text: another java program error..it says operator can not be applied to java.lang.double, java.lang.double!!! help! import java.io.*; public class thirdprogram {  public static void main(string args[]) throws exception { string snumber; double dnumber, dsquare, dcube; bufferedreader br = new bufferedreader(new inputstreamreader(system.in)); system.out.print ("input an integer: "); snumber = br.readline(); dnumber = double.parsedouble(snumber); dsquare = dnumber*dnumber; dcube = dnumber*dnumber*dnumber; system.out.println ("the square of" + dnumber + "is" + dsquare); system.out.println ("the cube of" + dnumber + "is" + dcube); } }  whats the problem with this one??it says operator can not be applied to java.lang.double, java.lang.double use double, not double.  you can't use the arithmetic operators you would normally use on primitives (i.e. double) on objects (i.e. double). one solution would be to convert your double objects into doubles using the doublevalue() method and do your calculations on those.