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Basic recording example

This example shows the simplest way to record audio with AMRAudioRecorder. 
// Set up the recording directory
String sdcardPath = Environment.getExternalStorageDirectory().getAbsolutePath();
String recordingDirectory = sdcardPath + "/recordings/";

File dir = new File(recordingDirectory);
if (!dir.exists()) {
    dir.mkdirs();
}

// Create recorder and start recording
AMRAudioRecorder recorder = new AMRAudioRecorder(recordingDirectory);
recorder.start();

// ... record audio ...

// Stop and get the file path
recorder.stop();
String audioPath = recorder.getAudioFilePath();

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Complete recording activity

This example demonstrates a full Android activity with record, pause, resume, and discard functionality, based on the library’s sample app. 
public class MainActivity extends AppCompatActivity {

    private AMRAudioRecorder mRecorder;
    private TextView mRecordingTime;
    private int mRecordTimeInterval;
    private EasyTimer mAudioTimeLabelUpdater;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRecordingTime = findViewById(R.id.recordingTime);
    }

    public void onToggleRecordClick(View view) {
        if (mRecorder == null) {
            // Start new recording
            startRecording(view);
        } else {
            // Toggle pause/resume
            if (mRecorder.isRecording()) {
                pauseRecording(view);
            } else {
                resumeRecording(view);
            }
        }
    }

    private void startRecording(View view) {
        resetRecording();

        String sdcardPath = Environment.getExternalStorageDirectory().getAbsolutePath();
        String recordingDirectory = sdcardPath + "/wtrecorder/";
        File dir = new File(recordingDirectory);
        if (!dir.exists()) {
            dir.mkdirs();
        }

        mRecorder = new AMRAudioRecorder(recordingDirectory);
        mRecorder.start();

        ((ImageButton) view).setImageResource(R.drawable.ic_pause);

        // Start timer to update recording time label
        mAudioTimeLabelUpdater = new EasyTimer(1000, new EasyTimer.CallBack() {
            @Override
            public void execute() {
                int time = mRecordTimeInterval;
                int min = time / 60, sec = time % 60;
                String minStr = min < 10 ? "0" + min : "" + min;
                String secStr = sec < 10 ? "0" + sec : "" + sec;
                mRecordingTime.setText(minStr + ":" + secStr);
                mRecordTimeInterval++;
            }
        });
    }

    private void pauseRecording(View view) {
        ((ImageButton) view).setImageResource(R.drawable.ic_play);
        mAudioTimeLabelUpdater.stop();
        mRecorder.pause();
    }

    private void resumeRecording(View view) {
        ((ImageButton) view).setImageResource(R.drawable.ic_pause);
        mRecorder.resume();
        mAudioTimeLabelUpdater.restart();
    }

    public void onDoneClick(View view) {
        if (mRecorder == null) {
            return;
        }

        mRecorder.stop();

        // Navigate to playback screen
        Intent intent = new Intent(this, PlaybackActivity.class);
        intent.putExtra("audioFilePath", mRecorder.getAudioFilePath());
        startActivity(intent);

        mRecorder = null;
        resetRecording();
    }

    public void onTrashClick(View view) {
        if (mRecorder == null) {
            return;
        }

        mRecorder.clear();
        mRecorder = null;
        resetRecording();
    }

    private void resetRecording() {
        if (mAudioTimeLabelUpdater != null) {
            mAudioTimeLabelUpdater.stop();
            mAudioTimeLabelUpdater = null;
        }

        mRecordTimeInterval = 0;
        mRecordingTime.setText("00:00");

        ImageButton toggleButton = findViewById(R.id.toggleRecord);
        toggleButton.setImageResource(R.drawable.ic_play);
    }
}

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Handling permissions (Android 6.0+)

