public class thread1 extends Thread {
public void run() {
while (true) {
synchronized (test.i) {
int i = test.i;
System.out.println(i);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
public class thread2 extends Thread {
public void run() {
while (true) {
synchronized (test.i) {
int i = test.i;
i++;
test.i = i;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
public class test { public static int i = 0; public static void main(String[] args) {
thread1 t1 = new thread1();
thread2 t2 = new thread2();
t1.start();
t2.start();
}
}
这样写会报错,为什么,应该怎么改
public void run() {
while (true) {
synchronized (test.i) {
int i = test.i;
System.out.println(i);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
public class thread2 extends Thread {
public void run() {
while (true) {
synchronized (test.i) {
int i = test.i;
i++;
test.i = i;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
public class test { public static int i = 0; public static void main(String[] args) {
thread1 t1 = new thread1();
thread2 t2 = new thread2();
t1.start();
t2.start();
}
}
这样写会报错,为什么,应该怎么改
int i = 0;
Integer i = 0;有什么区别吗
因为基本数据类型有时候在我们操作对象的时候不方便,于是就出现了包装类,就像你举的这个例子。
synchronized括号里面,只能是对象,int i =0 这个i只是一个基本数据类型,我们为了使用i,那就必须让他变成对象,就必须用Integer i = 0;