从另一个类调用方法导致应用崩溃 [英] Calling a method from another class is causing app to crash

问题描述

我决定尝试使我的代码更加面向对象，并避免在另一个类中重复代码.

I decided to try and make my code more object oriented and avoid repetitive code in another class.

活动的源代码:

     public class EasyMode extends MainActivity {

            GameActivityPVP game = new GameActivityPVP();

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

                game.initializeButtons();
            }
        }


    public class GameActivityPVP extends MainActivity {

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

            initializeButtons();
        }

        public void initializeButtons() {

            button[0] = (Button) findViewById(R.id.button1);
        }
}

程序第二次到达我尝试使用 game.methodName(); 调用方法的那一行，程序崩溃了.没有编译错误或其他任何东西.我一般对编程都不熟悉，所以请放轻松，我尝试尽可能简化我的代码.

The second the program gets to the line where I try to call a method using game.methodName(); the program crashes. No compiling errors or anything. I am new to programming in general so please take it easy on me and I tried to simplify my code as much as possible.

Android Monitor/logcat:

W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...

和

W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView

推荐答案

您可以通过创建父类的对象来使用其他类的方法.

You can use another class's method by creating object of parent class.

请参见以下示例；

这里您要使用'GameActivityPVP'类中的方法.因此，您只需要在此类中创建一个对象.

Here you want to use method from 'GameActivityPVP' class. So you need to create one object in this class only.

  public class GameActivityPVP extends MainActivity {

        public static GameActivityPVP mGameActivity;

        public GameActivityPVP getInstance(){
             return mGameActivity; // assign value in onCreate() method.
        }

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

                mGameActivity = this; // Do not forget this, otherwise you'll get Exception here.
                initializeButtons();
            }

            public void initializeButtons() {

                button[0] = (Button) findViewById(R.id.button1);
            }
    }

现在像这样在另一个类"EasyMode"中使用此对象；

Now use this Object in another class 'EasyMode' like this;

if(GameActivityPVP.getInstance()!=null){
    GameActivityPVP.getInstance().initializeButtons();
}

这篇关于从另一个类调用方法导致应用崩溃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！