See also questions close to this topic

• Can not build APK file with buildozer. UnicodeDecodeError

  When I am pack my app with Buildozer for Android, I get an UnicodeDecodeError. Log2 is attached together with Buildozer build.py.

  OS: UBUNTU 16.04.

  I am trying on python 2.7 and 3.5, get same error.

  Link with files: https://yadi.sk/d/F76tP019ZAKRLA
• sending image to another activity

  I am trying to send an image that in ListView from onItemClick to onCreate method in another activity .

  This is my code :

  Activity 1

  product_imageView= findViewById(R.id.product_imageView);
  
  
  byte[] image = savedInstanceState.getByteArray("Product image");
  
   Bitmap receivedImage = BitmapFactory.decodeByteArray(image,0,image.length);
  
  //here it give me error
          product_imageView.setImageResource(receivedImage);
  

  Activity 1

  String productimage = productslist.get(position).getProductImage();
  
  Bundle bundle = new Bundle();
                  bundle.putByteArray("Product image", productimage.getBytes());
                  intent.putExtras(bundle);
                  startActivity(intent);
  
• Doesn't receiver proper data in android from HC05 bluetooth module

  Connection establish properly,when data received from HC05 module then some data misplace or doesn't received like original. Actually module send 8k byte of data and am going to receive in android application.
• How to fit textviews and buttons to all screen sizes in android studio

  Textviews and buttons get all messed up in a different android device. I want to design the app so that it supports all devices. Can anyone help?
• How to not change the color of the label while setting error to particular textinputlayout having edittext inside it?

  I am using a Textinputlayout and edittext inside it, problem is when I set the error to the textinputlayout at the time of validations , it changes the color of my hint label also to red. I want to put another color instead of that red color when error comes.Only the underline color and error text should turn to red.

  

  above shown in the pic is the problem, I dont want the email label with red color.

  Below is my code.

  xml file

       <android.support.design.widget.TextInputLayout
              android:layout_marginTop="30dp"
              android:layout_marginLeft="20dp"
              android:layout_marginRight="20dp"
              android:layout_marginBottom="15dp"
   app:errorTextAppearance="@style/error_appearance"
          app:hintTextAppearance="@style/TextLabel1"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:id="@+id/et1"
              android:padding="0dp">
  
          <EditText
              android:id="@+id/email"
              android:hint="Email"
              android:textColorHint="#3F4B5B"
              android:maxLines="1"
              android:inputType="text"
              android:textSize="15sp"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"/>
  
      </android.support.design.widget.TextInputLayout>
  
  
  #java file
  
  
  #Declarations
   private TextInputLayout emailerror;
   private EditText Email;
  
  #On create 
      Email=(EditText) findViewById(R.id.email);
       emailerror=(TextInputLayout) findViewById(R.id.et1);
  
  #Inside validation method
   emailerror.setError("Enter a valid email");
  

  Style.xml

  <resources>
  
      <!-- Base application theme. -->
      <style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">
          <!-- Customize your theme here. -->
          <item name="colorPrimary">@color/colorPrimary</item>
          <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
          <item name="colorAccent">@color/colorAccent</item>
      </style>
  
      <style name="AppTheme.NoActionBar" parent="Base.Theme.AppCompat.Light.DarkActionBar">
          <item name="windowActionBar">false</item>
          <item name="windowNoTitle">true</item>
           TextInputLayout text color
          <item name="colorControlNormal">#e0e0e0</item>
          <item name="colorControlActivated">#52AF44</item>
          <item name="android:textColorHint">#3F4B5B</item>
          <item name="android:windowFullscreen">true</item>
      </style>
  
  
  <!--    <style name="error" parent="@android:style/TextAppearance">
          <item name="android:textColor">#ff0000</item> &lt;!&ndash;apply the color you wat here &ndash;&gt;
          <item name="android:textColorHint">#3E4A58</item>
         &lt;!&ndash; <item name="android:textColorHint">#3a52a6</item>&ndash;&gt;
         &lt;!&ndash; <item name="android:textSize">12dp</item>&ndash;&gt;
      </style>-->
  
      <!--<style name="Widget.Design.TextInputLayout" parent="AppTheme">
          <item name="hintTextAppearance">@style/TextLabel1</item>
          <item name="errorTextAppearance">@style/error_appearance</item>
          <item name="counterTextAppearance">@style/TextAppearance.Design.Counter</item>
          <item name="counterOverflowTextAppearance">@style/TextAppearance.Design.Counter.Overflow</item>
      </style>-->
  
