Question

I am trying to update a TextView at intervals of five seconds at a time after a button press, but when the application is run, the TextView will only display the last values of the loop that it is being run in.

Here is what I am trying:

private Runnable textUpdate = new Runnable() {
    public void run() {
        textOutput = (TextView)findViewById(R.id.textOutput);

        textOutput.setText("Reading Number " + (rIndex+1) + "\n");
        textOutput.append(sensorTime[rIndex] + "\n");
        textOutput.append("Value: " + rPoint.getValue() + "\n");
    }
};

…

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    mHandler = new Handler();

    TextView textOutput = (TextView) findViewById(R.id.textOutput);
    textOutput.setText("Simulation output:\n");

    Button button03 = (Button) findViewById(R.id.button03);
    button03.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            for(int i = 0; i < index; i++) {
                rIndex = i;
                rPoint = dp[i];

                mHandler.postDelayed(textUpdate, 5000);
            }
        }
    });

}

Cannot understand why only the last value of the information I am trying to output is being displayed in the TextView.

Any help is appreciated.

Answer 1

The issue I see is on your last line of code:

mHandler.postDelayed(textUpdate, 5000);

You’re posting all your updates at 5000 milliseconds, each starting milliseconds apart (as fast as the phone can loop).

Try this instead:

mHandler.postDelayed(textUpdate, i * 5000);