Develop Reference

save audio file using MediaStore API

I'm trying to create the URI but my app crached.this is my code.
ContentValues values1 = new ContentValues(1);
values1.put(MediaStore.Audio.Media.DISPLAY_NAME, "My Song.mp3");
ContentResolver resolver = getApplicationContext().getContentResolver();
audiouri = resolver.insert(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, values1);
And this is the error that i got.
2021-09-20 00:22:22.963 24197-24197/com.example.voicetest E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.voicetest, PID: 24197
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.lastIndexOf(int)' on a null object reference
at android.os.Parcel.createException(Parcel.java:1956)
at android.os.Parcel.readException(Parcel.java:1918)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:183)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:135)
at android.content.ContentProviderProxy.insert(ContentProviderNative.java:476)
at android.content.ContentResolver.insert(ContentResolver.java:1587)
at com.example.voicetest.MainActivity$1.onClick(MainActivity.java:148)
at android.view.View.performClick(View.java:7044)
at android.view.View.performClickInternal(View.java:7017)
at android.view.View.access$3200(View.java:784)
at android.view.View$PerformClick.run(View.java:26596)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6819)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:497)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:912)
UPDATE
I added this code and it's work fine, but getContentResolver().insert() return null
File directory = getExternalFilesDir(Environment.DIRECTORY_MUSIC);
values.put(MediaStore.Audio.AudioColumns.DATA, "${directory}${song?.title}");

File directory = getExternalFilesDir(Environment.DIRECTORY_MUSIC);
values.put(MediaStore.Audio.AudioColumns.DATA, "${directory}${song?.title}");
I added this code and it's work fine, but getContentResolver().insert() return null

Getting list of device ringtones, weird error on 1 emulator?

I get the following error:
java.lang.IllegalArgumentException: Volume external_primary not found
But this only happens on 1 emulator I am running. It works fine on other emulators or my physical android phone.
Here is the code I am trying to run that causes the issue:
private fun listRingtones(): LinkedHashMap<String, String> {
var manager = RingtoneManager(this)
manager.setType(RingtoneManager.TYPE_NOTIFICATION)
var cursor: Cursor = manager.cursor
var list = LinkedHashMap<String, String>()
while (cursor.moveToNext()) {
var title: String = cursor.getString(RingtoneManager.TITLE_COLUMN_INDEX)
var ringtoneURI: Uri = manager.getRingtoneUri(cursor.position)
// Place the title and uri into a hashMap
list.put(title, ringtoneURI.toString())
}
return list
}
Specifically the debugger craps out on this line:
var cursor: Cursor = manager.cursor
Anyone seen anything like this or what could be the cause?
Here is the full error:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.package.mypackage, PID: 7370
java.lang.IllegalArgumentException: Volume external_primary not found
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:170)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:140)
at android.content.ContentProviderProxy.query(ContentProviderNative.java:423)
at android.content.ContentResolver.query(ContentResolver.java:944)
at android.content.ContentResolver.query(ContentResolver.java:880)
at android.content.ContentResolver.query(ContentResolver.java:836)
at android.app.Activity.managedQuery(Activity.java:3111)
at android.media.RingtoneManager.query(RingtoneManager.java:646)
at android.media.RingtoneManager.getMediaRingtones(RingtoneManager.java:579)
at android.media.RingtoneManager.getMediaRingtones(RingtoneManager.java:571)
at android.media.RingtoneManager.getCursor(RingtoneManager.java:437)
at com.package.mypackage.NewReminderActivity.listRingtones(NewReminderActivity.kt:899)
at com.package.mypackage.NewReminderActivity.access$listRingtones(NewReminderActivity.kt:61)
at com.package.mypackage.NewReminderActivity$showSoundMenuAlert$2.onClick(NewReminderActivity.kt:1120)
at android.view.View.performClick(View.java:7140)
at android.view.View.performClickInternal(View.java:7117)
at android.view.View.access$3500(View.java:801)
at android.view.View$PerformClick.run(View.java:27351)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Why can't filereader find my file? [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 6 years ago.
My app won't launch and points to a Null Pointer Exception on my FileReader fr. I initialized it as null to prevent a "Variable may not have been initialized" error. I know the file I want it to use is there under downloads. The file is also inside the main project folder and putting just "academiccalendar.json" does not work either.
My main activity:
public class MainActivity extends AppCompatActivity {
Event[] mobileArray;
Gson gson = new Gson();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BufferedReader br;
FileReader fr = null;
try {
fr = new FileReader("C:/Users/Ali/Downloads/academiccalendar.json");
}
catch (FileNotFoundException e){
e.printStackTrace();
}
br = new BufferedReader(fr);
//br = new BufferedReader(new FileReader("C:/Users/Ali/Downloads/academiccalendar.json"));
mobileArray = gson.fromJson(br, Event[].class);
My logcat output:
12-31 20:06:37.368 9449-9449/com.example.test.testassigment E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test.testassigment/com.example.test.testassigment.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
at android.app.ActivityThread.access$600(ActivityThread.java:127)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4511)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:976)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:743)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:64)
at java.io.BufferedReader.<init>(BufferedReader.java:92)
at java.io.BufferedReader.<init>(BufferedReader.java:80)
at com.example.test.testassigment.MainActivity.onCreate(MainActivity.java:42)
at android.app.Activity.performCreate(Activity.java:4486)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1052)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992) 
at android.app.ActivityThread.access$600(ActivityThread.java:127) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4511) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511)

"C:/Users/Ali/Downloads/academiccalendar.json"
That is a path on your Windows PC. Windows uses drive letters.
Your Android app cannot read files from your PC of course. Or from mine ;-).
I suppose your Android app wants to read a file which is on your Android device.
Try to determine the file on the file system of your Android device.

Because of your path defination. You can use this:
fr = new FileReader("C:\\Users\\Ali\\Downloads\\academiccalendar.json");

I can't get resources using java class .error: Attempt to invoke virtual method

Any one can help me I can't find how I can fix this error
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
import java.util.ArrayList;
import java.util.List;
/**
* Created by Ineza on 18/11/2016.
*/
public class DerpData extends Application {
private static Context mContext;
#Override
public void onCreate() {
super.onCreate();
mContext = this;
}
public static Context getContext(){
return mContext;
}
private static final String[] titles = DerpData.getContext().getResources().getStringArray(R.array.listArray);
private static final int[] icons =DerpData.getContext().getResources().getIntArray(R.array.imgs);
public static List<LisItem> getListData() {
List<LisItem> data = new ArrayList<>();
//Repeat process 4 times, so that we have enough data to demonstrate a scrollable
//RecyclerView
for (int x = 0; x < 4; x++) {
//create ListItem with dummy data, then add them to our List
for (int i = 0; i < titles.length && i < icons.length; i++) {
LisItem item = new LisItem();
item.setImageResId(icons[i]);
item.setTittle(titles[i]);
data.add(item);
}
}
return data;
}
}
Here is a part of logcat
11-19 06:07:42.188 6497-6497/com.example.ineza.assthree E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ineza.assthree, PID: 6497
java.lang.ExceptionInInitializerError
at com.example.ineza.assthree.RecyClerViewActivity.onCreate(RecyClerViewActivity.java:27)
at android.app.Activity.performCreate(Activity.java:6664)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at com.example.ineza.assthree.model.DerpData.<clinit>(DerpData.java:30)
at com.example.ineza.assthree.RecyClerViewActivity.onCreate(RecyClerViewActivity.java:27) 
at android.app.Activity.performCreate(Activity.java:6664) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
11-19 06:07:42.223 1326-1337/system_process W/ActivityManager: Force finishing activity com.example.ineza.assthree/.RecyClerViewActivity
11-19 06:07:42.284 1326-1337/system_process W/ActivityManager: Force finishing activity com.example.ineza.assthree/.LVCustomActivity
11-19 06:07:42.348 1326-1326/system_process W/art: Long monitor contention with owner Binder:1326_1 (1337) at void com.android.server.am.AppErrors.crashApplicationInner(com.android.server.am.Proc essRecord, android.app.ApplicationErrorReport$CrashInfo)(AppErrors.java:328) waiters=0 in int com.android.server.am.ActivityManagerService.broadcastIntent(android.app.IApplicationThread, android.content.Intent, java.lang.String, android.content.IIntentReceiver, int, java.lang.String, android.os.Bundle, java.lang.String[], int, android.os.Bundle, boolean, boolean, int) for 144ms
11-19 06:07:42.561 1326-1343/system_process E/BatteryStatsService: power: Missing API
11-19 06:07:42.562 1326-1375/system_process D/WifiNative-HAL: Failing getSupportedFeatureset because HAL isn't started
11-19 06:07:42.569 1326-1343/system_process E/BluetoothAdapter: Bluetooth binder is null
11-19 06:07:42.571 1326-1343/system_process E/BatteryStatsService: no controller energy info supplied
11-19 06:07:42.620 1326-1343/system_process E/BatteryStatsService: modem info is invalid: ModemActivityInfo{ mTimestamp=0 mSleepTimeMs=0 mIdleTimeMs=0 mTxTimeMs[]=[0, 0, 0, 0, 0] mRxTimeMs=0 mEnergyUsed=0}
11-19 06:07:42.723 1326-2409/system_process I/OpenGLRenderer: Initialized EGL, version 1.4

