callback function Learning in Java

callback function Learning in Java Blog Category:

• J2se

Javaj# is generally divided into the following steps:

1. The unified interface for declaring a callback function is interface A, which contains the method callback ();
2. The interface is set to private members within the calling class caller.
3. The public method for implementing the A interface is provided within the caller (the implementation class of the external interface is passed through the formal parameter to the caller XXX);
4. The Xxx.callback () method is used in a caller method Dosth ();
5. In the example of caller, a interface is implemented first, then the Dosth () method is called.

Examples of popular online:
Java code

2. callback function interface and method
4. Public interface Icallback {
6. public void func ();
8. }
10. callback function interface Implementation class
12. Public class Classwithcallbackfunction implements icallback{
14. Public classwithcallbackfunction () {
16. }
18. public void func () {
20. System.out.println ("CCCCCCCCCCCCCCCCCC");
22. }
24. }
26. Public class Caller {
28. private Icallback callback; //Private interface member
30. public void Setcallback (Icallback callback) {
32. This.callback = callback; //interface member implementation: Incoming from the outside
34. }
36. public void DoCallback () { //Callback interface member method
38. Callback.func ();
40. }
42. }
44. }
46. Public class MainClass {
48. Public MainClass () {
50. }
52. public static void Main (string[] args) {
54. Caller Caller = new Caller ();
56. Caller.setcallback (new Classwithcallbackfunction () {
58. public void func () {
60. System.out.println ("aaaaaaaaaa");
62. }
64. });
66. Caller.docallback (); //Implementation callback
68. }
70. }
72. In reality, the DoCallback () method is placed in the Setcallback call, the above is to illustrate the callback principle
74. Public class Caller {
76. Icallback callback;
78. public void DoCallback () {
80. Callback.func ();
82. }
84. public void Setcallback (Icallback callback) {
86. This.callback = callback;
88. DoCallback ();
90. }
92. }

Another example is the Java sort compare interface

Java code

2. Interface Compare {
4. 　　　Boolean LessThan (Object LHS, object RHS);
6. 　　　Boolean Lessthanorequal (Object LHS, object RHS);
8. }
12. Import java.util.*;
16. 　　Public class Sortvector extends Vector {
18. 　　　Private Compare Compare; //Private interface member
20. 　　　Public Sortvector (Compare comp) {
22. compare = comp;
24. }
26. 　　　Public void Sort () {
28. QuickSort (0, size ()- 1);
30. }
32. 　　　Private void QuickSort (int left, int. right) {
34. if (right > left) {
36. Object O1 = ElementAt (right);
38. int i = left- 1;
40. int j = right;
42. While (true) {
44. While (Compare.lessthan (
46. ElementAt (++i), O1))
48. ;
50. While (J > 0)
52. if (compare.lessthanorequal (
54. ElementAt (--j), O1))
56. Break ;
58. if (i >= j) break ;
60. Swap (I, j);
62. }
64. Swap (I, right);
66. QuickSort (left, I-1);
68. QuickSort (i+1, right);
70. }
72. }
74. private void swap (int loc1, int loc2) {
76. Object tmp = ElementAt (LOC1);
78. Setelementat (ElementAt (LOC2), Loc1);
80. Setelementat (TMP, LOC2);
82. }
84. }

callback function Learning in Java