我从位图方法获取图像并尝试填充列表视图。但是当我在getview中调用位图函数时，会发生nullpointerException错误。请帮帮我......
这是我的观点活动类：
public class Viewactivity extends Activity{
TextView tv;
ImageView im;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.views);
ListView mListView = (ListView)findViewById(R.id.listView);
//array houlds all images
int Images[] = new int[]{
R.drawable.confidential,
...
};
//array holds all strings to be drawn in the image
CustomList adaptor = new CustomList(this , Images);
mListView.setAdapter(adaptor);
}
public Bitmap ProcessingBitmap(int image) {
// TODO Auto-generated method stub
Bitmap bm1 = null;
Bitmap newBitmap = null;
final String data =getIntent().getExtras().getString("keys");
bm1 = ((BitmapDrawable) Viewactivity.this.getResources()
.getDrawable(image)).getBitmap();
Config config = bm1.getConfig();
if(config == null){
config = Bitmap.Config.ARGB_8888;
}
newBitmap = Bitmap.createBitmap(bm1.getWidth(), bm1.getHeight(),config);
Canvas newCanvas = new Canvas(newBitmap);
newCanvas.drawBitmap(bm1, 0, 0, null);
if(data != null){
Paint paintText = new Paint(Paint.ANTI_ALIAS_FLAG);
paintText.setColor(Color.RED);
paintText.setTextSize(300);
// paintText.setTextAlign(Align.CENTER);
paintText.setStyle(Style.FILL);
paintText.setShadowLayer(10f, 10f, 10f, Color.BLACK);
Rect rectText = new Rect();
paintText.getTextBounds(data, 0, data.length(), rectText);
paintText.setTextScaleX(1.f);
newCanvas.drawText(data,
0, rectText.height(), paintText);
Toast.makeText(getApplicationContext(),
"drawText: " + data, Toast.LENGTH_LONG).show();
}else{
Toast.makeText(getApplicationContext(),
"caption empty!", Toast.LENGTH_LONG).show();
}
return newBitmap;
}
}
这是我的适配器类：
public class CustomList extends BaseAdapter{
Viewactivity act;
int[] IMAGES;
LayoutInflater inflator;
Context sContext;
//private String[] TEXTS;
public CustomList(Context context, int[] images){
this.IMAGES = images;
//this.TEXTS = texts;
this.sContext = context;
inflator = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return IMAGES.length;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v = inflator.inflate(R.layout.row_list, parent, false);
final ImageView imageView = (ImageView) v.findViewById(R.id.imageView);
imageView.setImageBitmap(act.ProcessingBitmap(IMAGES[position]));// line no:52
return imageView;
}
}
这是我的logcat：
12-18 06:16:51.406: E/AndroidRuntime(1388): FATAL EXCEPTION: main
12-18 06:16:51.406: E/AndroidRuntime(1388): Process: com.emple.example, PID: 1388
12-18 06:16:51.406: E/AndroidRuntime(1388): java.lang.NullPointerException
12-18 06:16:51.406: E/AndroidRuntime(1388): at com.emple.example.CustomList.getView(CustomList.java:52)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.AbsListView.obtainView(AbsListView.java:2263)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.ListView.onMeasure(ListView.java:1175)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.View.measure(View.java:16497)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.RelativeLayout.measureChild(RelativeLayout.java:689)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:473)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.View.measure(View.java:16497)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.View.measure(View.java:16497)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
12-18 06:16:51.406: E/AndroidRuntime(1388): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.View.measure(View.java:16497)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-18 06:16:51.406: E/AndroidRuntime(1388): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.View.measure(View.java:16497)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.Choreographer.doFrame(Choreographer.java:544)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.os.Handler.handleCallback(Handler.java:733)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.os.Handler.dispatchMessage(Handler.java:95)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.os.Looper.loop(Looper.java:136)
12-18 06:16:51.406: E/AndroidRuntime(1388): at android.app.ActivityThread.main(ActivityThread.java:5017)
12-18 06:16:51.406: E/AndroidRuntime(1388): at java.lang.reflect.Method.invokeNative(Native Method)
12-18 06:16:51.406: E/AndroidRuntime(1388): at java.lang.reflect.Method.invoke(Method.java:515)
12-18 06:16:51.406: E/AndroidRuntime(1388): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
12-18 06:16:51.406: E/AndroidRuntime(1388): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
12-18 06:16:51.406: E/AndroidRuntime(1388): at dalvik.system.NativeStart.main(Native Method)
12-18 06:21:51.616: I/Process(1388): Sending signal. PID: 1388 SIG: 9
答案 0 :(得分：2)
您尚未初始化act变量。在适配器构造函数中初始化它。
类似的东西：
public CustomList(Viewactivitty act, int[] images){
this.act = act;
this.IMAGES = images;
//this.TEXTS = texts;
this.sContext = act;
inflator = (LayoutInflater)act.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}