Java多線程通信之兩個線程分別打印AB各10次，java多線程
一道經典的面試題目：兩個線程，分別打印AB，其中線程A打印A，線程B打印B，各打印10次，使之出現ABABABABA.. 的效果
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1 package com.shangshe.path;
2
3 public class ThreadAB {
4
5 /**
6 * @param args
7 */
8 public static void main(String[] args) {
9
10 final Print business = new Print();
11
12 new Thread(new Runnable() {
13 public void run() {
14 for(int i=0;i<10;i++) {
15 business.print_A();
16 }
17 }
18 }).start();
19
20 new Thread(new Runnable() {
21 public void run() {
22 for(int i=0;i<10;i++) {
23 business.print_B();
24 }
25 }
26 }).start();
27
28 }
29 }
30 class Print {
31
32 private boolean flag = true;
33
34 public synchronized void print_A () {
35 while(!flag) {
36 try {
37 this.wait();
38 } catch (InterruptedException e) {
39 // TODO Auto-generated catch block
40 e.printStackTrace();
41 }
42 }
43 System.out.print("A");
44 flag = false;
45 this.notify();
46 }
47
48 public synchronized void print_B () {
49 while(flag) {
50 try {
51 this.wait();
52 } catch (InterruptedException e) {
53 // TODO Auto-generated catch block
54 e.printStackTrace();
55 }
56 }
57 System.out.print("B");
58 flag = true;
59 this.notify();
60 }
61 }
View Code
由上面的例子我們可以設計出3個線程乃至於n個線程的程序，下面給出的例子是3個線程，分別打印A，B，C 10次，使之出現ABCABC.. 的效果
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1 public class ThreadABC {
2
3 /**
4 * @param args
5 */
6 public static void main(String[] args) {
7
8 final Print business = new Print();
9
10 new Thread(new Runnable() {
11 public void run() {
12 for(int i=0;i<100;i++) {
13 business.print_A();
14 }
15 }
16 }).start();
17
18 new Thread(new Runnable() {
19 public void run() {
20 for(int i=0;i<100;i++) {
21 business.print_B();
22 }
23 }
24 }).start();
25
26 new Thread(new Runnable() {
27 public void run() {
28 for(int i=0;i<100;i++) {
29 business.print_C();
30 }
31 }
32 }).start();
33
34 }
35 }
36 class Print {
37
38 private boolean should_a = true;
39 private boolean should_b = false;
40 private boolean should_c = false;
41
42 public synchronized void print_A () {
43 while(should_b || should_c) {
44 try {
45 this.wait();
46 } catch (InterruptedException e) {
47 // TODO Auto-generated catch block
48 e.printStackTrace();
49 }
50 }
51 System.out.print("A");
52 should_a = false;
53 should_b = true;
54 should_c = false;
55 this.notifyAll();
56 }
57
58 public synchronized void print_B () {
59 while(should_a || should_c) {
60 try {
61 this.wait();
62 } catch (InterruptedException e) {
63 // TODO Auto-generated catch block
64 e.printStackTrace();
65 }
66 }
67 System.out.print("B");
68 should_a = false;
69 should_b = false;
70 should_c = true;
71 this.notifyAll();
72 }
73
74 public synchronized void print_C () {
75 while(should_a || should_b) {
76 try {
77 this.wait();
78 } catch (InterruptedException e) {
79 // TODO Auto-generated catch block
80 e.printStackTrace();
81 }
82 }
83 System.out.print("C");
84 should_a = true;
85 should_b = false;
86 should_c = false;
87 this.notifyAll();
88 }
89 }
View Code
再一次證明了軟件工程的重要性了；在多線程程序中，應該說在程序中，我們應該把那些業務邏輯代碼放到同一個類中，使之高內聚，低耦合
