String conversions in java

String Data conversions:

• String variable can accept any type of data.
• Generally input always collect in string format only.
• We need to convert these string type values into corresponding primitive types before processing in application.
• For example, a text box collect input into text(String) type only.

Primitive to String: Following method in Byte class can be used to perform this conversion:

Conversion logic using above method as follows:

/*
class Byte
{
	public static byte parseByte(String s) throws NumberFormatException
		Parses the string argument as a signed decimal byte. 
}
*/
class StringToPrimitive
{
	public static void main(String[] args) 
	{
		String s = "100";
		byte b = Byte.parseByte(s);
		System.out.println("byte value is : " + b);
	}
}

Object to String conversion: Byte class is providing following method to convert Object to String

Conversion logic using above method as follows:

/*
class Byte
{
	public static Byte valueOf(byte b)
		Returns Byte object representing byte value.

	public String toString()
		Returns a String object representing this Byte's value. 
}
*/
class ObjectToString 
{
	public static void main(String[] args) 
	{
		byte b = 10;
		Byte obj = Byte.valueOf(b);
		String s = obj.toString();
		System.out.println("String value is : " + s);
	}
}

String to Primitive conversion:

• An important data conversion used in java application is String to Primitive.
• parseByte() method of Byte class can be used for this conversion.
• Parsing means “conversion”.

Conversion logic using above method as follows:

class StringToPrimitive
{
	public static void main(String[] args) 
	{
		String s = "10";
		byte b = Byte.parseByte(s);
	}
}

Exception: Runtime Error will occur if the input is not valid. How can we avoid exceptions will discuss later in Exception handling concept

class StringToPrimitive
{
	public static void main(String[] args) 
	{
		String s = "abc";
		byte b = Byte.parseByte(s); // Exception : Invalid input
	}
}

String to Object conversion: Byte class is providing class level method for this conversion.

Conversion logic using above method as follows:

/*class Byte
{
	public static Byte valueOf(String s)  throws NumberFormatException
		Returns a Byte object holding the value given by the specified String.
}*/

class StringToObject
{
	public static void main(String[] args) 
	{
		String s = "abc";
		Byte obj = Byte.valueOf(s);
		System.out.println("Byte value is : " + obj);
	}
}

Conversion using Byte class constructor:

class StringToObject 
{
	public static void main(String[] args) 
	{
		String s = "100" ;
		Byte b = new Byte(s);
	}
}