Java Program to convert octal number to decimal number

Use the parseInt() method with the second parameter as 8 since it is the radix value. The parseInt() method has the following two forms.

static int parseInt(String s)
static int parseInt(String s, int radix)

To convert octal to decimal, use the 2nd syntax and add radix as 8, since octal radix is 8.

Integer.parseInt("25", 8)

The following is an example.

Example

 Live Demo

public class Demo {
   public static void main( String args[] ) {
      // converting to decimal
      System.out.println(Integer.parseInt("25", 8));
   }
}

Output

21