我不明白为什么它会回复给我这个错误，请帮帮我！ :( 这是错误：
10-31 15:33:28.595: E/Trace(7356): error opening trace file: No such file or directory (2)
10-31 15:33:29.125: E/AndroidRuntime(7356): FATAL EXCEPTION: main
10-31 15:33:29.125: E/AndroidRuntime(7356): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.appuniradiocesena/com.example.appuniradiocesena.SwipeyTabsSampleActivity}: java.lang.NullPointerException
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.ActivityThread.access$600(ActivityThread.java:140)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.os.Handler.dispatchMessage(Handler.java:99)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.os.Looper.loop(Looper.java:137)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.ActivityThread.main(ActivityThread.java:4898)
10-31 15:33:29.125: E/AndroidRuntime(7356): at java.lang.reflect.Method.invokeNative(Native Method)
10-31 15:33:29.125: E/AndroidRuntime(7356): at java.lang.reflect.Method.invoke(Method.java:511)
10-31 15:33:29.125: E/AndroidRuntime(7356): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
10-31 15:33:29.125: E/AndroidRuntime(7356): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
10-31 15:33:29.125: E/AndroidRuntime(7356): at dalvik.system.NativeStart.main(Native Method)
10-31 15:33:29.125: E/AndroidRuntime(7356): Caused by: java.lang.NullPointerException
10-31 15:33:29.125: E/AndroidRuntime(7356): at com.example.appuniradiocesena.SwipeyTabsSampleActivity.onCreate(SwipeyTabsSampleActivity.java:77)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.Activity.performCreate(Activity.java:5184)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1083)
10-31 15:33:29.125: E/AndroidRuntime(7356): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064)
10-31 15:33:29.125: E/AndroidRuntime(7356): ... 11 more
这是我跑的第一堂课：
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;
import java.util.TimerTask;
import net.moraleboost.streamscraper.ScrapeException;
import net.moraleboost.streamscraper.Scraper;
import net.moraleboost.streamscraper.Stream;
import net.moraleboost.streamscraper.scraper.IceCastScraper;
import android.annotation.TargetApi;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MenuItem.OnMenuItemClickListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
public class SwipeyTabsSampleActivity extends FragmentActivity {
private Button streamButton;
private ImageButton playButton;
private TextView textStreamed;
private TextView textSong;
private boolean isPlaying;
private StreamingMediaPlayer audioStreamer;
private SwipeyTabs mTabs;
private ViewPager mViewPager;
private static final String [] TITLES = {
"Live Stream",
"Palinsesto",
"Programmi",
"Eventi",
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_swipeytab);
mViewPager = (ViewPager) findViewById(R.id.viewpager);
mTabs = (SwipeyTabs) findViewById(R.id.swipey_tab);
SwipeyTabsPagerAdapter adapter = new SwipeyTabsPagerAdapter(this,
getSupportFragmentManager());
mViewPager.setAdapter(adapter);
mTabs.setAdapter(adapter);
mViewPager.setOnPageChangeListener(mTabs);
mViewPager.setCurrentItem(0);
/*
Inizializza();
//new AsyncTaskProc().execute();
//new Timer().schedule(new IceCastPoll(), 1000);
*/
}
private void startStreamingAudio() {
try {
final ProgressBar progressBar = (ProgressBar) findViewById(R.id.progress_bar);
if ( audioStreamer != null) {
audioStreamer.interrupt();
}
audioStreamer = new StreamingMediaPlayer(this, textStreamed, playButton, streamButton,progressBar);
audioStreamer.startStreaming("http://r35798.ovh.net:8000/listen",1677, 214);
streamButton.setEnabled(false);
} catch (IOException e) {
}
}
private void Inizializza()
{
textStreamed = (TextView) findViewById(R.id.text_kb_streamed);
streamButton = (Button) findViewById(R.id.button_stream);
streamButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
startStreamingAudio();
}});
playButton = (ImageButton) findViewById(R.id.button_play);
playButton.setEnabled(false);
playButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (audioStreamer.getMediaPlayer().isPlaying()) {
audioStreamer.getMediaPlayer().pause();
playButton.setImageResource(R.drawable.button_play);
} else {
audioStreamer.getMediaPlayer().start();
audioStreamer.startPlayProgressUpdater();
playButton.setImageResource(R.drawable.button_pause);
}
isPlaying = !isPlaying;
}});
}
private class SwipeyTabsPagerAdapter extends FragmentPagerAdapter implements
SwipeyTabsAdapter {
private final Context mContext;
public SwipeyTabsPagerAdapter(Context context, FragmentManager fm) {
super(fm);
this.mContext = context;
}
@Override
public Fragment getItem(int position) {
return SwipeyTabFragment.newInstance(TITLES[position]);
}
@Override
public int getCount() {
return TITLES.length;
}
public TextView getTab(final int position, SwipeyTabs root) {
TextView view = (TextView) LayoutInflater.from(mContext).inflate(
R.layout.swipey_tab_indicator, root, false);
view.setText(TITLES[position]);
view.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
mViewPager.setCurrentItem(position);
}
});
return view;
}
}
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
public void onPageSelected(int arg0) {
// TODO Auto-generated method stub
}
//////////////////////////////////////
@Override
public boolean onCreateOptionsMenu(Menu menu) {
menu.add("Uscita").setOnMenuItemClickListener(
new OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
Toast.makeText(getApplicationContext(),
"Uscita Programma", Toast.LENGTH_SHORT).show();
finish();
System.exit(0);
return true;
}
});
;
return true;
}
public class IceCastPoll extends TimerTask {
public IceCastPoll() {
}
@TargetApi(9)
public void run() {
Scraper scraper = new IceCastScraper();
try {
List<Stream> streams=null;
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
streams = scraper.scrape(new URI("http://r35798.ovh.net:8000"));
for (Stream stream: streams) {
Toast.makeText(getApplicationContext(),stream.getCurrentSong(), Toast.LENGTH_LONG).show();
//textSong.setText((stream.getCurrentSong()));
}
}
catch (URISyntaxException e) {
System.out.println(e.getMessage());
}
catch (ScrapeException e) {
System.out.println(e.getMessage());
}
}
}
class AsyncTaskProc extends AsyncTask<Void, String, Void> {
List<Stream> streams=null;
protected void onPostExecute()
{
textSong =(TextView) findViewById(R.id.textViewCurrentSong);
try {
for (Stream stream: streams) {
textSong.setText((stream.getCurrentSong()));
}
} catch (Exception e) {
//Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_SHORT).show();
}
}
@TargetApi(9)
@Override
protected Void doInBackground(Void... unused) {
Scraper scraper = new IceCastScraper();
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
try {
streams = scraper.scrape(new URI("http://r35798.ovh.net:8000/"));
} catch (ScrapeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
//Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_LONG).show();
} catch (URISyntaxException e) {
// TODO Auto-generated catch block
e.printStackTrace();
//Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_LONG).show();
}
return (null);
}
}
}
当我尝试编译并运行应用程序崩溃时，我无法理解为什么。 感谢;
答案 0 :(得分：1)
这是堆栈的重要部分：
Caused by: java.lang.NullPointerException
at com.example.appuniradiocesena.SwipeyTabsSampleActivity.onCreate(SwipeyTabsSampleActivity.java:77)
- ＆GT;您应该通过查看NullPointerException的第77行找到SwipeyTabsSampleActivity.java的原因。
也许您在布局中不存在的ID上调用findViewById()？ （这会使此方法返回null）