CODEWITHSUNDEEP
androidprogress-bar
user2160008
user2160008

Reputation: 379

Progress bar give NullPointerException

I have two class. class A is activity where my progress bar will be use. and class B is no-activity where my progress bar will be update. but when i calling progress bar from non-activity class B . i got null pointer exception.

class A:-

ProgressBar progressBar; 
 @Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);
progressBar = (ProgressBar) findViewById(R.id.progressBar1);}

class B:-

 new Thread(new Runnable() {

             int i = 0;
             int progressStatus = 0;

             public void run() {
                 while (progressStatus < 100) {
                     progressStatus += doWork();
                     try {
                         Thread.sleep(500);
                     } catch (InterruptedException e) {
                         e.printStackTrace();
                     }

                     // Update the progress bar
                     ((Activity) cnt).runOnUiThread(new Runnable() {

                         public void run() {
                            XMPPClient xc = new XMPPClient();
                            xc.progressBar = new ProgressBar(cnt);
                            xc.progressBar.setProgress(progressStatus);
                        //  Toast.makeText(cnt, "ok", Toast.LENGTH_SHORT).show();
                             i++;
                         }
                     });
                 }
             }
             private int doWork() {

                 return i * 3;
              }
        }).start();

when i added this line :-  xc.progressBar = new ProgressBar(cnt);
then i did not get nullpointerexception. But now my progress bar is **not updating.**

please any one help me.

Upvotes: 1

Views: 1577

Answers (2)

abhi
abhi

Reputation: 759

in ClassA :- 

  ProgressBar progressBar; 
         @Override
        public void onCreate(Bundle icicle) {
            super.onCreate(icicle);
            setContentView(R.layout.main);
        progressBar = (ProgressBar) findViewById(R.id.progressBar1);


       ////Then Use the Reference on Progressbar 

       ClassB classb = new ClassB(this, progressBar);
    }

Then in ClassB :- 

public class ClassB{

    private Context cnt;
    private ProgressBar progressBar;

    public ClassB(Context context, ProgressBar pBar){
         cnt = context;
         progressBar = pBar;

 new Thread(new Runnable() {

             int i = 0;
             int progressStatus = 0;

             public void run() {
                 while (progressStatus < 100) {
                     progressStatus += doWork();
                     try {
                         Thread.sleep(500);
                     } catch (InterruptedException e) {
                         e.printStackTrace();
                     }

                     // Update the progress bar
                     ((Activity) cnt).runOnUiThread(new Runnable() {

                         public void run() {
                            XMPPClient xc = new XMPPClient();
                            xc.progressBar = new ProgressBar(cnt);
                            xc.progressBar.setProgress(progressStatus);
                        //  Toast.makeText(cnt, "ok", Toast.LENGTH_SHORT).show();
                             i++;
                         }
                     });
                 }
             }
             private int doWork() {

                 return i * 3;
              }
        }).start();


    }

Upvotes: 0

Carnal
Carnal

Reputation: 22064

ProgressBar progressBar; 

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);
    progressBar = (ProgressBar) findViewById(R.id.progressBar1);

    ClassB classb = new ClassB(this, progressBar);
}

public class ClassB{

    private Context cnt;
    private ProgressBar progressBar;

    public ClassB(Context context, ProgressBar pBar){
         cnt = context;
         progressBar = pBar;
    }
}

Now you can use progressBar instead of creating a new one like you did in previous code! Just a quick overview...

Upvotes: 4

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