Handler post delay not work in for loop

Question

    Spannable WordtoSpan;
TextView tvView;
public void btnStart(View v)
{
    tvView = (TextView)findViewById(R.id.tvTest);
    changeColorOfText("I know just how to whisper, And I know just how to cry,I know just where to find the answers.");

}
int sIndexOfWord;
int fIndexOfWord;
private void changeColorOfText(String sentences)
{
    String[] arrWords = sentences.split(" ");
    WordtoSpan = new SpannableString(sentences);

    int k = 1;
    for(String word : arrWords) {

        sIndexOfWord = sentences.indexOf(word);
        fIndexOfWord = sIndexOfWord + word.length();
        Handler handler = new Handler();
        handler.postDelayed(new Runnable() { 
             public void run() { 
                WordtoSpan.setSpan(new BackgroundColorSpan(Color.YELLOW), sIndexOfWord, fIndexOfWord, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
                tvView.setText(WordtoSpan); 
             } 
        }, 2000*k++);
    }

}

This code not work, just color the last text of sentence. How can i color word one by one with handler.postDelayed method.

Thanks.

do you want the same color fo all of them when user clicks the word — Raghunandan, Apr 04 '13 at 07:32
I want to color each word by one after another on screen with 2 second transition time — oguz kilinc, Apr 04 '13 at 07:39

score 0 · Answer 1 · answered Apr 04 '13 at 07:51

may be you can try this: call setTextColor() method recursively at interval of 2 seconds

int k = 0;
private void setTxtColor(){
  if(k < arrWords.length){
      Handler handler = new Handler();
      handler.postDelayed(new Runnable() { 
           public void run() {
              sIndexOfWord = sentences.indexOf(arrWords[k]);
              fIndexOfWord = sIndexOfWord + word.length(); 
              WordtoSpan.setSpan(new BackgroundColorSpan(Color.YELLOW), sIndexOfWord, fIndexOfWord, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
              tvView.setText(WordtoSpan);
              k++;
              setTxtColor(); 
           } 
      }, 2000);
  }
}

because you are not waiting just for the handler completes it's task to colouring red the portion of your sentence in the for-each loop and as the iteration goes on and on and the handler scope is created and finished. only in the last iteration the handler will execute and completes it's task. — KunalK, Apr 04 '13 at 08:22

Raghunandan · Answer 2 · 2013-04-04T08:10:13.377

The below displays words with green color as the foregr0und for words every 1 second. Textview will have hello! displayed first with green color and after a delay for 1 second next word will be appended to the textview with green color. This repeats till it reaches the length of string s. If you don't want to append you just set text of the new word _tv.setText(text); and remove the append part.

Also i have used a timer and set the text on the ui thread. You can also use a handler.

String s;
int _count=0;//counter
Timer   _t;
TextView _tv;
String[] each;//holds each word in an array
Button b;
b= (Button) findViewById(R.id.button1);
_tv = (TextView) findViewById( R.id.tv );
b.setOnClickListener(new OnClickListener()
{

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub

        //s=et.getText().toString();
        s="hello!. how are you";
        _tv.setText("");
        for(int i=0;i<s.length();i++)
        {
            each = s.split("\\s+");
        }
     _t = new Timer();

        _t.scheduleAtFixedRate( new TimerTask() {
                @Override
                public void run() {


                    runOnUiThread(new Runnable() //run on ui thread
                     {
                      public void run() 
                      { 
                          if(_count<=each.length-1)
                          {
                          SpannableString text = new SpannableString(each[_count]);  

                        text.setSpan(new ForegroundColorSpan(Color.GREEN), 0,text.length(), 0);  
                        _tv.append(text);
                        _tv.append(" ");
                         System.out.println("................"+each[_count]);
                        _count=_count+1;


                     }
                          else
                          {
                              _t.cancel();
                          }
                      }

                     });
                }
            }, 1000, 1000 ); //change to 2000 for 2 second delay.

}

});

I will try but i want to know that in that code can i pause and play the coloring — oguz kilinc, Apr 04 '13 at 08:39
i din't understand what you mean by pause and play the coloring. — Raghunandan, Apr 04 '13 at 09:19

Handler post delay not work in for loop

2 Answers2

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