JAVA - How convert binary, hex, octal etc. to decimal

For converting from binary, hexadecimal, octal etc. to decimal, use function Integer.parseInt(). Second parameter is base.

String sText = "";
Integer iValue;
String sValue = "";
    
/* -- convert to dec */
    
iValue = Integer.parseInt( "100", 10 );    
sText += "dec(100) to dec = " + iValue.toString() + "\n";
    
iValue = Integer.parseInt( "100", 2 );    
sText += "bin(100) to dec = " + iValue.toString() + "\n";

iValue = Integer.parseInt( "100", 16 );    
sText += "hex(100) to dec = " + iValue.toString() + "\n";

iValue = Integer.parseInt( "ff", 16 );    
sText += "hex(ff) to dec = " + iValue.toString() + "\n";

/* result */
    
memo.setText( sText );      

Output: