Java Integer decode() method

The decode() method is a static method of Integer class under java.lang package. The main function of this method is to decode a string which is written in the form of (" ") into an integer value.

The decode() method also accepts decimal, hexadecimal, and octal numbers. It is given by the following grammar:

DecodableString:

Sign_opt DecimalNumeral
Sign_opt 0x HexDigits
Sign_opt 0X HexDigits
Sign_opt # HexDigits
Sign_opt 0 OctalDigits

Sign:

-
+

This type of String will throw a NumberFormatException or represent a positive value. The result is negated if sign of the first character of the decodable String is minus. There are no whitespace characters are permitted in the String.

Syntax

Following is the declaration of decode() method:

Parameter:

DataType	Parameter	Description	Required/Optional
String	nm	The value which we want to decode into an Integer object	Required

Returns:

The decode() method returns an Integer object which hold the int value represented by String nm.

Exceptions:

NumberFormatException - This method throws an exception if the String does not contain an integer which can be parsed.

Compatibility Version:

Java 1.2 and above

Example 1

public class IntegerDecodeExample1 {
	public static void main(String[] args) {		
		// decode the string using base 8
		System.out.println(Integer.decode("0121"));				
		// decode the string using base 16				
		System.out.println(Integer.decode("0x114"));				
		// decode the string using base 16 signed				
		System.out.println(Integer.decode("-0x104"));
	}
}

Output:

81
276
-260

Example 2

public class IntegerDecodeExample2 {
	public static void main(String[] args) {
	    Integer i = new Integer(10);		
	    String str = "555";	      
	    //returns Integer object holding the int value represented by string str 
	    System.out.println(" Integer Number is = " +i.decode(str)); 
	}
}

Output:

Integer Number is = 555

Example 3

This is an example in which we pass the String value and it shows NumberFormatException.

public class IntegerDecodeExample3 {
	public static void main(String[] args) {
		Integer i = new Integer(10);		
		String str = "JavaTpoint";	      
	   // returns Integer object holding the int value represented by string str 
	      System.out.println(" Integer Number is = " + i.decode(str)); 
	}
}

Output:

Exception in thread "main"java.lang.NumberFormatException: For input string: "JavaTpoint"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:580)
	at java.lang.Integer.valueOf(Integer.java:740)
	at java.lang.Integer.decode(Integer.java:1197)
	at myPackage.DecodeMethodExample.main(DecodeMethodExample.java:8)

Example 4

import java.util.Scanner;
public class IntegerDecodeExample4 {
	public static void main(String[] args) {
		//Ask for user input
		System.out.print("Enter a value to decode: ");
		Scanner s = new Scanner(System.in);
		//assign the input to a variable
		String value = s.nextLine();
		// get the decode() method result
		Integer result = Integer.decode(value);
		//print the result
		System.out.println("Result:" + result);
		s.close();

	}
}

Output: