Question

我一直在阅读Observer模式以保持我的UI最新，但我仍然无法让它工作，据我所知，Observer是我的UI，它监视我的Pet类的任何变量更改是否有任何运行update（）;它什么都不做，甚至没有Log.d。

观测/ MainActivity

package com.grim.droidchi;

import java.util.Observable;
import java.util.Observer;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebSettings.LayoutAlgorithm;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements Observer, OnClickListener {
    private static final String TAG = "VPET";
    private static final String APP_PREFS = "VPET";
    private static final int REQUEST_CODE = 1;

    TextView happiness_display, health_display, hunger_display, level_display;
    Button PunchPet, UpdateHunger;
    public static Pet pet = new Renamon();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        WebView myWebView = (WebView) findViewById(R.id.pet_display);
        myWebView.loadUrl("file:///android_asset/renamon.gif");
        myWebView.setInitialScale(10000);
        myWebView.getSettings().setLayoutAlgorithm(LayoutAlgorithm.SINGLE_COLUMN);


        PunchPet = (Button) findViewById(R.id.PunchPet);
        UpdateHunger = (Button) findViewById(R.id.UpdateHunger);
        final TextView hunger_display = (TextView) findViewById(R.id.hunger_display);
        TextView happiness_display = (TextView) findViewById(R.id.happiness_display);
        TextView level_display = (TextView) findViewById(R.id.level_display);
        TextView health_display = (TextView) findViewById(R.id.health_display);

        hunger_display.setText(Integer.toString(pet.getHunger()));
        health_display.setText(Integer.toString(pet.getHP()));
        level_display.setText(Integer.toString(pet.getLVL()));
        happiness_display.setText(Integer.toString(pet.getHappy()));


        Intent intent = new Intent(this, Gameloop.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(
                getBaseContext(), REQUEST_CODE, intent, 0);

        AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,
                System.currentTimeMillis() + (5 * 1000), 1800000, pendingIntent);
        // 1800000 ms = 30 mins

        pet.feed();
        pet.addObserver(this);
        pet.notifyObservers(pet);


    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    @Override
    protected void onPause() {


        super.onPause();
    }

    @Override
    public void update(Observable o, Object data) {
        Toast.makeText(getApplicationContext(), "soemthing has changed", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onClick(View v) {
        if (v == PunchPet) {
            pet.setLVL(50);
            pet.notifyObservers(pet);
            Log.d(TAG, "PUNCHPET" + pet.getHP());

    }else {

    }



    }

}

可观测/宠物

package com.grim.droidchi;

import java.util.Observable;


import android.util.Log;

public class Pet extends Observable implements PetInterface {

    private static final String TAG = "VPET";
    private int Health = 100;

    private int Happiness = 10;
    private int Level = 1;
    private int Hunger = 0;
    private int Exp = 0;
    private String Name;
    private Boolean isAlive = true;
    private Boolean isSick = false;

    public void setisAlive(boolean answer) {
        this.isAlive = answer;
    }

    public void setisSick(boolean answer) {
        this.isAlive = answer;
    }

    public void setHP(int hp) {
        this.Health = hp;
        notifyObservers(hp);
    }

    public void setLVL(int lvl) {
        this.Level = lvl;
        notifyObservers(lvl);
    }

    public void setXP(int xp) {
        this.Exp = xp;
        notifyObservers(xp);
    }

    public void setHunger(int hunger) {
        this.Hunger = hunger;
        notifyObservers(hunger);
    }

    public void setHappy(int happy) {
        this.Happiness = happy;
        notifyObservers(happy);
    }

    public int getHP() {

        return Health;
    }

    public int getLVL() {

        return Level;
    }

    public int getXP() {

        return Exp;
    }

    public int getHunger() {

        return Hunger;
    }

    public int getHappy() {

        return Happiness;
    }

    public boolean isAlive() {
        return isAlive;

    }

    public boolean isSick() {
        return isSick;

    }

    @Override
    public void sleep() {
        // TODO Auto-generated method stub

    }

    @Override
    public void clean() {
        // TODO Auto-generated method stub

    }

    @Override
    public void feed() {
        Log.d(TAG, "FEEDING FROM INTERFACE THING");

    }

    @Override
    public void passtime() {

    }

}

是的我也问过这个，但是你知道，它有两个答案（虽然它们可能是对的但是没有帮助我）并且现在不会再收到它了，它会在列表中掉得太远，如果我可以删除它，我会

logcat的

02-25 22:51:50.381: E/AndroidRuntime(12026): FATAL EXCEPTION: main
02-25 22:51:50.381: E/AndroidRuntime(12026): java.lang.NullPointerException
02-25 22:51:50.381: E/AndroidRuntime(12026):    at com.grim.droidchi.MainActivity.update(MainActivity.java:93)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at java.util.Observable.notifyObservers(Observable.java:138)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at com.grim.droidchi.Pet.setHP(Pet.java:33)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at com.grim.droidchi.MainActivity$1.onClick(MainActivity.java:47)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at android.view.View.performClick(View.java:4202)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at android.view.View$PerformClick.run(View.java:17340)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at android.os.Handler.handleCallback(Handler.java:725)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at android.os.Handler.dispatchMessage(Handler.java:92)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at android.os.Looper.loop(Looper.java:137)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at android.app.ActivityThread.main(ActivityThread.java:5191)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at java.lang.reflect.Method.invokeNative(Native Method)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at java.lang.reflect.Method.invoke(Method.java:511)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
02-25 22:51:50.381: E/AndroidRuntime(12026):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

问题是您已覆盖notifyObservers()，但未覆盖notifyObservers(java.lang.Object)。你正在调用后者，但你没有定义它。

    @Override
    public void notifyObservers(Object o) {
        observers.notify(o);
        super.notifyObservers(o);
    }

此外，您在内部可能会更改值，但观察者不知道。在你的“宠物”（Observable）上调用setChanged()来解决这个问题。

Answer 2

当您从Observable继承时，您的类会继承其所有功能。除非您添加自己的功能，否则无需覆盖其方法或保留自己的Observers集。正如Bailey S所述，在您的setter方法中，在致电notifyOservers()之前，请致电setChanged()。

尝试从Observable类中删除您已覆盖的所有方法。此外，每次拨打notifyObservers(object)时，请稍后致电clearChanged()。

Answer 3

问题是除非之前调用notifyObservers()，否则setChanged()方法不会执行任何操作。这不直观，因为它似乎总是应该通知观察者，但事实并非如此。不需要使用clearChagned()方法，因为notifyObervers()也会清除更改的标志。在getter和setter中使用这样的代码：

public void setHP(int hp) {
    this.Health = hp;
    setChanged();
    notifyObservers(hp);
}

另外，不要覆盖Observable中的方法，只需要实现接口`Observer中的方法。

您的update()方法需要做一些事情。这是一些非常简单的示例代码。在其中，Observable对象和数据被忽略，因为您已经知道它是什么对象，我们只是更新所有字段。

@Override
public void update(Observable o, Object data) {
    Toast.makeText(getApplicationContext(), "soemthing has changed",Toast.LENGTH_LONG).show();

    //Update the GUI fields with values from the local pet object.
    hunger_display.setText(Integer.toString(pet.getHunger()));
    health_display.setText(Integer.toString(pet.getHP()));
    level_display.setText(Integer.toString(pet.getLVL()));
    happiness_display.setText(Integer.toString(pet.getHappy()));

}

在onCreate()中，您需要正确初始化实例变量。

onCreate() {
    ...

    hunger_display = (TextView) findViewById(R.id.hunger_display);
    happiness_display = (TextView) findViewById(R.id.happiness_display);
    level_display = (TextView) findViewById(R.id.level_display);
    health_display = (TextView) findViewById(R.id.health_display);

    ...
}

换句话说，您需要删除TextView声明，因为它们正在创建新变量，而不是设置您实际想要设置的变量。

Observer Observables实施问题

3 个答案: