|Question: One of the steps in the instructions suggests to change FrameSequence variable 'frames' to static. I changed this at the very top of the file under data storage section to read |
static frames;but when I try to compile, I get this error in line 4:
Error: C:\CS1316\java-source-Fall06\WalkingSausageMan.java:4: <identifier> expectedAny idea what's wrong?
I guess that didn't copy with the brackets, but the error says <_identifier_> expected (where the underscores are not present nor are spaces in Dr. Java error message.
static FrameSequence framesDawn Finney
|Question: In my renderScene, the first line (after the "public" line) is currently |
ColoringPicture pic = new ColoringPicture(name, t+2);When I try to compile it, I get the error:
File: /Applications/DrJava/WalkingSausageMan.java [line: 15] Error: cannot find symbol symbol : constructor ColoringPicture(java.lang.String,int) location: class ColoringPictureThe same thing happens when I take the unmodified PurplePicture and try to run it. Any ideas? The ColoringPicture.java compiles and runs OK.
ColoringPicture pic = new ColoringPicture(name, t+2);is attempting to call the constructor with two parameters. Instead, your call should be
ColoringPicture pic = new ColoringPicture(name);(where you must define your variable name before the call). Student1086
|Question: I am getting a NullPointerException error every time I try to run my code and it forces me to restart Dr. Java. What could be causing this?|
String testString = null; System.out.println(testString.toString()); //NullPointerException occurs hereThe problem here is that I am calling a method on an Object that is null. null is essentially a placeholder for an actual Object and is not capable of any actions. So when you call a method on testString who is null, it just goes "Nope. Can't do that" and throws the exception.
String testString = null; System.out.println(testString); System.out.println(testString.toString());Another similar example:
intarray = null; for(int i = 0; i < array.length; i++) //NullPointerException occurs here System.out.println(array[i]);Using my method for testing/debugging, the above code would be:
intarray = null; System.out.println(array); for(int i = 0; i < array.length; i++) //NullPointerException occurs here System.out.println(array[i]);It is important to note in this case that we are not trying to call a method on the Object but will still yield a NullPointerException
|Question: I am trying to use custom colors in my code, but some colors don't seem to work. For instance, |
new Color(50,0,50)turns out black rather than dark purple, and
new Color(250,100,0)comes out red instead of orange. Is there a predefined color table that Java is automatically snapping my colors to?