第一个程序
public class Test06 implements Runnable{
public int a = 0;
public static void main(String[] args) throws InterruptedException {
Test06 r = new Test06();
Thread[] t = new Thread[100];
for(int i = 0;i < 100;i++)
t[i] = new Thread(r);
for(int j = 0;j < 100;j++)
t[j].start();
Thread.currentThread().sleep(2000);
System.out.println(r.a);
}
@Override
public void run() {
int b = a+1;
try {
Thread.currentThread().sleep(10);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
a = b;
}
}
输出为？
第二个程序
public class Test06 implements Runnable{
public int a = 0;
public static void main(String[] args) throws InterruptedException {
Test06 r = new Test06();
Thread[] t = new Thread[100];
for(int i = 0;i < 100;i++)
t[i] = new Thread(r);
for(int j = 0;j < 100;j++)
t[j].start();
Thread.currentThread().sleep(2000);
System.out.println(r.a);
}
@Override
public synchronized void run() {
int b = a+1;
try {
Thread.currentThread().sleep(10);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
a = b;
}
}
输出为？
第三个程序
public class Test06 implements Runnable{
public volatile int a = 0;
public static void main(String[] args) throws InterruptedException {
Test06 r = new Test06();
Thread[] t = new Thread[100];
for(int i = 0;i < 100;i++)
t[i] = new Thread(r);
for(int j = 0;j < 100;j++)
t[j].start();
Thread.currentThread().sleep(2000);
System.out.println(r.a);
}
@Override
public void run() {
int b = a+1;
try {
Thread.currentThread().sleep(10);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
a = b;
}
}
输出为？
三个程序中只有第二个能保证输出的为100