CODEWITHSUNDEEP
javaandroidmultithreadingtime
vnshetty
vnshetty

Reputation: 20132

Display charecters in textview with time delay - android

I want to display letters using textview. and the letter should display in textview after some time interval.

i used following code....

String a="Apple";
String b="";
.......
.......


public void run() {

    for (int i = 0; i < 5; i++) {
        b=b+""+a.charAt(i);
        mTextView.setText(b); //Problem here
        Log.d("Letters",""+b);
            try {
                  sleep(2000); 
           } catch (InterruptedException e) {}
    }

Log cat Result: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
Any Solution?

Upvotes: 2

Views: 1245

Answers (2)

inazaruk
inazaruk

Reputation: 74790

You can not change UI controls from other threads. Update your code in a next way:

public void run() {

    for (int i = 0; i < 5; i++) {
        b=b+""+a.charAt(i);

        //one of the ways to update UI controls from non-UI thread.
        runOnUiThread(new Runnable()
        {               
            @Override
            public void run()
            {
                mTextView.setText(b); //no problems here :)                 
            }
        });

        Log.d("Letters",""+b);
            try {
                  sleep(2000); 
           } catch (InterruptedException e) {}
    }
}

Upvotes: 2

Kakey
Kakey

Reputation: 4024

You cannot update the textview in the thread since UI updation is not Thread safe.

use this

    public void run() {

        for (int i = 0; i < 5; i++) {
            b=b+""+a.charAt(i);

            Log.d("Letters",""+b);
                try {
                      sleep(2000); 
                      handler.post(updateMessgae)
               } catch (InterruptedException e) {}
        }

private final Runnable updateMessgae= new Runnable() 
    {
        public void run() 
        {
            try 
            {
            Log.d("Letters",""+b);  
            } 
            catch (Exception e) 
            {
                e.printStackTrace();
            }
        }
    };
    private final Handler handler = new Handler();

Upvotes: 2

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