Android Rxjava订阅变量更改 [英] Android Rxjava subscribe to a variable change

问题描述

我正在学习观察者模式，我希望我的观察者能够在某个变量更改其值时跟踪它，并进行一些操作，我已经做了类似的事情:

I am learning Observer pattern, I want my observable to keep track of a certain variable when it changes it's value and do some operations, I've done something like :

public class Test extends MyChildActivity {

   private int VARIABLE_TO_OBSERVE = 0;

   Observable<Integer> mObservable = Observable.just(VARIABLE_TO_OBSERVE);  

   protected void onCreate() {/*onCreate method*/
       super();
       setContentView();
       method();
       changeVariable();
   }

   public void changeVariable() {
       VARIABLE_TO_OBSERVE = 1;
   }

   public void method() {
       mObservable.map(value -> {
            if (value == 1) doMethod2();
            return String.valueOf(value);
       }).subScribe(string -> System.out.println(string));
   }

   public void doMethod2() {/*Do additional operations*/}

}

但是doMethod2()没有被调用

But doMethod2() doesn't get called

推荐答案

生活中没有什么神奇的东西:如果更新值，则不会通知您的Observable.您必须自己做.例如，使用PublishSubject.

Nothing is magic in the life : if you update a value, your Observable won't be notified. You have to do it by yourself. For example using a PublishSubject.

public class Test extends MyChildActivity {

    private int VARIABLE_TO_OBSERVE = 0;

    Subject<Integer> mObservable = PublishSubject.create();  

   protected void onCreate() {/*onCreate method*/
        super();
        setContentView();
        method();
        changeVariable();
    }

    public void changeVariable() {
        VARIABLE_TO_OBSERVE = 1;
        // notify the Observable that the value just change
        mObservable.onNext(VARIABLE_TO_OBSERVE);
    }

   public void method() {
       mObservable.map(value -> {
           if (value == 1) doMethod2();
           return String.valueOf(value);
       }).subScribe(string -> System.out.println(string));
   }

   public void doMethod2() {/*Do additional operations*/}

 }

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