Question

我正在尝试录音机应用程序，我希望在列表视图中显示它。如果我停止录制，则应将录制的文件添加到ListView中。这应该发生在每一站。但我不知道是否以正确的方式编写代码。我在MainActivity中遇到NullpointerException错误。

这是我的MainActivity代码。

public class MainActivity extends Activity {
private ListView mainListView ;
private ArrayAdapter<String> listAdapter;
private MediaRecorder myAudioRecorder;
   private String outputFile = null;
   private Button start,stop,play;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      mainListView = (ListView) findViewById( R.id.mainListView );
      start = (Button)findViewById(R.id.button1);
      stop = (Button)findViewById(R.id.button2);
      play = (Button)findViewById(R.id.button3);
      stop.setEnabled(false);
      play.setEnabled(false);
      outputFile = Environment.getExternalStorageDirectory().
      getAbsolutePath() + "/myrecording.3gp";         
      myAudioRecorder = new MediaRecorder();
      myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
      myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
      myAudioRecorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
      myAudioRecorder.setOutputFile(outputFile);
      ArrayList<String> planetList = new ArrayList<String>();
      planetList.addAll( Arrays.asList(outputFile) );
      listAdapter = new ArrayAdapter<String>(this, R.layout.simplerow, planetList);
      mainListView.setAdapter( listAdapter );  
   }

   public void start(View view){
      try {
         myAudioRecorder.prepare();
         myAudioRecorder.start();
      } catch (IllegalStateException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
      start.setEnabled(false);
      stop.setEnabled(true);
      Toast.makeText(getApplicationContext(), "Recording started", Toast.LENGTH_LONG).show();

   }

   public void stop(View view){
      myAudioRecorder.stop();
      myAudioRecorder.release();
      myAudioRecorder  = null;
      stop.setEnabled(false);
      play.setEnabled(true);
      Toast.makeText(getApplicationContext(), "Audio recorded successfully",
      Toast.LENGTH_LONG).show();
   }
   @Override
   public boolean onCreateOptionsMenu(Menu menu) {
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.main, menu);
      return true;
   }
   public void play(View view) throws IllegalArgumentException,   
   SecurityException, IllegalStateException, IOException{

   MediaPlayer m = new MediaPlayer();
   m.setDataSource(outputFile);
   m.prepare();
   m.start();
   Toast.makeText(getApplicationContext(), "Playing audio", Toast.LENGTH_LONG).show();
   //play.setEnabled(toggle);
   }

 }

这是我的activity_main.xml代码

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:paddingBottom="@dimen/activity_vertical_margin"
 android:paddingLeft="@dimen/activity_horizontal_margin"
 android:paddingRight="@dimen/activity_horizontal_margin"
 android:paddingTop="@dimen/activity_vertical_margin"
 tools:context=".MainActivity" >

 <TextView
  android:id="@+id/textView1"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_alignParentLeft="true"
  android:layout_alignParentRight="true"
  android:layout_alignParentTop="true"
  android:layout_marginTop="32dp"
  android:text="@string/Recording"
  android:textAppearance="?android:attr/textAppearanceMedium" />

  <ImageView
  android:id="@+id/imageView1"
  android:layout_width="100dp"
  android:layout_height="100dp"
  android:layout_below="@+id/textView1"
  android:layout_centerHorizontal="true"
  android:layout_marginTop="37dp"
  android:scaleType="fitXY"
  android:src="@drawable/microphone" />

  <Button
  android:id="@+id/button1"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_below="@+id/imageView1"
  android:layout_marginTop="67dp"
  android:layout_toLeftOf="@+id/imageView1"
  android:onClick="start"
  android:text="@string/start" />

  <Button
  android:id="@+id/button2"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_alignBaseline="@+id/button1"
  android:layout_alignBottom="@+id/button1"
  android:layout_alignRight="@+id/textView1"
  android:layout_marginRight="40dp"
  android:onClick="stop"
  android:text="@string/stop" />

  <Button
  android:id="@+id/button3"
  style="?android:attr/buttonStyleSmall"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_below="@+id/button2"
  android:layout_centerHorizontal="true"
  android:onClick="play"
  android:text="@string/play" />

  </RelativeLayout>

这是main_listview.xml代码

  <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">

  <ListView android:layout_width="fill_parent" 
  android:layout_height="fill_parent" 
  android:id="@+id/mainListView">
  </ListView>

  </LinearLayout>

这是我的simplerow.xml代码

 <TextView xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/rowTextView" 
 android:layout_width="fill_parent" 
 android:layout_height="wrap_content"
 android:padding="10dp"
 android:textSize="16sp" >
 </TextView>

请纠正我。提前谢谢。

Answer 1

使用文件实用程序类从存储中获取音频文件

public class ListFilesUtil {

     public static List<String> listFiles(String directoryName) {
        List<String> fileName = new ArrayList<String>();


directoryName, Context.MODE_PRIVATE).getParentFile();

        File directory = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + directoryName);
        //get all the files from a directory
        File[] fList = directory.listFiles();
        if (fList != null) {
            for (File file : fList) {
                if (file.isFile()) {
                    fileName.add(file.getName());
                }
            }
        }
        return fileName;
    }

    public static List<String> listFolders( String directoryName) {
        List<String> fileName = new ArrayList<String>();


directoryName, Context.MODE_PRIVATE).getParentFile();

        File directory = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + directoryName);
        //get all the files from a directory
        File[] fList = directory.listFiles();
        if (fList != null) {
            for (File file : fList) {
                if (file.isDirectory()) {
                    fileName.add(file.getName());
                }
            }
        }

        Collections.sort(fileName);
        return fileName;
    }

}

无法在ListView中显示音频录制文件？

1 个答案: