Please help me . I am getting Null pointer Exception with the below code

Question

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The following code takes the songlist from SD card or phone and display in the Mp3 Player. But when i run the app , app fails and shows null pointer exception in the following code.

Can some one please help me to resolve this issue. Please

public class SongsManager {
    // SDCard Path
    final String MEDIA_PATH = new String("");
    private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

    // Constructor
    public SongsManager(){

    }

    /**
     * Function to read all mp3 files from sdcard
     * and store the details in ArrayList
     * */
    public ArrayList<HashMap<String, String>> getPlayList(){
        File home = new File(MEDIA_PATH);

        if (home.listFiles(new FileExtensionFilter()).length > 0) {
            for (File file : home.listFiles(new FileExtensionFilter())) {
                HashMap<String, String> song = new HashMap<String, String>();
                song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
                song.put("songPath", file.getPath());

                //Adding each song to SongList
                songsList.add(song);
            }
        }
        // return songs list array
        return songsList;
    }

    /**
     * Class to filter files which are having .mp3 extension
     * */
    class FileExtensionFilter implements FilenameFilter {
        public boolean accept(File dir, String name) {
            return (name.endsWith(".mp3") || name.endsWith(".MP3"));
        }
    }
}

Log Cat File

Unable to start activity ComponentInfo{com.android.musicplayer/com.android.musicplayer.AndroidBuildingMusicPlayerActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2247)
at android.app.ActivityThread.access$800(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5050)
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:806)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.android.musicplayer.SongsManager.getPlayList(SongsManager.java:25)
at com.android.musicplayer.AndroidBuildingMusicPlayerActivity.onCreate(AndroidBuildingMusicPlayerActivity.java:77)
at android.app.Activity.performCreate(Activity.java:5248)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2247)
at android.app.ActivityThread.access$800(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5050)
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:806)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
at dalvik.system.NativeStart.main(Native Method)

Posted 23-Jun-15 8:28am

SHASHANK Balaganchi

Updated 23-Jun-15 8:50am

v2

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Comments

Sergey Alexandrovich Kryukov 23-Jun-15 15:31pm

In what line? The combination of the code and exception stack doesn't show it. Why won't you comment appropriate line(s) in code and refer to these comments in your explanatory text?
Such exceptions are the easiest to locate and to fix the related problem. Just use the debugger.
—SA

Richard MacCutchan 24-Jun-15 3:16am

Your MEDIA_PATH does not point anywhere, so you probably did not get any files. However, the actual error may have occurred earlier.

[no name] 24-Jun-15 9:03am

The Exception is coming in the below line

if (home.listFiles(new FileExtensionFilter()).length > 0) {
for (File file : home.listFiles(new FileExtensionFilter())) {
HashMap<string, string=""> song = new HashMap<string, string="">();
song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
song.put("songPath", file.getPath());

//Adding each song to SongList
songsList.add(song);

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