Showing ArrayList Contents in ListView

Question

I'm facing a problem in showing ArrayList in ListView in android.I'm getting a null pointer exception when try to load array List in ListView. Actually I'm trying to load Memory cards contents in android List View.(Showing Specific Folders Contents).I'm new to Android Development,please help.

public class Access_MemCardActivity_main extends Activity{

Button btn_view;
boolean mExternalMediaAvailable=false;
ArrayList<String> item=new ArrayList<String>();

ArrayAdapter<String> adapter;
private ListView lv;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    String state=Environment.getExternalStorageState();

    if(Environment.MEDIA_MOUNTED.equals(state)){
        mExternalMediaAvailable=true;
    }
    else{
        mExternalMediaAvailable=false;
    }

    btn_view=(Button)findViewById(R.id.btn_view);

   btn_view.setOnClickListener(new OnClickListener() {

    public void onClick(View v) {
        // TODO Auto-generated method stub
        if(mExternalMediaAvailable){
            Toast.makeText(getApplicationContext(), "External Media..", Toast.LENGTH_LONG).show();

            //getDir(Environment.getExternalStorageDirectory().toString());
            //Intent i = new Intent(Intent.ACTION_VIEW);
        String SD_Card_Path=Environment.getExternalStorageDirectory().toString();

            //String SD_Card="/sdcard/reports";
            File file = new File(SD_Card_Path);
            File[] file_Array=file.listFiles();

            Toast.makeText(getApplicationContext(), file_Array.toString(), Toast.LENGTH_LONG).show();

            lv=(ListView)findViewById(R.id.list_view);

            for(int i=0;i< file_Array.length;i++){
                 file=file_Array[i];
                 if(file.isDirectory()){
                     Log.d("Directory","Added...");
                     item.add(file.getName()+"/");
                 }
                 else{
                     Log.d("File","Added...");
                     item.add(file.getName());
                 }
            }
            Log.d("adapter", "Before...");
            ArrayAdapter<String> adapter=new ArrayAdapter<String>(Access_MemCardActivity_main.this,android.R.layout.simple_list_item_1,item);
            lv.setAdapter(adapter);
            Log.d("set_adapter", "After...");
            Toast.makeText(getApplicationContext(), adapter.toString(),Toast.LENGTH_LONG).show();
        }
        else{
            Toast.makeText(getApplicationContext(), "You Dont Have External Media..", Toast.LENGTH_LONG).show();
        }
    }
});        
}

}

on which line you are getting `NPE` line number and the code at that line — Mohsin Naeem, Dec 03 '12 at 07:15
Go to LogCat, and paste the stack trace of the NullPointerException. — Matthew Quiros, Dec 03 '12 at 07:18
Before setting **adapter** to your **ListView** check whether the arraylist contains items or not by printing the **size** of **arraylist** in **Log** — NARESH REDDY, Dec 05 '12 at 11:09
Before setting adapter to your ListView check whether the arraylist contains items or not by printing the size of arraylist in Log — NARESH REDDY, Dec 05 '12 at 11:09

score 1 · Answer 1 · answered Dec 05 '12 at 11:08

1

Before setting adapter to your ListView check whether the arraylist contains items or not by printing the size of arraylist in Log

answered Dec 05 '12 at 11:08

NARESH REDDY

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Showing ArrayList Contents in ListView

1 Answers1