- 懶漢模式
public class Singleton {
private Singleton() {
}
private volatile static Singleton mInstance;// 第一層鎖：保證變量可見性
public static Singleton getInstance() {
if (mInstance == null) {
synchronized (Singleton.class) {
if (mInstance == null) {
mInstance = new Singleton();
}
}
}
return mInstance;
}
}
- 惡漢模式
class Singleton {
private static final Singleton ourInstance = new Singleton();
static Singleton getInstance() {
return ourInstance;
}
private Singleton() {
}
}
- 靜態(tài)內(nèi)部類模式
public class Singleton {
// 私有構(gòu)造函數(shù)
private Singleton() {
}
public static Singleton getInstance() {
return SingletonHolder.instance;
}
private static class SingletonHolder {
private static final Singleton instance = new Singleton();
}
}
其中用的最多也是最常用的是第3種，靜態(tài)內(nèi)部類單例。
