hi now i am trying to create folder in my gallery but my application crash in this line...how to solve these error please help me....
imagegrid.setAdapter(new ImAdapterh(getApplicationContext()));
System.out.println("index"+getApplicationContext());
code:
public class ImAdapterh extends BaseAdapter{
File dir=new File(Environment.getExternalStorageDirectory(),"/Pictures/");
int count=dir.list().length;
String[] fileNames = dir.list();
private Context mContext;
public ImAdapterh(Context c) {
mContext = c;
}
public int getCount() {
return count;
}
public Object getItem(int position) {
开发者_开发问答 return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView = null;
for(String bitmapFileName : fileNames)
{
if (convertView == null)
{ // if it's not recycled, initialize some attributes
imageView = new ImageView(mContext);
imageView.setLayoutParams(new Gallery.LayoutParams(85, 85));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8, 8, 8, 8);
Bitmap bmp = BitmapFactory.decodeFile(dir.getPath() + "/" +
bitmapFileName);
System.out.println(dir);
imageView.setImageBitmap(bmp);
}else
{
imageView = (ImageView) convertView;
}
}
return imageView;
}
}}
logcat error:
05-03 22:37:50.134: DEBUG/AndroidRuntime(1328): Shutting down VM
05-03 22:37:50.134: WARN/dalvikvm(1328): threadid=1: thread exiting with uncaught
exception (group=0x4001d800)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): FATAL EXCEPTION: main
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): java.lang.RuntimeException: Unable to
start activity
ComponentInfo{ImageViewExample.ImageViewExample/ImageViewExample
.ImageViewExample.ImageViewExample}: java.lang.NullPointerException
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.ActivityThread.access$2300(ActivityThread.java:125)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.os.Handler.dispatchMessage(Handler.java:99)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.os.Looper.loop(Looper.java:123)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.ActivityThread.main(ActivityThread.java:4627)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
java.lang.reflect.Method.invokeNative(Native Method)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
java.lang.reflect.Method.invoke(Method.java:521)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
dalvik.system.NativeStart.main(Native Method)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): Caused by:
java.lang.NullPointerException
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
ImageViewExample.ImageViewExample.ImageViewExample$ImAdapterh.<init>
(ImageViewExample.java:72)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
ImageViewExample.ImageViewExample.ImageViewExample
.init_phone_image_grid(ImageViewExample.java:49)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
ImageViewExample.ImageViewExample.ImageViewExample
.onCreate(ImageViewExample.java:36)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
05-03 22:37:50.184: ERROR/AndroidRuntime(1328): ... 11 more
I don't think I really understand the question... However, you're getting a null pointer exception.
This looks wrong to me:
public Object getItem(int position)
{
return null;
}
However, it's the same as this example so I'm sure it is fine.
If you application is crashing at this line (which you've said):
imagegrid.setAdapter(new ImAdapterh(getApplicationContext()));
Then is seems like, either there must be a null on that line, or a side effect of one of the calls causes the exception.
So, obvious possibilities:
- Is
imagegrid
null at this point? If so, invoking a method on it will cause a null exception. You've presumably created and initialized it somewhere, but you don't include that code. - Does
getApplicationContext
return non-null? It's assigned within the constructor forImAdapterh
, but not used by the constructor, but it's worth checking.
Your ImAdapterh
contains the following lines:
File dir=new File(Environment.getExternalStorageDirectory(),"/Pictures/");
int count=dir.list().length;
String[] fileNames = dir.list();
This seems error prone to me, although it may be stylistic... I'd try changing it to:
File dir;
int count;
String[] fileNames;
Then construct the objects in your constructor for the class. This may also give you a better stack trace if one of these lines is causing the problem (and allows you to set a breakpoint on the constructor code).
I'd also set a breakpoint at the start of your getView
method, to see if it is being called as a result of your setting the adapter for the imagegrid
.
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