer object

System.out.println("Value in wrapped object,y "+ y);

byte b = y.byteValue();		//Returns a primitive byte value out of a wrapped Byte object
short s= y.shortValue();	//Returns a primitive short value out of a wrapped Byte object
int i = y.intValue();		//Returns a primitive int value out of a wrapped Byte object
long l = y.longValue();		//Returns a primitive long value out of a wrapped Byte object
float f = y.floatValue();	//Returns a primitive float value out of a wrapped Byte object
double d = y.doubleValue();	//Returns a primitive double value out of a wrapped Byte object



System.out.println("byte value of Byte object, y :" + b);
System.out.println("short value of Byte object, y:" + s);
System.out.println("int value of Byte object, y :" + i);
System.out.println("long value of Byte object, y :" + l);
System.out.println("float value of Byte object, y :" + f);
System.out.println("double value of Byte object, y :"+ d);

}
}

Output-

Value in wrapped object,y 10
byte value of Byte object, y :10
short value of Byte object, y:10
int value of Byte object, y :10
long value of Byte object, y :10
float value of Byte object, y :10.0
double value of Byte object, y :10.0

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