Is it possible to postpone function call binds to runtime in Java?

Question

Consider a simple case where I ask a user to select a fruit among 10 different fruits. Say the fruits are, apples, oranges, mangoes,... etc., If the user selects apples, I call apples(), if he selects mangoes, I call mangoes() and so on...

To select which function is to be called, I DON'T want to use a switch or if-else statements. How do I select which function is to be called during run-time?

NOTE : The programming language I am using is Java

Create an interface fruits then each class should inherit it, then use reflection API to instantiate... Try looking for dynamic binding in Java to understand it better. — AurA, Oct 11 '12 at 05:22
I just want to know how those methods can be called dynamically. For now, for the sake of simplicity, we can assume that I print the name of the fruit in those methods. — coder, Oct 11 '12 at 05:23
Possible duplicate of http://stackoverflow.com/questions/2882948/calling-a-method-named-string-at-runtime-in-java-and-c — venkatKA, Oct 11 '12 at 05:25
@Coder.. Don't forget to accept one of the answers that you like.. — Rohit Jain, Oct 11 '12 at 05:31

score 0 · Answer 1 · answered Oct 11 '12 at 05:24

Use Reflection. eg: Write all the functions in a class ; say com.sample.FruitStall Then use below code.

String className = "com.sample.FruitStall";
String methodName = "apple"; //here you will choose desired method
Object result;
Class<?> _class;
        try {
            _class = Class.forName(className);
        } catch (Exception e) {
            e.printStackTrace();
        }
            Object[] args = new Object[1];  // To Supply arguments to function
            result = _class.invokeMethod(methodName, args);

score 0 · Accepted Answer · answered Oct 11 '12 at 05:24

Use java Refection api to call function at runtime.

        Class noparams[] = {};
        Class cls = Class.forName("com.test.Fruit");
        Object obj = cls.newInstance();

        //call the printIt method
        Method method = cls.getDeclaredMethod("apples", noparams);
        method.invoke(obj, null);

score 0 · Answer 3 · answered Oct 11 '12 at 05:27

0

use the design pattern "Command". http://www.codeproject.com/Articles/186192/Command-Design-Pattern

hiding the details of the action it needs to perform.

answered Oct 11 '12 at 05:27

rbhawsar

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Is it possible to postpone function call binds to runtime in Java?

3 Answers3