Invalidate is not redrawing the screen. Android

Question

BufferedReader hl  = new BufferedReader(new InputStreamReader(getResources().openRawResource(R.raw.lines)));
                while(hl.ready()){
                    showL         


        

Answer 1

That is bacause your invalidate() is in a thread while loop and is being acummulated, so to speak, until the loop ends, and only than it draws...

I had the same problem when using Thread.sleep() within a loop. You can use a post delayed method to draw each line, which in this case is one line per second:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    BufferedReader hl  = new BufferedReader(new InputStreamReader(getResources().openRawResource(R.raw.text))); 
    TextView showLines = (TextView) findViewById(R.id.textView1);
    appendLines(hl, showLines);

}


public void appendLines(final BufferedReader br, final TextView tv){
    Handler handler = new Handler(); 
     handler.postDelayed(new Runnable() {           
         public void run() {                
             try {
                if(br.ready()){                     
                     try {
                        tv.append(br.readLine()+"\n");
                    } catch (IOException e) {
                        e.printStackTrace();
                    }                     
                     tv.invalidate();                     
                     appendLines(br, tv);             
                     }
            } catch (IOException e) {
                e.printStackTrace();
            } 
         }
         }, 1000); 
     }