Question

I’ve had this really annoying problem for a couple of days, and I cannot quite seem to solve it. I am trying to open a .csv file, so I imported it into the res/raw/ folder of my project. Then I am trying to open and read it via the getResources() method, and that’s exactly where I get the NullPointerException. Here’s the method that reads the file and fills an array with the available lines.

Here’s my Activity where I create an Object newwords from the class Words, and then I want to call the PlayWithRawFiles() method from class Words.

public class Swear_Activity extends Activity implements OnInitListener, OnClickListener {

    private Words newwords;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_swear);
    }
    public void onClick(View view){
        try {
            newwords.PlayWithRawFiles();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            System.out.println("greshka");
            e.printStackTrace();
        }
    }
}

now this is the class where i get the error

public class Words{

    public Word[] wordsArray;
    private String locale = "de";
    
    public Words(String locale) {
        if (locale != null ) {
            this.locale = locale;
        }
    }
    
    Context c;
    public void PlayWithRawFiles() throws IOException  {
        String str="";
        StringBuffer buf = new StringBuffer();          
        int i = 0;
        InputStream is = c.getResources().openRawResource(R.raw.est);
        BufferedReader reader = null;
        try{
            if (is != null) reader = new BufferedReader(new InputStreamReader(is));
        }
        catch(Exception e) {
            System.out.println ("ss");
            e.printStackTrace();
        }
            
        if (is!=null) {                         
            while ((str = reader.readLine()) != null) { 
                Word wd = new Word(1,"str");
                this.wordsArray[i] = wd;
                i++;
            }               
        }       
        is.close();
    }
}

here is class Word

public class Word {
    private int type;
    private String data;

    public Word(int type, String data){
        this.type = type;
        this.data=data;
    }

    public int getType(){
        return this.type;
    }
    public String getData(){
        return this.data;
    }
}

Here is the Stack Trace

07-10 13:28:58.558: E/AndroidRuntime(647): FATAL EXCEPTION: main

07-10 13:28:58.558: E/AndroidRuntime(647): java.lang.NullPointerException

07-10 13:28:58.558: E/AndroidRuntime(647): at de.android.swearapp.Swear_Activity.onClick(Swear_Activity.java:32)

07-10 13:28:58.558: E/AndroidRuntime(647): at >android.view.View.performClick(View.java:2408)

07-10 13:28:58.558: E/AndroidRuntime(647): at android.view.View$PerformClick.run(View.java:8816)

07-10 13:28:58.558: E/AndroidRuntime(647): at android.os.Handler.handleCallback(Handler.java:587)

07-10 13:28:58.558: E/AndroidRuntime(647): at android.os.Handler.dispatchMessage(Handler.java:92)

07-10 13:28:58.558: E/AndroidRuntime(647): at android.os.Looper.loop(Looper.java:123)

07-10 13:28:58.558: E/AndroidRuntime(647): at android.app.ActivityThread.main(ActivityThread.java:4627)

07-10 13:28:58.558: E/AndroidRuntime(647): at java.lang.reflect.Method.invokeNative(Native Method)

07-10 13:28:58.558: E/AndroidRuntime(647): at java.lang.reflect.Method.invoke(Method.java:521)

07-10 13:28:58.558: E/AndroidRuntime(647): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)

07-10 13:28:58.558: E/AndroidRuntime(647): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)

07-10 13:28:58.558: E/AndroidRuntime(647): at dalvik.system.NativeStart.main(Native Method)

What have I done wrong? I’m really stuck at this one. Thank you in advance!

Answer 1

Two things I see here,

• You are not instantiating newwords as in newwords = new Words("");
• c is null and not assigned a context.

I recommend you re-code the class like this:

public class Words{
   public Word[] wordsArray;
   private String locale = "de";
   private Context c;
   public Words(String locale, Context paramContext) {
      if (locale != null ) {
         this.locale = locale;
      }
      c = paramContext;
   }
// Rest of code ok.
//
// Remove the Context c variable further on as it is declared above!
}

What is done is, we simply added the Context as part of the constructor for the class Words. Then to instantiate the class Words do this, from your SwearActivity class:

public void onClick(View view){
    newwords = new Words("", getApplicationContext());
    try {
        newwords.PlayWithRawFiles();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        System.out.println("greshka");
        e.printStackTrace();
    }
}