java多线程同步生产者消费者问题

Posted 2020-09-08 xiongjiawei

 1 package 多线程;
 2 class Producer implements Runnable{
 3     private Data data;
 4     public Producer(Data data){
 5         this.data=data;
 6     }
 7     @Override
 8     public synchronized void run() {
 9         for(int i=0;i<50;i++){
10             if(i%2==0){
11                 this.data.setTitle("饼干");
12                 try {
13                     Thread.sleep(100);
14                 } catch (InterruptedException e) {
15                     e.printStackTrace();
16                 }
17                 this.data.setValue("麦香饼干");
18             }else{
19                 this.data.setTitle("饮料");
20                 try {
21                     Thread.sleep(100);
22                 } catch (InterruptedException e) {
23                     e.printStackTrace();
24                 }
25                 this.data.setValue("果汁好喝");
26             }
27         }
28     }
29 }
30 class Consumer implements Runnable{
31     private Data data;
32     public Consumer(Data data){
33         this.data=data;
34     }
35     @Override
36     public synchronized void run() {
37         for(int i=0;i<50;i++){
38             try {
39                 Thread.sleep(100);
40             } catch (InterruptedException e) {
41                 e.printStackTrace();
42             }
43             System.out.println("消费："+this.data.getTitle()+"->"+this.data.getValue());
44         }
45     }
46 }
47 class Data{
48     private String title;
49     private String value;
50     public void setTitle(String title) {
51         this.title = title;
52     }
53     public String getTitle() {
54         return title;
55     }
56     public void setValue(String value) {
57         this.value = value;
58     }
59     public String getValue() {
60         return value;
61     }
62 }
63 public class TestProducerConsumer {
64     public static void main(String[] args) {
65         Data data=new Data();
66         new Thread(new Producer(data)).start();
67         new Thread(new Consumer(data)).start();
68     }
69 }

数据错乱

 

 1 package 多线程;
 2 class Producer implements Runnable{
 3     private Data data;
 4     public Producer(Data data){
 5         this.data=data;
 6     }
 7     @Override
 8     public void run() {
 9         for(int i=0;i<50;i++){
10             if(i%2==0){
11                 this.data.set("饼干","麦香饼干");                
12             }else{
13                 this.data.set("饮料","果汁好喝");
14             }
15         }
16     }
17 }
18 class Consumer implements Runnable{
19     private Data data;
20     public Consumer(Data data){
21         this.data=data;
22     }
23     @Override
24     public void run() {
25         for(int i=0;i<50;i++){
26             System.out.println("消费："+this.data.get());
27         }
28     }
29 }
30 class Data{
31     private String title;
32     private String value;
33     public synchronized void set(String title,String value) {
34         //若不加synchronized仍会有数据错乱现象
35         this.title = title;
36         try {
37             Thread.sleep(100);
38         } catch (InterruptedException e) {
39             e.printStackTrace();
40         }
41         this.value=value;
42     }
43     public synchronized String get() {
44         try {
45             Thread.sleep(100);
46         } catch (InterruptedException e) {
47             e.printStackTrace();
48         }
49         return title+"->"+value;
50     }
51 }
52 public class TestProducerConsumer {
53     public static void main(String[] args) {
54         Data data=new Data();
55         new Thread(new Producer(data)).start();
56         new Thread(new Consumer(data)).start();
57     }
58 }

解决错乱，但有重复现象（非奇偶交替）

 

 1 package 多线程;
 2 class Producer implements Runnable{
 3     private Data data;
 4     public Producer(Data data){
 5         this.data=data;
 6     }
 7     @Override
 8     public void run() {
 9         for(int i=0;i<50;i++){
10             if(i%2==0){
11                 this.data.set("饼干","麦香饼干");                
12             }else{
13                 this.data.set("饮料","果汁好喝");
14             }
15         }
16     }
17 }
18 class Consumer implements Runnable{
19     private Data data;
20     public Consumer(Data data){
21         this.data=data;
22     }
23     @Override
24     public void run() {
25         for(int i=0;i<50;i++){
26             System.out.println("消费："+this.data.get());
27         }
28     }
29 }
30 class Data{
31     private boolean flag=true;//如果不初始设置为true可能会在第一个消费时取得null
32     private String title;
33     private String value;
34     public synchronized void set(String title,String value) {
35         if(this.flag==false)
36             try {
37                 super.wait();
38             } catch (InterruptedException e1) {
39                 e1.printStackTrace();
40             }
41         //若不加synchronized仍会有数据错乱现象
42         this.title = title;
43         try {
44             Thread.sleep(100);
45         } catch (InterruptedException e) {
46             e.printStackTrace();
47         }
48         this.value=value;
49         this.flag=false;
50         super.notify();
51     }
52     public synchronized String get() {
53         if(this.flag==true)
54             try {
55                 super.wait();
56             } catch (InterruptedException e1) {
57                 e1.printStackTrace();
58             }
59         try {
60             Thread.sleep(100);
61         } catch (InterruptedException e) {
62             e.printStackTrace();
63         }
64         this.flag=true;
65         super.notify();
66         return title+"->"+value;
67     }
68 }
69 public class TestProducerConsumer {
70     public static void main(String[] args) {
71         Data data=new Data();
72         new Thread(new Producer(data)).start();
73         new Thread(new Consumer(data)).start();
74     }
75 }

解决重复问题