当我尝试设置任何imageview图像（setImageBitmap或setImageView）时，活动崩溃，它在任何地方但在一个getview中执行此操作。
我正在尝试获取一个imageview数组，我可以在我的适配器中使用我的gridview（问题标记为“问题在这里”）
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");
}
}
logcat的：
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
答案 0 :(得分：1)
您永远不会初始化bottomGridArray。就此而言，也不topGridArray。 （看this topic in a basic Java tutorial to see how and why you need to initialize your arrays）
行前
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];
提醒您：您的代码可能会遇到很多麻烦。您可能应该查看Google对Bitmaps in your UI的建议。