Android 使用LiveData(二)初步优化

优化一下自定义的 LiveData,官方建议用单例模式,那就用单例模式呗

前面的类是MutableLiveData 这里直接用LiveData;

public class WelcomeLiveDate extends ViewModel {
    Mylive instance = Mylive.getInstance();
    public LiveData getCurrentName(){
        return instance;
    }
    public void setNum(Card card){
        card.setNum(900);//临时更换了参数
        instance.post(card);//调用到Mylive的类的方法
    }

}

class Mylive extends LiveData {
    private static Mylive sInstance;
    public static Mylive getInstance() {
        if (sInstance == null) {
            sInstance = new Mylive();  }
        return sInstance;
    }
    private Mylive() { }

    protected void post(Card value){
       super.postValue(value);//依然还是调用super.post方法,不调用不更新
    };

}

 

自动创建一个单例模式见:https://mp.csdn.net/postedit/83060123