【发布时间】：2021-08-13 07:07:26
【问题描述】：
我正在尝试制作一个音乐应用程序，每当我尝试向其上传歌曲时应用程序崩溃，错误是：
2021-05-25 04:51:02.446 24439-24439/com.example.msctry E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.msctry, PID: 24439
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=101, result=-1, data=Intent { dat=content://com.android.providers.downloads.documents/document/msf:7900 flg=0x1 }} to activity {com.example.msctry/com.example.msctry.MainActivity}: java.lang.NullPointerException: Attempt to get length of null array
at android.app.ActivityThread.deliverResults(ActivityThread.java:5097)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5138)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2147)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:7814)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)
Caused by: java.lang.NullPointerException: Attempt to get length of null array
at com.example.msctry.MainActivity.onActivityResult(MainActivity.java:112)
at android.app.Activity.dispatchActivityResult(Activity.java:8292)
at android.app.ActivityThread.deliverResults(ActivityThread.java:5090)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5138)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2147)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:7814)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)
起初我以为我只是没有提供内部存储权限，所以我做了，但它仍然发生，这是我的清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.msctry">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:requestLegacyExternalStorage="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.MscTry">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
这是主要的活动文件：
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
TextView TextimageView;
ProgressBar progressBar;
Uri audiouri;
StorageReference mstorage;
StorageTask mUploadTask;
DatabaseReference reference;
String songsCategory;
MediaMetadataRetriever mediaMetadataRetriever;
byte[] art;
String title1,artist1,album_art1="",duration1;
TextView title,artist,durations,album,dataa;
ImageView album_art;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextimageView=findViewById(R.id.tvuploadsongfileselected);
progressBar=findViewById(R.id.progressbar);
title=findViewById(R.id.title);
artist=findViewById(R.id.artist);
durations=findViewById(R.id.duration);
album=findViewById(R.id.album);
dataa=findViewById(R.id.data);
album_art=findViewById(R.id.img);
mediaMetadataRetriever=new MediaMetadataRetriever();
reference= FirebaseDatabase.getInstance().getReference().child("songs");
mstorage= FirebaseStorage.getInstance().getReference().child("songs");
Spinner spinner=findViewById(R.id.spinner);
spinner.setOnItemSelectedListener(this);
List<String> categories=new ArrayList<>();
categories.add("Jogging Songs");
categories.add("Swimming Exercise Songs");
categories.add("Aerobic Songs");
categories.add("Walking Songs");
categories.add("Biking Songs");
categories.add("Physical Therapy Songs");
ArrayAdapter<String> dataAdapter=new ArrayAdapter<>(this, android.R.layout.simple_spinner_item,categories);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(dataAdapter);
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
songsCategory=parent.getItemAtPosition(position).toString();
Toast.makeText(this, "Selected"+songsCategory, Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
public void openAudioFiles(View v){
Intent i=new Intent(Intent.ACTION_GET_CONTENT);
i.setType("audio/*");
startActivityForResult(i,101);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode==101&& resultCode==RESULT_OK && data.getData()!=null){
audiouri=data.getData();
String fileNames=getFileName(audiouri);
TextimageView.setText(fileNames);
mediaMetadataRetriever.setDataSource(this,audiouri);
art=mediaMetadataRetriever.getEmbeddedPicture();
Bitmap bitmap= BitmapFactory.decodeByteArray(art,0,art.length);
album_art.setImageBitmap(bitmap);
album.setText(mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ALBUM));
artist.setText(mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ARTIST));
dataa.setText(mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_GENRE));
durations.setText(mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION));
title.setText(mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_TITLE));
artist1=mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ARTIST);
title1=mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_TITLE);
duration1=mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
}
}
private String getFileName(Uri uri){
String result=null;
if(uri.getScheme().equals("content")){
Cursor cursor=getContentResolver().query(uri,null,null,null,null);
try {
if (cursor != null && cursor.moveToFirst()) {
result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
}
}finally {
cursor.close();
}
}
if(result==null){
result=uri.getPath();
int cut=result.lastIndexOf('/');
if(cut!=-1){
result=result.substring(cut+1);
}
}
return result;
}
public void uploadFileToFirebase(View v){
if(TextimageView.equals("No file Selected")){
Toast.makeText(this, "please select an image!", Toast.LENGTH_SHORT).show();
}else{
if(mUploadTask!=null&& mUploadTask.isInProgress()){
Toast.makeText(this, "song upload is in progress !", Toast.LENGTH_SHORT).show();
}else{
uploadFiles();
}
}
}
private void uploadFiles() {
if(audiouri!=null) {
Toast.makeText(this, "Song Is Uploading Please Wait", Toast.LENGTH_SHORT).show();
progressBar.setVisibility(View.VISIBLE);
final StorageReference storageReference = mstorage.child(System.currentTimeMillis() + "." + getfileextension(audiouri));
mUploadTask = storageReference.putFile(audiouri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
storageReference.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
UploadSong uploadSong = new UploadSong(songsCategory, title1, artist1, album_art1, duration1, uri.toString());
String uploadId = reference.push().getKey();
reference.child(uploadId).setValue(uploadSong);
}
});
}
}).addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
@Override
public void onProgress(@NonNull UploadTask.TaskSnapshot snapshot) {
double progress = (100.0 * snapshot.getBytesTransferred() / snapshot.getTotalByteCount());
progressBar.setProgress((int) progress);
}
});
}else{
Toast.makeText(this, "No file Selected to Upload", Toast.LENGTH_SHORT).show();
}
}
private String getfileextension(Uri audiouri){
ContentResolver contentResolver=getContentResolver();
MimeTypeMap mimeTypeMap=MimeTypeMap.getSingleton();
return mimeTypeMap.getExtensionFromMimeType(contentResolver.getType(audiouri));
}
}
错误发生在以下行：
Bitmap bitmap= BitmapFactory.decodeByteArray(art,0,art.length);
由于某种原因，他们无法获得我要上传的歌曲的长度，我不明白为什么，我尝试在另一部手机上运行该应用程序，当我从某个音乐播放器中选择歌曲时应用程序崩溃了，当我从音频中崩溃时它没有崩溃，但它在我的实际手机中根本不起作用
【问题讨论】：
-
也许该歌曲文件没有嵌入图片？
-
确保在
art不为空时调用length，否则你会得到NPE。 -
@AlexMamo 怎么样？
-
@lyncx 我不确定这是从 youtube 到 mp3 转换器的文件
-
检查无效。
标签： android arrays firebase error-handling