如何在指定时间段内在TextView中显示一些文本？

Question

I have developed an android application which extracts single line text messages from the server. Once a button is clicked, it makes a function call which gets the next message from the server. Some of those messages are time based,

ie those messages have to be displayed in the TextView for a particular amount of time and after that time is elapsed, it should automatically make the function call to get the next message from the server(ie without the button being clicked).

Could someone please help me out in achieving this.

I tried using while loop as follows:

while(!presentTime.equals(expiryTime)){                 
    calculatePresentTym();   //This method calculates the presentTime value
    display.settext(the received instruction);
}

if(presentTime.equals(expiryTime))
    (make the function call)

If I do this, nothing is being displayed till presentTime and expiryTime are equal. Once they are equal, the next instruction is automatically fetched by the function call and is displayed in the TextView.

Answer 1

Use aa handler

Handler m_handler;
Runnable m_handlerTask ; 
m_handler = new Handler(); 
@Override
public void run() {
           // do something 
  m_handler.postDelayed(m_handlerTask, 1000);
 }
 };
 m_handlerTask.run(); 

T0 cancel the run

 m_handler.removeCallbacks(m_handlerTask);  // to cancel the run

You can also use a timer but you will have to use runOnUiThread to update ui since timer runs on a different thread.

Timer _t = new Timer();  
 _t.scheduleAtFixedRate( new TimerTask() {
        @Override
        public void run() {
          //do something
           runOnUiThread(new Runnable() //run on ui thread
             {
              public void run() 
              {      
                //update ui
              }
             });

        }
    }, 1000, 1000 ); 

Note:

gets the next message from the server

Getting the message from server should be done on a background thread.

Edit:

While copy pasting the initialization part was missing. You have a counter i that is displayed in the textview. The counter increases by 1 every second. When it reaches 100 you cancel the run. Modify the below according to your requirements.

 public class MainActivity extends Activity {

TextView tv;
Handler m_handler;
Runnable m_handlerTask ; 
int i=0;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv = (TextView) findViewById(R.id.textView1);
     m_handler = new Handler();
    m_handlerTask = new Runnable() {

        @Override
        public void run() {
            // TODO Auto-generated method stub
            if(i<=100)
            {
            tv.setText(""+i);
             i++;
            }
            else
            {
                m_handler.removeCallbacks(m_handlerTask);
            }
            m_handler.postDelayed(m_handlerTask, 1000);
        }
    };
    m_handlerTask.run();  
   }
   }  

Answer 2

Use a timer. Schedule the timer for repeated interval executions, and after each execution you can get the next text from the server and display the same.

Check the Timer reference scheduleAtFixedRate(TimerTask task, long delay, long period)