      <style name="error_appearance" parent="@android:style/TextAppearance">
          <item name="android:textColor">@color/colorAccent</item>
      </style>
  
      <style name="TextLabel1" parent="TextAppearance.Design.Hint">
          <item name="android:textColor">@color/colorPrimaryDark</item>
          <item name="android:textSize">16sp</item>
      </style>
  
      <style name="ToolbarColoredBackArrow" parent="AppTheme">
          <item name="android:textColorSecondary">@color/white</item>
      </style>
  
      <style name="EditTextHint" parent="Theme.AppCompat">
          <!--<item name="colorAccent">@android:color/white</item>-->
          <item name="android:textColorHint">#989898</item>
       <!--   <item name="colorControlNormal">@color/BackgroundtWhiteColor</item>
          <item name="colorControlActivated">@color/your color</item>
          <item name="colorControlHighlight">@color/BackgroundtWhiteColor</item>-->
      </style>
  
      <style name="Widget.App.Spinner" parent="@style/Widget.AppCompat.Spinner">
          <item name="overlapAnchor">true</item>
          <item name="android:background">@drawable/spinner_background</item>
      </style>
  
  </resources>
  
• Fetch an input field into android from php web server

  I have a form that has an input field that captures firstname written in html processed by php using MySQL to send data to user table. Is there a way I can fetch that field into android app, after fetch android creates that firstname input field automatically into SQLite, when user is done capturing data that input is destroyed at session end. I know it’s possible in Java, can it be done in php?
• Compare Two JSONArray's with integer values , If Value is same then change that texview color

  I have two arraylist in my model class which are containing integer values.Im getting both arrays in my adapter and comparing values .I want this, when any value of first array matches with second array then in list that specific list row item text view should be in red color.Arraylist size can be increase and decrease .

  Below I'm providing code .Please review and provide me solution .

  public ArrayList<GetDoctorScheduleDetail> getDoctorScheduleDetails;// parent model class which is containing both bottom arraylist
      public ArrayList<GetBlockedTimings> getBlockedTimingses = new ArrayList<>();
      public ArrayList<AvailableTimeSlots> availableTimeSlotses = new ArrayList<>();
  
       for (int i=0;i<getDoctorScheduleDetails.size();i++)
          {
  
              all_time_id = pojo.getAvailableTimeSlots().get(position).getTimeSlotId();
              compare.add(all_time_id);
              for (int j=0;j<getBlockedTimingses.size();j++) {
                  all_block_id = pojo.getGetBlockedTimings().get(position).getFkTimeId();
                  compare_fk.add(all_block_id);
                  if (all_time_id==all_block_id)
                  {
                     /* if (all_time_id==all_block_id)
                      {*/
                      Toast.makeText(context,"Hi It's matched"+i +""+j,Toast.LENGTH_SHORT).show();
                      Log.e("searching...1",+i+" "+j);
                  }
                  else  if (all_time_id!=all_block_id)  {
                      Toast.makeText(context,"No matched"+i +""+j,Toast.LENGTH_SHORT).show();
                      Log.e("searching...1",+i+" "+j);
                  }
                 /* Log.e("found_first_index: ", i + " second_index: " + j);
                  Log.e("searching... ",+i+" "+j);*/
              }
  
          }
  

  Second JSONarray values are not coming in model class

  public class MyScheduleJSONParser {
      public static final String TAG = "MyScheduleJSONParser";
  
      static ArrayList<GetDoctorScheduleDetail> doctorScheduleDetailList; // parent model array object
      static List<AvailableTimeSlots> availableTimeSlotses;// child model array to save 1st json array values object
      static List<GetBlockedTimings> getBlockedTimingses;// child model array to save 2nd json array values object
  
      public static ArrayList<GetDoctorScheduleDetail> parseData(String content, int index) {
          try {
              JSONObject jsonObject = new JSONObject(content);
              JSONArray details_jsonArray = jsonObject.getJSONArray("Detail");
  
              doctorScheduleDetailList = new ArrayList<>();
              availableTimeSlotses = new ArrayList<>();
              getBlockedTimingses = new ArrayList<>();
  
