单例实现-记录
2020-11-16 本文已影响0人
咸鱼小笼包
第一种：
public class InstanceA {
private static InstanceAinstanceA;
private InstanceA() {
}
public static InstanceA getInstance() {
if (instanceA ==null) {
synchronized (InstanceA.class){
if (instanceA ==null){
instanceA =new InstanceA();
}
}
}
return instanceA;
}
}
第二种：
public class InstanceA {
private InstanceA() {
}
private static class TestHolder {
private static InstanceAinstanceA =new InstanceA();
}
public static InstanceA getInstance() {
return TestHolder.instanceA;
}
}
