内存泄露情况

1.单例，成员变量有Context(如果这个Context是Activity的话就会内存泄露了)，因为instance是静态的，持有context的引用

public class Singleton{
    public static Singleton instance;
    public Context context;
    public static Singleton getInstance(Context context){
        if(instance == null){
            instance = new Singleton();
        }        
        instance.context = context;//正确的是这里context.getApplicationContext();
        return instance;
    }
}