The code is trying to access static variable from static context when initializing the class. The static initializers are executed before any instance of the class is created. The mContext is initialized after the instance creation during the lifecycle callback. Change your code like this (Updated according to comment below):
#Override
public void onCreate() {
super.onCreate();
mContext = this;
titles = mContext.getResources().getStringArray(R.array.listArray);
icons = mContext.getResources().getIntArray(R.array.imgs);
}
private static final String[] titles;
private static final int[] icons;

java.lang.NullPointerException: Attempt to get length of null array [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 7 years ago.
I am new to Java and android development. I am interested to build an app that can sync a folder from my android phone (Nexus5) to Amazon Web service (AWS). I am trying to build based on an open source project. But, I get the following error for this snippet and unable to locate my mistake. Your feedback will be highly useful at this point.
private void loadFileList(File path) {
this.currentPath = path;
List<String> r = new ArrayList<String>();
if (path.exists()) {
if (path.getParentFile() != null) r.add(PARENT_DIR);
FilenameFilter filter = new FilenameFilter() {
public boolean accept(File dir, String filename) {
File sel = new File(dir, filename);
if (!sel.canRead()) return false;
if (selectDirectoryOption) return sel.isDirectory();
else {
boolean endsWith = fileEndsWith != null ? filename.toLowerCase().endsWith(fileEndsWith) : true;
return endsWith || sel.isDirectory();
}
}
{
FileDialog a = FileDialog.this;
//a.super();
}
};
String[] fileList1 = path.list(filter);
for (String file : fileList1) { <-- Error in this line
r.add(file);
}
}
fileList = (String[]) r.toArray(new String[0]);
}
Error:
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: FATAL EXCEPTION: main
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: Process: pavan.syncfile, PID: 24102
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: java.lang.NullPointerException: Attempt to get length of null array
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at pavan.syncfile.FileDialog.loadFileList(FileDialog.java:149)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at pavan.syncfile.FileDialog.<init>(FileDialog.java:45)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at pavan.syncfile.SendFile$1.onClick(SendFile.java:56)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at android.view.View.performClick(View.java:5198)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at android.view.View$PerformClick.run(View.java:21147)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:739)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:95)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at android.os.Looper.loop(Looper.java:148)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5417)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
11-30 01:03:23.880 24102-24102/pavan.syncfile E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

The intent of this line
String[] fileList1 = path.list(filter); is to list the subfiles in the directory.
Here you are getting fileList1[] are null as there is not subfiles in the path folder matching the filter.
You can add a null check before this line
for (String file : fileList1) { <-- Error in this line
r.add(file);
}
i.e
if(fileList1!=null)
{
for (String file : fileList1) { <-- Error in this line
r.add(file);
}
}