For Android Marshmallow (API 23) and above, you must request permissions at runtime. 
private static final int PERMISSION_REQUEST_CODE = 100;
private String[] permissionsList = {
    Manifest.permission.WRITE_EXTERNAL_STORAGE,
    Manifest.permission.RECORD_AUDIO
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    if (Build.VERSION.SDK_INT >= 23) {
        if (!hasPermissions()) {
            requestPermissions(permissionsList, PERMISSION_REQUEST_CODE);
        }
    }
}

private boolean hasPermissions() {
    for (String permission : permissionsList) {
        if (checkSelfPermission(permission) != PackageManager.PERMISSION_GRANTED) {
            return false;
        }
    }
    return true;
}

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    
    if (requestCode == PERMISSION_REQUEST_CODE) {
        boolean allGranted = true;
        for (int result : grantResults) {
            if (result != PackageManager.PERMISSION_GRANTED) {
                allGranted = false;
                break;
            }
        }
        
        if (!allGranted) {
            Toast.makeText(this, "Permissions required for recording", Toast.LENGTH_LONG).show();
            finish();
        }
    }
}

​
Error handling

Handle potential errors when working with AMRAudioRecorder. 
try {
    AMRAudioRecorder recorder = new AMRAudioRecorder(recordingDirectory);
    
    boolean started = recorder.start();
    if (!started) {
        // MediaRecorder failed to prepare
        Toast.makeText(this, "Failed to start recording", Toast.LENGTH_SHORT).show();
        return;
    }
    
    // Recording in progress...
    
    if (recorder.isRecording()) {
        try {
            recorder.pause();
        } catch (IllegalStateException e) {
            Log.e("Recorder", "Cannot pause: not recording", e);
        }
    }
    
    // Resume after pause
    if (!recorder.isRecording()) {
        try {
            recorder.resume();
        } catch (IllegalStateException e) {
            Log.e("Recorder", "Cannot resume: already recording", e);
        }
    }
    
    boolean stopped = recorder.stop();
    if (!stopped) {
        Toast.makeText(this, "Failed to merge recordings", Toast.LENGTH_SHORT).show();
    }
    
} catch (IllegalArgumentException e) {
    // Invalid directory provided
    Log.e("Recorder", "Invalid recording directory", e);
    Toast.makeText(this, "Recording directory not found", Toast.LENGTH_SHORT).show();
}

​
State management pattern

Manage recorder state throughout the activity lifecycle. 
public class RecordingActivity extends AppCompatActivity {
    private AMRAudioRecorder recorder;
    private RecordingState state = RecordingState.IDLE;
    
    enum RecordingState {
        IDLE,
        RECORDING,
        PAUSED
    }
    
    private void updateRecordingState() {
        if (recorder == null) {
            state = RecordingState.IDLE;
        } else if (recorder.isRecording()) {
            state = RecordingState.RECORDING;
        } else {
            state = RecordingState.PAUSED;
        }
        updateUI();
    }
    
    private void updateUI() {
        switch (state) {
            case IDLE:
                recordButton.setImageResource(R.drawable.ic_record);
                recordButton.setEnabled(true);
                doneButton.setEnabled(false);
                break;
                
            case RECORDING:
                recordButton.setImageResource(R.drawable.ic_pause);
                recordButton.setEnabled(true);
                doneButton.setEnabled(true);
                break;
                
            case PAUSED:
                recordButton.setImageResource(R.drawable.ic_resume);
                recordButton.setEnabled(true);
                doneButton.setEnabled(true);
                break;
        }
    }
}

​
Recording with custom storage location

Use app-specific storage for better compatibility with Android 10+ scoped storage. 
// Use app-specific external storage (no permissions needed on Android 10+)
File recordingDir = new File(getExternalFilesDir(null), "recordings");
if (!recordingDir.exists()) {
    recordingDir.mkdirs();
}

AMRAudioRecorder recorder = new AMRAudioRecorder(recordingDir.getAbsolutePath());
recorder.start();

// Later, get the file
recorder.stop();
String audioPath = recorder.getAudioFilePath();
File audioFile = new File(audioPath);

// Share or process the file
if (audioFile.exists()) {
    long fileSizeInBytes = audioFile.length();
    Log.d("Recording", "Saved " + fileSizeInBytes + " bytes to " + audioPath);
}