EDIT Frohes neues Jahr! Um genau zu sein, habe ich eine einfache Musik-App in Android Studio erstellt, die MP3-Dateien aus meinem internen Speicher liest. Alles gut, bis ich beschließe, ein zufälliges Bild auf jeden einzelnen Track auf der Liste zu setzen. (Vor dem Namen des Songs möchte ich ein Bild anzeigen.) Wenn ich ein einzelnes Bild in 'src' unter ImageView anwähle, funktioniert es und erscheint allen Songs. Ich werde einen Teil meiner Code Atach unter: Hauptaktivität:Meine App gestoppt jedes Mal, wenn ich es laden
package com.alg.amzar.spectrum;
import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
static {
System.loadLibrary("native-lib");
}
private ArrayList<Song> songList;
private ListView songView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
schimbare();
songView = (ListView)findViewById(R.id.song_list);
songList = new ArrayList<Song>();
getSongList();
Collections.sort(songList, new Comparator<Song>(){
public int compare(Song a, Song b){
return a.getTitle().compareTo(b.getTitle());
}
});
SongAdapter songAdt = new SongAdapter(this, songList);
songView.setAdapter(songAdt);
}
public void schimbare() {
int[] photos={R.drawable.img_0, R.drawable.img_1,R.drawable.img_2};
ImageView image = (ImageView) findViewById(R.id.imagine);
Random ran=new Random();
int i=ran.nextInt(photos.length);
image.setImageResource(photos[i]);
}
public void getSongList() {
ContentResolver musicResolver = getContentResolver();
Uri musicUri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
Cursor musicCursor = musicResolver.query(musicUri, null, null, null, null);
if(musicCursor!=null && musicCursor.moveToFirst()){
//get columns
int titleColumn = musicCursor.getColumnIndex
(android.provider.MediaStore.Audio.Media.TITLE);
int idColumn = musicCursor.getColumnIndex
(android.provider.MediaStore.Audio.Media._ID);
//add songs to list
do {
long thisId = musicCursor.getLong(idColumn);
String thisTitle = musicCursor.getString(titleColumn);
songList.add(new Song(thisId, thisTitle));
}
while (musicCursor.moveToNext());
}
}
public native String stringFromJNI();
}
Aktivität Haupt .xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="#FF330000"
tools:context=".MainActivity" >
<ListView
android:id="@+id/song_list"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
Song.xml:
<LinearLayout 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="fill_parent"
android:layout_height="wrap_content"
android:onClick="songPicked"
android:orientation="vertical"
android:padding="5dp" >
<ImageView
android:layout_width="70dp"
android:id="@+id/imagine"
android:layout_height="50dp" />
<TextView
android:id="@+id/song_title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#FFFFFF99"
android:textSize="15sp"
android:textStyle="bold"
android:layout_marginBottom="20dp"
android:layout_marginLeft="75dp"
android:layout_marginTop="-42dp"/>
</LinearLayout>
Neben diesem, ich habe 2 mehr Java-Klassen. Ich denke, das Problem hier ist, aber idk, was falsch ist:
public void schimbare() {
int[] photos={R.drawable.img_0, R.drawable.img_1,R.drawable.img_2};
ImageView image = (ImageView) findViewById(R.id.imagine);
Random ran=new Random();
int i=ran.nextInt(photos.length);
image.setImageResource(photos[i]);
}
Eine andere fragen, von mir ist, was ‚veraltet‘ ist, wenn I .getDrawable verwenden. Vielen Dank im Voraus!
Logcat:
ime: FATAL EXCEPTION: main
Process: com.alg.amzar.spectrum, PID: 28677
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.alg.amzar.spectrum/com.alg.amzar.spectrum.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2381)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2433)
at android.app.ActivityThread.access$800(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1346)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5341)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:830)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:646)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.alg.amzar.spectrum.MainActivity.schimbare(MainActivity.java:57)
at com.alg.amzar.spectrum.MainActivity.onCreate(MainActivity.java:31)
at android.app.Activity.performCreate(Activity.java:5343)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2335)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2433)
at android.app.ActivityThread.access$800(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1346)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5341)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:830)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:646)
at dalvik.system.NativeStart.main(Native Method)
Mein Handy Android-Version: 4.4.2 (API 19) Ziel SDK Version: "19" MinSDK Version: "14"
SongAdapter.java:
package com.alg.amzar.spectrum;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.ArrayList;
public class SongAdapter extends BaseAdapter {
private ArrayList<Song> songs;
private LayoutInflater songInf;
public SongAdapter(Context c, ArrayList<Song> theSongs) {
songs = theSongs;
songInf = LayoutInflater.from(c);
}
@Override
public int getCount() {
return songs.size();
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//map to song layout
LinearLayout songLay = (LinearLayout)songInf.inflate
(R.layout.song, parent, false);
//get title and artist views
TextView songView = (TextView)songLay.findViewById(R.id.song_title);
//get song using position
Song currSong = songs.get(position);
//get title and artist strings
songView.setText(currSong.getTitle());
//set position as tag
songLay.setTag(position);
return songLay;
}
}
Bitte beachten Sie auch Android-Version Ihres Telefons geben Sie mit und gezielte Version Ihrer Anwendung –
sind Testen Sie sollten Ihre Anwendung debuggen, gehen Zeile für Zeile und sehen, wo Problem. – avinesh