              JSONObject detailObject = details_jsonArray.getJSONObject(index);
             // for (int i = 0; i <= detailObject.length(); i++) {
                  GetDoctorScheduleDetail slot = new GetDoctorScheduleDetail();//parent model class in this I'm storing other parameters rather then 2 jsonarry(AvailableTimeSlots,GetBlockedTimings)
                  slot.setDateOfSlot(detailObject.getString("DateOfSlot"));
                  slot.setScheduleId(detailObject.getInt("ScheduleId"));
                  slot.setBlockId(detailObject.getInt("BlockId"));
                  slot.setFkTimeId(detailObject.getInt("fkTimeId"));
                  slot.setDeleted(detailObject.getBoolean("IsDeleted"));
                  slot.setFkScheduledId(detailObject.getInt("fkScheduledId"));
                  slot.setUtcDateOfSlot(detailObject.getString("utcDateOfSlot"));
  
  
                  /* this is to fetch AvailableTimeSlots data*/
                  JSONArray availableTimeSlots = detailObject.getJSONArray("AvailableTimeSlots");
  
                  /* this loop for fetch AvailableTimeSlots data*/
                  for (int j = 0; j < availableTimeSlots.length(); j++) {
                      JSONObject innerDataObject = availableTimeSlots.getJSONObject(j);
  
                      AvailableTimeSlots timeSlots = new AvailableTimeSlots();//child model to save available array data
                      timeSlots.setTimeOfSlot(innerDataObject.getString("TimeOfSlot"));
                      timeSlots.setTimeSlotId(innerDataObject.getInt("TimeSlotId"));
                      timeSlots.setTimeofSlotDateTime(innerDataObject.getString("TimeofSlotDateTime"));
                      availableTimeSlotses.add(timeSlots);// adding data in child model list
                      slot.setAvailableTimeSlots(availableTimeSlotses);// adding data in parent model   public void setAvailableTimeSlots(List<AvailableTimeSlots> availableTimeSlots){this.availableTimeSlots = availableTimeSlots;}
                      doctorScheduleDetailList.add(slot);// adding in parent list
                  }
                  /* this loop to fetch GetBlockedTimings data*/
  
                  if ((detailObject.getJSONArray("GetBlockedTimings")) != null) {
                      JSONArray getBlockedTimings = detailObject.getJSONArray("GetBlockedTimings");
                      /* this loop for fetch GetBlockedTimings data*/
                      for (int k = 0; k < getBlockedTimings.length(); k++) {
                          JSONObject getBlockedTimingsJSONObject = getBlockedTimings.getJSONObject(k);
                          GetBlockedTimings blockedTimings = new GetBlockedTimings();
                          blockedTimings.setFkTimeId(getBlockedTimingsJSONObject.getInt("fkTimeId"));
  
                          getBlockedTimingses.add(blockedTimings);// adding data in child model list
                          slot.setGetBlockedTimings(getBlockedTimingses);//adding data in parent model public void setGetBlockedTimings(List<GetBlockedTimings> getBlockedTimings){this.getBlockedTimings = getBlockedTimings;}
                          doctorScheduleDetailList.add(slot);// adding in parent list
                      }
                      //doctorScheduleDetailList.add(slot);
                      return doctorScheduleDetailList;
                  }
            //  }
          } catch (JSONException e) {
              e.printStackTrace();
          }
          return doctorScheduleDetailList;
      }
  }
• Problem with Android Studio InstrumentedTest with Room

  I can't figure out why my instrumented unit test fails at the position indicated in the first code block below. As far as I can see, I've followed the demonstrated cases online for using the Room persistence library, with the test based on the android developer site. Code being tested is derived from the google "room with a view" codelab. The test inserts an object and reads a list of those objects, wrapped as LiveData. The object just inserted should be in the returned list, however null is returned in LiveData.

  The test case:

  @RunWith(AndroidJUnit4.class)
  public class PersonReadWriteTest
  {
  private PersonDAO personDao;
  private EventDatabase database;
  
  @Before
  public void createDb ()
  {
      Context appContext = InstrumentationRegistry.getTargetContext();
      database = Room.inMemoryDatabaseBuilder(appContext, EventDatabase.class).build();
      personDao = database.personDAO();
  }
  
  @After
  public void closeDb () throws IOException
  {
      database.close();
  }
  
  @Test
  public void writePersonAndReadInList() throws Exception
  {
      Person person = TestUtil.createPerson("John", "Doe");
      personDao.insert(person);
      LiveData<List<Person>> peopleLive = personDao.getAll();
      List<Person> people = peopleLive.getValue();
      assertNotNull(people); <=============================== FAILS HERE
      assertThat(people.size(), equalTo(1));
      Person read = people.get(0);
      assertNotNull(read);
      assertThat(read, equalTo(person));
  }
  }
  

