Question

I have always wondered:

• If I a have for example 8 JLabels named label1, label2, label3…
• I receive a message to show in one of them and an integer number from 1 to 8

Is there any smart way to access the variable named label+number without using a switch or a bunch of if-elses? And if so, is it more efficient than the switch/if-elses method?

I’m labeling for Java, but I think it is an interesting question for any classic language.

Answer 1

you can use reflection for it, but it will suffer from bad performance, or you can do it using a Map<Integer,JLabel>, which was precomputed with your objects.

For the more general case, reflection is probably what you are looking for.

Simple example of the usage of reflection:

public class TestSomething {
    public int elem1 = 1;
    public int elem2 = 2;
    public int elem3 = 3;
    public int elem4 = 4;
    public static void main(String[] str) throws NoSuchFieldException,IllegalAccessException {
        TestSomething test = new TestSomething();
        int num = 3;
        Field field = test.getClass().getField("elem" + num);
        System.out.println(field.get(test));
    }
}