android单例模式怎么实现

在Android中，可以通过以下几种方式实现单例模式：

public class Singleton {private static Singleton instance;private Singleton() {}public static synchronized Singleton getInstance() {if (instance == null) {instance = new Singleton();}return instance;}}

public class Singleton {private static final Singleton instance = new Singleton();private Singleton() {}public static Singleton getInstance() {return instance;}}

public class Singleton {private volatile static Singleton instance;private Singleton() {}public static Singleton getInstance() {if (instance == null) {synchronized (Singleton.class) {if (instance == null) {instance = new Singleton();}}}return instance;}}

public class Singleton {private static class SingletonHolder {private static final Singleton INSTANCE = new Singleton();}private Singleton() {}public static Singleton getInstance() {return SingletonHolder.INSTANCE;}}

以上是几种常见的Android中实现单例模式的方式，具体选择哪种方式取决于实际需求和性能要求。