  Test result:

  java.lang.AssertionError
  at org.junit.Assert.fail(Assert.java:86)
  at org.junit.Assert.assertTrue(Assert.java:41)
  at org.junit.Assert.assertNotNull(Assert.java:712)
  at org.junit.Assert.assertNotNull(Assert.java:722)
  at PersonReadWriteTest.writePersonAndReadInList(PersonReadWriteTest.java:69)
  at java.lang.reflect.Method.invoke(Native Method)
  at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
  at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
  at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
  at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
  at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
  at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
  at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
  at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
  at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
  at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
  at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
  at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
  at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
  at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
  at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
  at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:101)
  at org.junit.runners.Suite.runChild(Suite.java:128)
  at org.junit.runners.Suite.runChild(Suite.java:27)
  at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
  at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
  at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
  at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
  at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
  at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
  at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
  at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
  at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
  at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:384)
  at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:2106)
  

  Person entity:

  @Entity(tableName="people")
  public class Person implements Serializable
  {
  // ---------------------------------------------------------------
  // Attributes
  
  @PrimaryKey
  private Long id = null;
  @ColumnInfo(name="first_name")
  private String firstName = null;
  @ColumnInfo(name="last_name")
  private String surname = null;
  @ColumnInfo(name="address")
  private String address = null;
  @ColumnInfo(name="phone1")
  private String phone1 = null;
  @ColumnInfo(name="phone2")
  private String phone2 = null;
  @ColumnInfo(name="email")
  private String email = null;
  
  // ---------------------------------------------------------------
  // Attribute access
  
  ... all the public getters and setters...
  
  // -----------------------------------------------------------------
  
  public Person ()
  {}
  }
  

  DAO:

  @Dao
  public interface PersonDAO
  {
  @Query("SELECT * FROM people")
  LiveData<List<Person>> getAll ();
  
  @Query("SELECT * FROM people WHERE id IN (:ids)")
  LiveData<List<Person>> loadAllByIds (int[] ids);
  
  @Query("SELECT * FROM people WHERE first_name LIKE :first AND last_name LIKE :last LIMIT 1")
  LiveData<Person> findByName (String first, String last);
  
  @Insert(onConflict = OnConflictStrategy.REPLACE)
  void insert (Person person);
  
  @Delete
  void delete (Person person);
  
  @Query("DELETE from people")
  void deleteAll ();
  }
  

  Database class:

  @Database(entities = { Event.class, Person.class }, version = 1)
  public abstract class EventDatabase extends RoomDatabase
  {
  public abstract EventDAO eventDAO ();
  public abstract PersonDAO personDAO ();
  
  private static volatile EventDatabase INSTANCE;
  
  static EventDatabase getDatabase (final Context context)
  {
      if (INSTANCE == null)
      {
          synchronized (EventDatabase.class)
          {
              if (INSTANCE == null)
              {
                  INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
                          EventDatabase.class, "event_database").
                          allowMainThreadQueries(). // SHOULD NOT BE USED IN PRODUCTION !!!
                          addCallback(sRoomDatabaseCallback).build();
              }
          }
      }
      return INSTANCE;
  }
  
  private static RoomDatabase.Callback sRoomDatabaseCallback = new RoomDatabase.Callback() {
      @Override
      public void onOpen (@NonNull SupportSQLiteDatabase db)
      {
          super.onOpen(db);
          new PopulateDbAsync(INSTANCE).execute();
      }
  };
  
  private static class PopulateDbAsync extends AsyncTask<Void, Void, Void>
  {
      private final EventDAO m_EventDao;
      private final PersonDAO m_PersonDao;
  
      PopulateDbAsync (EventDatabase db)
      {
          m_EventDao = db.eventDAO();
          m_PersonDao = db.personDAO();
      }
  
      @Override
      protected Void doInBackground (final Void... params)
      {
          Event event;
          m_EventDao.deleteAll();
          m_PersonDao.deleteAll();
  
