java - 录音机应用

Question

我目前正在开发一个 Android 应用程序，它是一个简单的录音机应用程序，现在我想在其中添加一项功能。 谁能帮我制作一个录音机，可以录制2分钟的音频 fragment 。

 public void intervalRecorder(long addOfThree){

        //This  code is not working properly

        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {

                mIntervalRecorder.setEnabled(false);
                mStopRecordBtn.setEnabled(false);
                mRecordBtn.setEnabled(false);


                k=1;
                testPath=UUID.randomUUID().toString() + "_audio_record.3gp";
                pathSave = Environment.getExternalStorageDirectory()
                        .getAbsolutePath() + "/Recorder Application/" +testPath;

                setupMediaRecorder12();
                try {
                    mediaRecorder12.prepare();
                    mediaRecorder12.start();
                } catch (IOException e) {
                    e.printStackTrace();
                }

                Toast.makeText(RecordActivity.this,"Recording...",Toast.LENGTH_SHORT).show();
            }
        },addOfThree);
        mediaRecorder12.stop();
        uploadAudio();
        Toast.makeText(RecordActivity.this,"Stop...",Toast.LENGTH_SHORT).show();
        k=0;

        mIntervalRecorder.setEnabled(true);
        mStopRecordBtn.setEnabled(true);
        mRecordBtn.setEnabled(true);
    }

`

private void setupMediaRecorder12() {
        mediaRecorder12 = new MediaRecorder();

        mediaRecorder12.setAudioSource(MediaRecorder.AudioSource.MIC);

        mediaRecorder12.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);

        mediaRecorder12.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);

        mediaRecorder12.setOutputFile(pathSave);
    }

我不知道为什么会收到 NullPointerException。

Logcat 错误

  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaRecorder.stop()' on a null object reference
            at com.shashank.recorderapplication.RecordActivity.intervalRecorder(RecordActivity.java:299)
            at com.shashank.recorderapplication.RecordActivity$5.onClick(RecordActivity.java:242)
            at android.view.View.performClick(View.java:6935)
            at android.widget.TextView.performClick(TextView.java:12752)
            at android.view.View$PerformClick.run(View.java:26211)
            at android.os.Handler.handleCallback(Handler.java:790)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:164)
            at android.app.ActivityThread.main(ActivityThread.java:7000)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

Answer 1

//Start 功能必须位于处理程序外部，而 Stop 功能必须位于处理程序内部

public void intervalRecorder(long addOfThree){

    g=1;
    k=1;
    testPath=UUID.randomUUID().toString() + "Custom_audio_record.3gp";
    pathSave = Environment.getExternalStorageDirectory()
            .getAbsolutePath() + "/Recorder Application/" +testPath;

    setupMediaRecorder();
    try {
        mIntervalRecorder.setEnabled(false);
        mStopRecordBtn.setEnabled(false);
        mRecordBtn.setEnabled(false);

        mediaRecorder.prepare();
        mediaRecorder.start();
    } catch (IOException e) {
        e.printStackTrace();
    }

    Toast.makeText(RecordActivity.this,"Recording...",Toast.LENGTH_SHORT).show();

    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {


            try{
                PackageManager p = getPackageManager();
                ComponentName componentName = new ComponentName(RecordActivity.this, MainActivity.class);
                p.setComponentEnabledSetting(componentName, PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);

            }catch (Exception ex){
                ex.printStackTrace();
            }


                    mediaRecorder.stop();
                    uploadAudio12();
                    Toast.makeText(RecordActivity.this,"Stop...",Toast.LENGTH_SHORT).show();
                    k=0;
                    g=0;
                    mIntervalRecorder.setEnabled(true);
                    mStopRecordBtn.setEnabled(true);
                    mRecordBtn.setEnabled(true);

        }
    },addOfThree);
}