[Practice] Java callback Functions

The following uses the Java callback function to implement a tool class for testing the function runtime:

If we want to test the execution time of a class method, we usually do this:

Java code

1. Public class testobject {
2. /**
3. * A method used for testing carries out a time-consuming cycle.
4. */
5. Public static void testmethod (){
6. For (INT I = 0; I <100000000; I ++ ){
8. }
9. }
10. /**
11. * A Simple Method for Testing the execution time
12. */
13. Public void testTime (){
14. Long begin = System. currentTimeMillis (); // Test start time
15. TestMethod (); // Test Method
16. Long end = System. currentTimeMillis (); // test end Time
17. System. out. println ("[use time]:" + (end-begin); // print the usage time
18. }
20. Public static void main (String [] args ){
21. TestObject test = new TestObject ();
22. Test. testTime ();
23. }
24. }

As you can see, only the "// test method" of the testtime () method needs to be changed. Let's create a function to implement the same function but be more flexible:

First, define a callback interface:

Java code

1. Public interface CallBack {
2. // Method for executing the callback operation
3. Void execute ();
4. }

Then write a tool class:

Java code

1. Public class Tools {
3. /**
4. * Test the function usage time by defining the execute method of the CallBack Interface
5. * @ Param callBack
6. */
7. Public void testTime (CallBack callBack ){
8. Long begin = System. currentTimeMillis (); // Test start time
9. CallBack.exe cute (); // call back
10. Long end = System. currentTimeMillis (); // test end Time
11. System. Out. println ("[use time]:" + (end-begin); // print the usage time
12. }
14. Public static void main (string [] ARGs ){
15. Tools tool = new tools ();
16. Tool. testtime (New callback (){
17. // Define the execute Method
18. Public void execute (){
19. // Add one or more methods to test the running time.
20. TestObject. testMethod ();
21. }
22. });
23. }
25. }

As you can see, the callback function can be implemented by passing testtime () to the execute () method that defines the callback interface.

 

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