          ... insert objects ...
          For example:
          Person person = new Person("Joe", "Bloe");
          m_PersonDao.insert(person);
  
          return null;
      }
  }
  

  }

  Extract from app gradle file dependencies:

  testImplementation 'junit:junit:4.12'
  androidTestImplementation 'com.android.support:support-annotations:27.1.1'
  androidTestImplementation 'com.android.support.test:runner:1.0.2'
  androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  
  // Lifecycle components
  def archLifecycleVersion = "1.1.0"
  implementation "android.arch.lifecycle:extensions:$archLifecycleVersion"
  annotationProcessor "android.arch.lifecycle:compiler:$archLifecycleVersion"
  implementation "android.arch.lifecycle:viewmodel:$archLifecycleVersion"
  implementation "android.arch.lifecycle:livedata:$archLifecycleVersion"
  
  // Room components
  def room_version = "1.1.1"
  implementation "android.arch.persistence.room:runtime:$room_version"
  annotationProcessor "android.arch.persistence.room:compiler:$room_version" // use kapt for Kotlin
  androidTestImplementation "android.arch.persistence.room:testing:$room_version"
  
• Gradle Project sync failed.Basic functionality not work properly

  How can I solve it?

  Here is the error

  Could not determine the class-path for interface  
  com.android.builder.model.AndroidProject.
  
• Usb Communication Android Phone to Android Things

  I am trying to setup USB communication serially with an Android phone to a Raspberry Pi loaded with Android Things (USB OTG cable).

  • I am using an OTG cable to connect to the Raspberry Pi, making my Android phone the Host
  • I understand how to use the Android USB Host API however it is the other side, that is, the code on the Android Things Raspberry Pi that I do not know what to do.

  What does the code on the Android Things Raspberry Pi have to be to receive and react to USB serial communication from the Host Android phone? If possible, can you give a code example of how to react to a read command then provide specific information (say just a simply a string) back to the phone.
• How can I get USB port information from user space

  I would like to get USB port information from user space . Suppose my mobile is connected to usb port of my laptop. I would like to get connected USB port information from user space.
• Sending raw text to printer via usb

  I am trying to send ZPL commands to a Zebra ZT230 printer. The printer and drivers are installed and the printer port is "USB003". The PC communicates perfectly with the printer via either Zebra Printer Setup Utilities or ZebraDesign. I tried the following code:

  Private Declare Function CreateFile Lib "kernel32.dll" (ByVal lpFileName As String, ByVal dwDesiredAccess As FileAccess, _
  ByVal dwShareMode As UInteger, ByVal lpSecurityAttributes As IntPtr, ByVal dwCreationDisposition As FileMode, _
  ByVal dwFlagsAndAttributes As UInteger, ByVal hTemplateFile As IntPtr) As System.Runtime.InteropServices.SafeHandle
  
      ' Command to be sent to the printer
      Dim command As String = "^XA^FO10,10,^AO,30,20^FDFDTesting^FS^FO10,30^BY3^BCN,100,Y,N,N^FDTesting^FS^XZ"
      ' Create a buffer with the command
      Dim buffer() As Byte = New Byte((command.Length) - 1) {}
      buffer = System.Text.Encoding.ASCII.GetBytes(command)
      ' Use the CreateFile external func to connect to the LPT1 port
      Dim printer As System.Runtime.InteropServices.SafeHandle = CreateFile("USB003:", FileAccess.ReadWrite, 0, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero)
      ' Aqui verifico se a impressora � v�lida
      If (printer.IsInvalid = true) Then
          Return
      End If
  
      ' Open the filestream to the lpt1 port and send the command
      Dim lpt1 As FileStream = New FileStream(printer, FileAccess.ReadWrite)
      lpt1.Write(buffer, 0, buffer.Length)
      ' Close the FileStream connection
      lpt1.Close 
  

  I get an error on this line: Dim printer As System.Runtime.InteropServices.SafeHandle = CreateFile("USB003:", FileAccess.ReadWrite, 0, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero)

  The error message and stack trace is:

  Cannot marshal 'return value': Returned SafeHandles cannot be abstract.

  at PerfectPotatoInventory.vb.PotatoGlobals.CreateFile(String& lpFileName, FileAccess dwDesiredAccess, UInt32 dwShareMode, IntPtr lpSecurityAttributes, FileMode dwCreationDisposition, UInt32 dwFlagsAndAttributes, IntPtr hTemplateFile) at PerfectPotatoInventory.vb.PotatoGlobals.PrintLabelsTest() in C:\Potatoes\PerfectPotatoInventory.vb\PerfectPotatoInventory.vb\PotatoGlobals.vb:line 798

  I am working in VB.net using VS2008 with target x86 and .Net 3.5.

  Please advise what I am doing wrong.