Tutoring comp sci, you experiment a lot. The tutor shares one. The java command, in Windows, anyway, seems to like a space between the directory and the filename you are running. java -cp f:/dir1/dir2 program_file not java -cp f:/dir1/dir2/program_file Source:…
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Category: java
Java: overriding methods: what it means, and rules about it
Tutoring Java programming, you might be asked to clarify about overriding. The tutor shares some thoughts. In Java, when you override a method, you either define its performance (give it a “body”), or else redefine (change) its performance . Case…
Java compile error: non-static method cannot be referenced from a static context – what causes it?
Tutoring Java programming, this error message might come up. The tutor talks about a couple of its causes. The message error: non-static method MethodX() cannot be referenced from a static context has a couple of causes I know: The class…
Java programming: constructors in subclasses
Tutoring Java programming, there are so many interesting facets to encounter. The tutor talks about a constructor of a subclass and the word super. Let’s imagine you write a subclass. Furthermore, let’s imagine the parent class (the superclass) has a…
Java: the meaning of * used with import
The tutor offers an interpretation of what the asterisk (aka, wildcard) means in an import statement. I’m not trained in Java, but do write experimental programs with it. Here are some ideas about the import statement, as I understand it:…
Computer science: JavaScript: null value, undefined type and value
The tutor comments on JavaScript null and undefined. Null, it seems, is often mentioned in computer science. Perhaps it’s used a little loosely: it might refer to the value read when there’s nothing there, or the value of a variable…
Comp Sci: command prompt testing (Windows 7): how to kill a runaway program
The tutor brings up a couple of “emergency procedures” for stopping a program. I don’t write many big programs; rather, I’ll often write a page or so of code (with lots of white space) to test a utility from a…
Java: why null might be used as an input parameter (aka argument)
The tutor looks into passing null as an argument. Sometimes, reading Java code, you encounter null being passed as an argument aka parameter: method0(null); Apparently, when a method expects an object parameter, but doesn’t (necessarily) use it, you can pass…
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