我有一个listview，它可以调整水平进度条对话框。进度条出现，但是没有加载请帮助我。我也得到空指针异常。
这是我为listview设置适配器的主要活动
public class ListProgress extends ActionBarActivity {
ListView lvProgress;
public ProgressBarAdapter progressBarAdapter;
public int pStatus;
public ProgressBar progressBar;
public Handler handler = new Handler();
int budgetVal=600;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list_progress);
lvProgress =(ListView) findViewById(R.id.lvProgress);
progressBar =(ProgressBar) findViewById(R.id.progressBar1);
progressBarAdapter = new ProgressBarAdapter(this);
lvProgress.setAdapter(progressBarAdapter);
}
这是扩展基本适配器的类。进度对话框显示正常，但根本无法加载。
public class ProgressBarAdapter extends BaseAdapter{
TextView tv;
private Handler handler = new Handler();
public ViewHolder holder;
private Context ctx;
final class ViewHolder {
public ProgressBar pBar;
}
public ProgressBarAdapter(Context ctx) {
this.ctx = ctx;
}
@Override
public int getCount() {
return 1;
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
holder = new ViewHolder();
LayoutInflater inflater= (LayoutInflater) ctx.getSystemService(Context
.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.activity_progress_dialog_demo, null);
holder.pBar = (ProgressBar) convertView.findViewById(R.id.progressBar1);
new myTask().execute();
// Thread t = new Thread(new Runnable() {
// int budgetVal = 600;
// int pStatus=0;
// @Override
// public void run() {
// // TODO Auto-generated method stub
// while (pStatus <= budgetVal) {
//
// handler.post(new Runnable() {
//
// @Override
// public void run() {
// // TODO Auto-generated method stub
// holder.pBar.setProgress(pStatus);
// holder.pBar.setSecondaryProgress(pStatus + 5000);
// // Toast.makeText(ctx,"Touched: " + pStatus ,Toast.LENGTH_LONG).show();
// }
// });
// try {
// // Sleep for 200 milliseconds.
// // Just to display the progress slowly
// Thread.sleep(50);
// } catch (InterruptedException e) {
// e.printStackTrace();
// }
// pStatus++;
// }
// }
// });t.start();
return convertView;
}
class myTask extends AsyncTask<Void, Void, Void>
{
int pStatus=0;
@Override
protected void onPreExecute() {
super.onPreExecute();
holder.pBar .setMax(1200);
holder.pBar .setProgress(pStatus);
holder.pBar .setVisibility(View.VISIBLE);
pStatus=0;
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
pStatus++;
holder.pBar .setProgress(pStatus);
}
@Override
protected Void doInBackground(Void... params) {
return null;
}
}
}
LogCat上的空指针异常
06-16 17:54:14.382 16120-16120/? E/dalvikvm﹕ >>>>> Normal User
06-16 17:54:14.382 16120-16120/? E/dalvikvm﹕ >>>>> com.example.fritzmichaelquaye.datedemo [ userId:0 | appId:10251 ]
06-16 17:54:14.712 16120-16120/com.example.fritzmichaelquaye.datedemo E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.fritzmichaelquaye.datedemo, PID: 16120
java.lang.NullPointerException
at com.example.fritzmichaelquaye.adapter.ProgressBarAdapter$myTask.onPreExecute(ProgressBarAdapter.java:125)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
at android.os.AsyncTask.execute(AsyncTask.java:535)
at com.example.fritzmichaelquaye.adapter.ProgressBarAdapter.getView(ProgressBarAdapter.java:73)
at android.widget.AbsListView.obtainView(AbsListView.java:2765)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1274)
at android.widget.ListView.onMeasure(ListView.java:1186)
at android.view.View.measure(View.java:17478)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5364)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1410)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:17478)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5364)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:17478)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5364)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
at android.view.View.measure(View.java:17478)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5364)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:17478)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5364)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1410)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:17478)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5364)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2548)
at android.view.View.measure(View.java:17478)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2259)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1388)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1587)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1246)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6567)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:803)
at android.view.Choreographer.doCallbacks(Choreographer.java:603)
at android.view.Choreographer.doFrame(Choreographer.java:573)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:789)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5476)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
at dalvik.system.NativeStart.main(Native Method)