將imageview圖像導致崩潰

Question

當我嘗試設置任何imageview圖像（setImageBitmap或setImageView）時，它會在任何地方執行此操作，但只能在一個getview中執行。

我試圖得到一個imageview的陣列，我可以在我的適配器用我的GridView（問題標記爲 「問題就在這裏」）

package joshpike.hsh.hsh_game; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 

import android.annotation.SuppressLint; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Point; 
import android.os.Bundle; 
import android.view.Display; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.Window; 
import android.view.WindowManager; 
import android.widget.BaseAdapter; 
import android.widget.GridView; 
import android.widget.ImageView; 


public class DisplayActivity extends MainActivity 
{ 

    int screenTileWidth = 3; 
    int nativeTileSize = 256; 
    int tileSize; 
    int numberColumn; 
    int numberRow; 
    int floorNum; 

    ImageView[][] topGridArray = null; 
    ImageView[][] bottomGridArray = null; 

    //sets tilesize, numberColumn and numberRow 
    @SuppressLint("NewApi") 
    public void setGridVars() 
    { 
     //set tileSize 
     Display display = getWindowManager().getDefaultDisplay(); 
     Point size = new Point(); 
     int screenWidth; 

     if (android.os.Build.VERSION.SDK_INT >= 13) 
     { 
      display.getSize(size); 
      screenWidth = size.x; 
     } 
     else 
     { 
      screenWidth = display.getWidth(); 
     } 

     tileSize = screenWidth/screenTileWidth; 

     //set numberColumn and numberRow 
     try 
     { 
      String dataFilePath = "floors/" + floorNum + "/FloorData.txt"; 
      InputStream dataInputStream = getAssets().open(dataFilePath); 
      BufferedReader reader = new BufferedReader(new InputStreamReader(dataInputStream)); 

      String line = reader.readLine(); 
      line = reader.readLine(); 
      numberColumn = Integer.parseInt(line); 
      line = reader.readLine(); 
      numberRow = Integer.parseInt(line); 
      dataInputStream.close(); 
     } 
     catch (IOException e) 
     { 
      System.out.println("exception found in try/catch in DisplayActivity.setGridVars method"); 
     } 

     for(int x = 0; x < numberColumn ; x++) 
     { 
      for(int y = 0; y < numberRow ; y++) 
      { 
       ///***PROBLEM HERE***/// 
       bottomGridArray[x][y].setImageBitmap(currentImageView("bottom", x, y)); 
       topGridArray[x][y].setImageBitmap(currentImageView("top", x, y)); 
      } 
     } 




    } 

    //returns the one imageView for gridViewForadapter 
    public Bitmap currentImageView(String layer, int X, int Y) 
    { 
     try 
     { 
      Bitmap returnBitmap = null; 
      String imgDirectory = "floors/" + floorNum + "/" + layer + "/" + X + "," + Y + ".png"; 

      InputStream imageInputStream = getAssets().open(imgDirectory); 
      returnBitmap = BitmapFactory.decodeStream(imageInputStream); 
      imageInputStream.close(); 
      return returnBitmap; 

     } 
     catch (IOException e) 
     { 
      System.out.println("exception found in try/catch in DisplayActivity.currentImageView method"); 
      return null; 
     } 

    } 


    public int returnGridCord (int position, char whatCord) 
    { 
     position = position + 1; 

     float rowFromTop = (float) position/numberColumn; 

     if (rowFromTop != Math.round(rowFromTop)) 
     { 
      rowFromTop = ((float) Math.ceil(rowFromTop)); 
     } 

     int returnY = Math.abs((int)rowFromTop - numberRow); 
     int returnX = (position - (((int)rowFromTop -1) * numberColumn)) - 1; 

     System.out.println(position + ":" + returnX + "x" + returnY); 
     if (whatCord == 'X') 
     { 
      return returnX; 
     } 
     else 
     { 
      return returnY; 
     } 
    } 


    public class ImageAdapter extends BaseAdapter 
    { 

     private Context mContext; 

     // create a new ImageView for each item referenced by the Adapter 
     public View getView(int position, View convertView, ViewGroup parent) 
     { 
      ImageView imageView; 
      if (convertView == null) 
      { 
       // if it's not recycled, initialize some attributes 
       imageView = new ImageView(mContext); 
       imageView.setLayoutParams(new GridView.LayoutParams(tileSize, tileSize)); 
       imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); 
       imageView.setPadding(0, 0, 0, 0); 
      } 
      else 
      { 
       imageView = (ImageView) convertView; 
      } 




      System.out.println("endish of getview");  

      imageView.setImageResource(R.drawable.ic_launcher); 
      return imageView; 

     } 


     public ImageAdapter(Context c) 
     { 
      mContext = c; 
     } 

     @Override 
     public int getCount() 
     { 
      return numberColumn * numberRow; 
     } 

     @Override 
     public Object getItem(int position) 
     { 
      return null; 
     } 

     @Override 
     public long getItemId(int position) 
     { 
      return 0; 
     } 

    } 




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

    //what happens if you select items from the options menu 
    @Override 
    public boolean onOptionsItemSelected(MenuItem item) 
    { 
     switch (item.getItemId()) 
     { 
      case R.id.miniMap: 

      return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 

    //called when activity is started for first time either for first time or after destoryed 
    @Override 
    protected void onCreate(Bundle savedInstanceState) 
    { 
     this.requestWindowFeature(Window.FEATURE_NO_TITLE); 
     this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.display); 
     setGridVars(); 





