You only need to copy and paste
单例：保证一个类仅有一个实例，并提供一个访问它的全局访问点
直接看代码最终实现：
public class SingletonTest {
private static SingletonTest instance = null;
private SingletonTest() {
}
private static synchronized void syncInit() {
if (instance == null) {
instance = new SingletonTest();
}
}
public static SingletonTest getInstance() {
if (instance == null) {
syncInit();
}
return instance;
}
}
补充：采用"影子实例"的办法为单例对象的属性同步更新
public class SingletonTest {
private static SingletonTest instance = null;
private Vector properties = null;
public Vector getProperties() {
return properties;
}
private SingletonTest() {
}
private static synchronized void syncInit() {
if (instance == null) {
instance = new SingletonTest();
}
}
public static SingletonTest getInstance() {
if (instance == null) {
syncInit();
}
return instance;
}
public void updateProperties() {
SingletonTest shadow = new SingletonTest();
properties = shadow.getProperties();
}
}
