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Java, macro code, function address

开发者 https://www.devze.com 2023-02-14 16:47 出处:网络
I am beginner with Java, and I would like to write some code like this : TEST(myfunction(1, 2, 3)); Where TEST is :

I am beginner with Java, and I would like to write some code like this :

TEST(myfunction(1, 2, 3));

Where TEST is :

  • Either a macro as used in C
  • Either a function which need the address of the function myfunction

In my code, I would like TEST to do some code :

TEST(function) {
    if (function()) 
        // code
    else
        //code
}

I know pointers are not usable in Java. An idea to help me ?

[EDIT] Here is another example :

TEST(myfunction(1, 2, 3));

Where T开发者_运维技巧EST is implemented :

void TEST (function(args[])) {
try {
    function();
}
catch (Exception e) {
    // Exception happened !
}

}

Thanks to that, with only one code line, I will be able to use try catch !


Java doesn't have pointers to functions. The typical way functions are passed around in Java is to pass an object that implements Runnable.

EDIT: I've revised my example to be closer to your second case.

In your case, where you want a boolean return value, you can define your own interface:

public interface BooleanTest {
    boolean test(Object... args) throws Exception;
}

and then later:

class MyTest implements BooleanTest {
    private boolean result;
    public MyTest(int a, int b, int c) {
        result = a + b == c;
    }
    // stupid test -- don't _have_ to declare "throws Exception"
    public boolean test(Object... args) {
        return result && args.length == 3;
    }
}

TEST(new MyTest(1, 2, 3));

and inside TEST:

TEST(BooleanTest test) {
    try {
        if (test.test("Jack", "and", "Jill")) {
            // ...
        }
    } catch (Exception e) {
    }
}


You need to get an interface implementation as a parameter. Like this:

public static void testFunction(new FunctionContainer() {

  @Override
  public int function() {
    ...
  }

};);


You can't really do this in java as methods are not Objects. To achieve your desired functionality you would need to wrap your function/method inside another object.

 // Define a function interface that your test method takes as an argument.
 public interface Function {
     public abstract void doFunction();
 }

 // Test code
 public void test(Function function) {
     function.doFunction();
 }

 // You can then pass an implementation of Function to your test method
 test(new Function() {
     public void doFunction() {
         // Function implementation
     }
  });
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