     System.out.println("DisplayActivity test about to start");  
     //ImageAdapter test = null; 
     //returnGridCord(0,"X"); 




     GridView bottomMapGrid = (GridView)findViewById(R.id.bottomMapGrid); 
     bottomMapGrid.setNumColumns(numberColumn); 
     bottomMapGrid.setColumnWidth(tileSize); 
     bottomMapGrid.setStretchMode(GridView.NO_STRETCH) ; 
     bottomMapGrid.setAdapter(new ImageAdapter(this)); 

     System.out.println("DisplayActivity onCreate done");   
    } 



    //called when Activity goes from paused to active 
    @Override 
    protected void onResume() 
    { 
     super.onResume(); 
     System.out.println("DisplayActivity onResume done"); 
    } 

    //called when Activity goes from active to paused 
    @Override 
    protected void onPause() 
    { 
     super.onPause(); 
     System.out.println("DisplayActivity onPause done"); 

    } 

    //called when Activity goes from paused to stopped 
    @Override 
    protected void onStop() 
    { 
     super.onStop(); 
     System.out.println("DisplayActivity onStop done"); 

    } 

    //called when Activity goes from stopped to destroyed 
    @Override 
    protected void onDestroy() 
    { 
     super.onDestroy(); 
     System.out.println("DisplayActivity onDestroy done"); 

    } 

    //called when Activity has been stopped, is going to be paused then active 
    @Override 
    protected void onRestart() 
    { 
     super.onRestart(); 
     System.out.println("DisplayActivity onRestart done"); 

    } 

    //called when Activity is transitioning to paused either for first time or after it has been stopped 
    @Override 
    protected void onStart() 
    { 
     super.onStart(); 
     System.out.println("DisplayActivity onStart done"); 

    } 

} 

的logcat：

03-20 17:16:43.437: I/System.out(22850): MainActivity onCreate done 
03-20 17:16:43.437: I/System.out(22850): MainActivity onStart done 
03-20 17:16:43.437: I/System.out(22850): MainActivity onResume done 
03-20 17:16:43.848: D/TextLayoutCache(22850): Using debug level: 0 - Debug Enabled: 0 
03-20 17:16:44.088: D/libEGL(22850): loaded /system/lib/egl/libGLES_android.so 
03-20 17:16:44.168: D/libEGL(22850): loaded /system/lib/egl/libEGL_mali.so 
03-20 17:16:44.208: D/libEGL(22850): loaded /system/lib/egl/libGLESv1_CM_mali.so 
03-20 17:16:44.218: D/libEGL(22850): loaded /system/lib/egl/libGLESv2_mali.so 
03-20 17:16:44.358: D/OpenGLRenderer(22850): Enabling debug mode 0 
03-20 17:16:48.973: I/System.out(22850): MainActivity onPause done 
03-20 17:16:49.974: D/OpenGLRenderer(22850): Flushing caches (mode 0) 
03-20 17:16:50.674: I/System.out(22850): MainActivity onCreate done 
03-20 17:16:50.915: D/AndroidRuntime(22850): Shutting down VM 
03-20 17:16:50.915: W/dalvikvm(22850): threadid=1: thread exiting with uncaught exception (group=0x40aa8210) 
03-20 17:16:51.005: E/AndroidRuntime(22850): FATAL EXCEPTION: main 
03-20 17:16:51.005: E/AndroidRuntime(22850): java.lang.RuntimeException: Unable to start activity ComponentInfo{joshpike.hsh.hsh_game/joshpike.hsh.hsh_game.DisplayActivity}: java.lang.NullPointerException 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.ActivityThread.access$600(ActivityThread.java:127) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.os.Handler.dispatchMessage(Handler.java:99) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.os.Looper.loop(Looper.java:137) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.ActivityThread.main(ActivityThread.java:4448) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at java.lang.reflect.Method.invokeNative(Native Method) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at java.lang.reflect.Method.invoke(Method.java:511) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at dalvik.system.NativeStart.main(Native Method) 
03-20 17:16:51.005: E/AndroidRuntime(22850): Caused by: java.lang.NullPointerException 
03-20 17:16:51.005: E/AndroidRuntime(22850): at joshpike.hsh.hsh_game.DisplayActivity.setGridVars(DisplayActivity.java:85) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at joshpike.hsh.hsh_game.DisplayActivity.onCreate(DisplayActivity.java:235) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.Activity.performCreate(Activity.java:4465) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
03-20 17:16:51.005: E/AndroidRuntime(22850): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931) 
03-20 17:16:51.005: E/AndroidRuntime(22850): ... 11 more 
03-20 17:16:56.510: I/Process(22850): Sending signal. PID: 22850 SIG: 9 

Answer 1

你永遠不會初始化bottomGridArray 。對於這個問題，也不是topGridArray。 （請看this topic in a basic Java tutorial to see how and why you need to initialize your arrays）

你前行

for(int x = 0; x < numberColumn ; x++) 
    { 
     for(int y = 0; y < numberRow ; y++) 

插入

bottomGridArray = new ImageGrid[numberColumn][numberRow]; 
topGridArray = new ImageGrid[numberColumn][numberRow]; 

提醒你：你的代碼可能會有很多麻煩。你可能應該看看Google對Bitmaps in your UI的建議。