Creating data structure in Java

Question

I'm wondering if there is a good way to create a new data structure in Java that avoids creating new class file. According to this post, the Java's equivalence to struct in C is simply a class. However I find it redundant to create a whole new file for a class that simply have a couple of public fields, ex: x,y coordinates of a point. In C, the data structure can be defined within the .c file that uses it, which is a lot more simple. Is this actually the only way in Java?

Use inner classes or multiple classes within the same .java file (of course, with only one public class). But this will still create multiple class files. — Sudhanshu Umalkar, Mar 29 '13 at 08:22

score 4 · Accepted Answer · answered Mar 29 '13 at 08:24

4

You could use inner/nested classes. You'll have only one .java file, but nested classes will all have their own .class file when compiling.

answered Mar 29 '13 at 08:24

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score 4 · Answer 2 · answered Mar 29 '13 at 08:24

You have to create a class if you want a data structure. Just to avoid creating multiple .java files, you can put those classes in a single .java file. Assuming, Test.java-

public class Test {

    class InnerOne {
    }

    void m() {
        class InnerMost {
        }
    }
}

class Dummy {
}

class OnMore {
}

score 1 · Answer 3 · answered Mar 29 '13 at 08:23

You can create several small, auxiliary classes in one .java file, but they can not be public. So for example you can create a public class, whose name corresponds to a file and a couple of helper classes that are not public.

As for class per data structure in java, java has only one way of creating abstract data types - classes, if you're not satisfied with this - try using other JVM languages, like Scala, it is far more flexible in this regard.

score 0 · Answer 4 · answered Mar 29 '13 at 08:22

Java is an Object Oriented Programming language, so everything works with classes and you should not try to program with Java as with C.

If you want to define a data structure within a class, you should use InnerClass, there is a good example on the official documentation.

Creating data structure in Java

4 Answers4