关于使用Thread.yield()进行线程通讯的问题
//代码1
package communication;
import java.util.Random;
public class Flag {
public static void main(String[] args) {
FlagSender f = new FlagSender();
FlagRec r = new FlagRec(f);
Thread t1 = new Thread(f);
Thread t2 = new Thread(r);
t1.start();
t2.start();
}
}
class FlagSender implements Runnable{
private int theValue;
private boolean flag;
public int getTheValue() {
return theValue;
}
public void setTheValue(int theValue) {
this.theValue = theValue;
}
public boolean isFlag() {
return flag;
}
public void setFlag(boolean flag) {
this.flag = flag;
}
@Override
public void run() {
for (int i = 0; i < 5; i++) {
while(flag){
Thread.yield();
}
theValue = new Random().nextInt(1000);
System.out.println("send the value is "+theValue);
flag = true;
}
}
}
class FlagRec implements Runnable{
private FlagSender f;
public FlagRec(FlagSender f) {
super();
this.f = f;
}
@Override
public void run() {
for (int i = 0; i < 5; i++) {
while(!f.isFlag()){
Thread.yield();
}
System.out.println("receive the value is "+f.getTheValue());
f.setFlag(false);
}
}
}//代码2
package communication;
import java.util.Random;
public class WrongOfFlag {
public static void main(String[] args) {
FlagSender1 f = new FlagSender1();
FlagRec1 r = new FlagRec1();
Thread t1 = new Thread(f);
Thread t2 = new Thread(r);
t1.start();
t2.start();
}
}
class FlagSender1 implements Runnable{
private int theValue;
private boolean flag;
public int getTheValue() {
return theValue;
}
public void setTheValue(int theValue) {
this.theValue = theValue;
}
public boolean isFlag() {
return flag;
}
public void setFlag(boolean flag) {
this.flag = flag;
}
@Override
public void run() {
for (int i = 0; i < 5; i++) {
while(flag){
Thread.yield();
}
theValue = new Random().nextInt(1000);
System.out.println("send the value is "+theValue);
flag = true;
}
}
}
class FlagRec1 implements Runnable{
FlagSender f = new FlagSender();
@Override
public void run() {
for (int i = 0; i < 5; i++) {
while(!f.isFlag()){
Thread.yield();
}
System.out.println("receive the value is "+f.getTheValue());
f.setFlag(false);
}
}
}为什么要让FlagSender作为FlagRec的成员，像代码二中直接new了FlagSender为什么结果只输出一个send the value is 138，然后就死循环空程序了，结果如下图
