Question

代码：

        package com.example.theball;
import java.util.Timer;
import java.util.TimerTask;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.content.pm.ActivityInfo;
import android.graphics.Canvas;
import android.graphics.Point;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.view.Display;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
@SuppressLint("NewApi") public class MainActivity extends Activity implements SensorEventListener {
        private SensorManager sensorManager;
        private Sensor accelerometer;
        @SuppressWarnings("unused")
        private long lastUpdate;
        AnimatedView animatedView = null;
        ShapeDrawable mDrawable = new ShapeDrawable();
        public static int x;
        public static int y;
        public static final int width = 50;
        public static final int height = 50;
        public boolean firstDraw = true;
        private int screen_width; 
        private int screen_height; 
        private int sensorX;
        private Timer t;
        private int TimeCounter = 0;
        private int sensorY;
        private int score = 0;
        @Override        
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
            sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
            accelerometer = sensorManager
                    .getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
            lastUpdate = System.currentTimeMillis();
            animatedView = new AnimatedView(this);
            setContentView(animatedView);
            t=new Timer();
            t.scheduleAtFixedRate(new TimerTask() {
                public void run() {
                    runOnUiThread(new Runnable() {
                        public void run() {                 
                            TimeCounter++;      
                        }
                       });
                    }
            }, 0, 1000); 
        }
            public static class MainActivity extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
          View v = inflater.inflate(R.layout.activity_main, container, false);
          TextView highscore_int = (TextView)v.findViewById(R.id.highscore_int );
           SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", 
            Context.MODE_PRIVATE);
           score = prefs.getInt("key", 0);
          highscore_int.setText("Highscore:" + score +" seconds."); 
          return v;
    }
        @Override
        protected void onResume() {

            super.onResume();
            sensorManager.registerListener(this, accelerometer,
                    SensorManager.SENSOR_DELAY_GAME);
        }
        @Override
        protected void onPause() {
            super.onPause();
            sensorManager.unregisterListener(this);
        }
        @Override
        public void onAccuracyChanged(Sensor arg0, int arg1) {
            // TODO Auto-generated method stub
        }
        @Override
        public void onSensorChanged(SensorEvent event) {
            // TODO Auto-generated method stub
            if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
                sensorY = (int) event.values[1];
                sensorX = (int) event.values[0];
                x -= sensorX*3;
                y += sensorY*3;
                if(x <= 0 || x >= screen_width || y <= 0 || y >= screen_height) { 
                    SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
                     int oldScore = prefs.getInt("key", 0);  
                     if( TimeCounter > oldScore ){
                        Editor edit = prefs.edit();
                        edit.putInt("key", TimeCounter);
                        edit.commit(); }
                    Intent myIntent = new Intent(this, YouLost.class);
                    startActivity(myIntent);
            }
        }
        }
        public class AnimatedView extends ImageView { 

            Display display = getWindowManager().getDefaultDisplay(); 
            Point size = new Point(); 
            static final int width = 50; 
            static final int height = 50; 
            @SuppressLint("NewApi") 
            public AnimatedView(Context context) { 
            super(context); 
            // TODO Auto-generated constructor stub 
            display.getSize(size); 
            screen_width = size.x; 
            screen_height = size.y; 
            mDrawable = new ShapeDrawable(new OvalShape()); 
            mDrawable.getPaint().setColor(0xffffAC23); 
            mDrawable.setBounds(0, 0, screen_width, screen_height); 
            }
            @Override 
            protected void onDraw(Canvas canvas) { 
            mDrawable.setBounds(x, y, x + width, y + height); 
            if(firstDraw) { 
            x = screen_width / 2; 
            y = screen_height / 2; 
            firstDraw = false; 
            } 
            mDrawable.draw(canvas); 
            invalidate(); 
            } 
            }
}

我的新问题是，在Eclipse Graphical Layout中我可以看到文本，但在我的设备上我不能。

我不知道为什么会发生这种情况，无论如何，我的文字设置为黑色，背景是白色的，所以这不是问题。

Answer 1

textview highscore_int为空，因为您从highscore_int引用fragment_main.xml，您将获得null，因为在您的活动中，您使用activity's layout

因此，在片段的highscore_int中使用onCreateView会使视图膨胀

View v = inflater.inflate(R.layout.fragment_main, container, false);

然后使用视图查找textview

TextView highscore_int = (TextView)v.findViewById(R.id.highscore_int );

即。

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
          View v = inflater.inflate(R.layout.fragment_main, container, false);
          TextView highscore_int = (TextView)v.findViewById(R.id.highscore_int );
           SharedPreferences prefs = getActivity().getSharedPreferences("myPrefsKey", 
            Context.MODE_PRIVATE);
           score = prefs.getInt("key", 0);
          highscore_int.setText("Highscore:" + score +" seconds."); 
          return v;
    }

Answer 2

我的猜测基于fragment_main.xml这个词。我猜您粘贴的代码来自您的活动，布局基于您的片段。这意味着您只能在片段类中调用findViewById()。

覆盖片段方法onCreateView()并在那里获得高分TextView。也可以在那里移动代码：

//onCreateView() of your fragment
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_main, null);
    highscore_int = (TextView) view.findViewById(R.id.highscore_int);

    SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
    score = prefs.getInt("key", 0);
    highscore_int.setText("Highscore:" + score +" seconds.");

    // You lost
    SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
    int oldScore = prefs.getInt("key", 0);  
    if( TimeCounter > oldScore ) {
        Editor edit = prefs.edit();
        edit.putInt("key", TimeCounter);
        edit.commit();
    }
}

Answer 3

因为prefs.getInt("key", 0);返回null并存储在得分

中

使用此

score = 0;
if(prefs.getInt("key", 0) != null){
   score = prefs.getInt("key", 0);
}

应用程序崩溃..用logcat找到解释但不知道为什么

3 个答案: