Hallo!
Ich habe eine ListView, die alle Audiodateien anzeigen soll. Problem: es wird gar nichts angezeigt (Liste ist leer).
Wo liegt der Fehler?
MainActivity.java
[Code=Java]
package musicplayer.ludevstudio.com.musikplayer;
import android.Manifest;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
public ArrayList<Song> songs;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
checkPermissions();
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_camera) {
// Handle the camera action
} else if (id == R.id.nav_gallery) {
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
// Check for permissions if there are granted or not
public boolean checkPermissions() {
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
searchAndShowSongs();
} else {
ActivityCompat.requestPermissions(this, new String[] { Manifest.permission.READ_EXTERNAL_STORAGE }, 1);
}
return false;
}
// React to Permissions Dialog
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] ergebnis) {
if (requestCode == 1) {
if (ergebnis.length > 0
&& ergebnis[0] == PackageManager.PERMISSION_GRANTED) {
} else {
}
return;
}
}
public void searchAndShowSongs() {
songs = new ArrayList<Song>();
ContentResolver musicResolver = getContentResolver();
Uri musicUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
Cursor songCursor = musicResolver.query(musicUri, null, null, null, null);
if(songCursor==null && songCursor.moveToFirst()) {
int titlelColumn = songCursor.getColumnIndex(MediaStore.Audio.Media.TITLE);
do {
String thisTitle = songCursor.getString(titlelColumn);
songs.add(new Song(thisTitle));
} while (songCursor.moveToNext());
songs.add(new Song("Fail of Searching"));
}
SongAdapter liedAdapter = new SongAdapter(this, songs);
ListView liedListView = (ListView)findViewById(R.id.SongListView);
liedListView.setAdapter(liedAdapter);
Toast.makeText(this, "Test", Toast.LENGTH_SHORT).show();
}
}
[/Code]
SongAdapter.Java (Der ListAdapter)
[Code=Java]
package musicplayer.ludevstudio.com.musikplayer;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.RelativeLayout;
import android.widget.TextView;
import java.util.ArrayList;
public class SongAdapter extends BaseAdapter {
private ArrayList<Song> songs;
private LayoutInflater liedInf;
public SongAdapter(Context c, ArrayList<Song> songs){
this.songs = songs;
liedInf = LayoutInflater.from(c);
}
@Override
public int getCount() {
return songs.size();
}
@Override
public Object getItem(int arg0) {
return null;
}
@Override
public long getItemId(int arg0) {
return arg0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
RelativeLayout songLay = (RelativeLayout)liedInf.inflate(R.layout.songlistview_entrees, arg2, false);
TextView songView = (TextView)songLay.findViewById(R.id.LiedTitel);
Song momentanesLied = songs.get(arg0);
songView.setText(momentanesLied.getTitel());
songLay.setTag(arg0);
return songLay;
}
}
[/Code]
Song.java
[Code=Java]
package musicplayer.ludevstudio.com.musikplayer;
public class Song {
private String titel = "";
public Song(String title) {
this.titel = title;
}
public String getTitel() {
return titel;
}
public void setTitel(String titel) {
this.titel = titel;
}
}
[/Code]
activity_main.xml
[Code=XML]
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer" />
</android.support.v4.widget.DrawerLayout>
[/Code]
content_main.xml
[Code=XML]
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/SongListView"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:visibility="visible"
android:layout_alignParentStart="true" />
</RelativeLayout>
[/Code]
app_bar_main.xml
[Code=XML]
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_main" />
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="@dimen/fab_margin"
app:srcCompat="@android:drawable/ic_dialog_email" />
<include
layout="@layout/content_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="top"
/>
</android.support.design.widget.CoordinatorLayout>
[/Code]
songlistview_entrees.xml
[Code=xml]
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Medium Text"
android:id="@+id/LiedTitel"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
[/Code]
