Question

i have a question regarding the refreshment of an imageview. Basically, I have a button and a dice. I want the dice to rotate a couple of times (to simulate a dice roll) – 0.5 sec, and finally to stop it. The problem is: I can just see the final result. The dice roll simulation is being done, but the change is not being shown (the imageview is not being refreshed). I think it’s my erroreneous understanding of the way this should be implemented.

I isolated the problem in a simple project, a couple of lines of code, you can download it here (in case you have the time to play with it): http://dl.dropbox.com/u/26268461/vrtiKocku_eng.rar

The whole code looks like this:

---

package com.viscode.vrtiKocku;

import java.util.Random;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class VrtiKockuActivity extends Activity {
    /** Called when the activity is first created. */

    private final Handler mHandler = new Handler(); 
    Random randomGenerator = new Random();          
    private ImageView dice1;                        

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

        dice1 = (ImageView)findViewById(R.id.imageView1);   
        mHandler.post(mRollDice);                               
    }

private final Runnable mRollDice = new Runnable() {

    public void run() {
        Button buttonRollDice = (Button) findViewById(R.id.buttonRollDice); 
        buttonRollDice.setOnClickListener(new View.OnClickListener() {      

            public void onClick(View v) {                               
                Integer rand, rollSimulationTimeLimit = 500, rollDuration = 100;;                               

                //simulate dice roll for 500 ms, by 5 rolls at 100 ms
                while (rollDuration < rollSimulationTimeLimit) { 
                    rand = randomGenerator.nextInt(6) + 1;
                    postaviKocku(rand, dice1);

                //  wait and SHOW the simulated roll for 100 ms = rollDuration
                try {
                    Thread.sleep(rollDuration);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                rollDuration += rollDuration;
                }                                               
            }
        }); 
    }
};


//this procedure sets the imageview to the proper image, based on the rolled number
private void postaviKocku(Integer rand, final ImageView dice) {
    switch (rand) {
    case 1:
            dice.setImageDrawable(getResources().getDrawable(R.drawable.one_red));                      
        break;
    case 2:
            dice.setImageDrawable(getResources().getDrawable(R.drawable.two_red));                      
        break;
    case 3:
            dice.setImageDrawable(getResources().getDrawable(R.drawable.three_red));                        
        break;
    case 4:
            dice.setImageDrawable(getResources().getDrawable(R.drawable.four_red));                     
        break;
    case 5:
            dice.setImageDrawable(getResources().getDrawable(R.drawable.five_red));                     
        break;
    case 6:
            dice.setImageDrawable(getResources().getDrawable(R.drawable.six_red));                      
        break;
    default:
        break;
    }
}


}

---

Answer 1

use Handler’s postDelayed instead of Threads..

  package com.viscode.vrtiKocku;

import java.util.Random;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class VrtiKockuActivity extends Activity {
    /** Called when the activity is first created. */

    private final Handler mHandler = new Handler(); // handler
    Random randomGenerator = new Random(); // varijabla tipa random
    Boolean kocka1pritisnuta = false; // da li je kocka zakljucana ili ne
    Integer vkocka1; // drzi vrijednost kocke
    private ImageView kocka1; // varijabla imageview-a

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

        kocka1 = (ImageView) findViewById(R.id.imageView1); // inicijalizira
                                                            // imageview
        mHandler.post(mBacaj); // pokrece handler
    }

    private final Runnable mBacaj = new Runnable() {

        public void run() {
            Button buttonBacaj = (Button) findViewById(R.id.buttonBacaj); // veze
                                                                            // button
                                                                            // za
                                                                            // varijablu
            buttonBacaj.setOnClickListener(new View.OnClickListener() { // postavlja
                                                                        // listener
                                                                        // na
                                                                        // dugme

                        public void onClick(View v) { // definise click event
                            // TODO Auto-generated method stub
                            Integer rand; // varijabla koja drzi rand broj
                            vrtiKocke(); // pokreni VRCENJE KOCKI

                            if (!kocka1pritisnuta) { // ako kocka nije
                                                        // zakljucana...
                                rand = randomGenerator.nextInt(6) + 1; // generisi
                                                                        // random
                                                                        // broj
                                vkocka1 = rand; // zapamti vrijednost da mozes
                                                // racunat poslije
                                postaviKocku(rand, kocka1,0); // postavi sliku
                                                            // kocke koja
                                                            // odgovara
                                                            // vrijednosti
                            }
                        }
                    });

            final ImageView kocka1 = (ImageView) findViewById(R.id.imageView1); // povezi
                                                                                // imageview
                                                                                // sa
                                                                                // kockom
            kocka1.setOnClickListener(new View.OnClickListener() { // postavi
                                                                    // listener
                                                                    // na kocku
                public void onClick(View v) { // definisi click event za kocku
                    kocka1pritisnuta = pritisniKocku(kocka1pritisnuta, kocka1); // izvrsi
                                                                                // click
                                                                                // event
                                                                                // za
                                                                                // kocku
                }
            });
        }
    };

    // ova procedura treba da vrti kocke do 500 milisekundi, trajanje je po 100
    // ms, znaci 5x se trabaju okrenuti
    private void vrtiKocke() {
        Integer rand, limit = 1000, trajanje = 200;
        while (trajanje < limit) {
            if (!kocka1pritisnuta) {
                rand = randomGenerator.nextInt(6) + 1;
                postaviKocku(rand, kocka1, trajanje);
            }

            rand = randomGenerator.nextInt(100);
            // cekaj vrijeme trajanja

            trajanje += trajanje;
        }
    }

    // ova procedura postavlja vrijednost kocke na onu vrijednost broja koji je
    // dobiven
    private void postaviKocku(final Integer rand, final ImageView kocka, Integer trajanje) {
        //Log.i("kocka", rand+"");
        switch (rand) {
        case 1:
            mHandler.postDelayed(new Runnable() {
                public void run() {
                    Log.i("kocka", rand+"");
                    kocka.setImageDrawable(getResources().getDrawable(R.drawable.one_red));
                }
            }, trajanje);
            break;
        case 2:
            mHandler.postDelayed(new Runnable() {
                public void run() {
                    Log.i("kocka", rand+"");
                    kocka.setImageDrawable(getResources().getDrawable(R.drawable.two_red));
                }
            }, trajanje);
            break;
        case 3:
            mHandler.postDelayed(new Runnable() {
                public void run() {
                    Log.i("kocka", rand+"");
                    kocka.setImageDrawable(getResources().getDrawable(R.drawable.three_red));
                }
            }, trajanje);
            break;
        case 4:
            mHandler.postDelayed(new Runnable() {
                public void run() {
                    Log.i("kocka", rand+"");
                    kocka.setImageDrawable(getResources().getDrawable(R.drawable.four_red));
                }
            }, trajanje);
            break;
        case 5:
            mHandler.postDelayed(new Runnable() {
                public void run() {
                    Log.i("kocka", rand+"");
                    kocka.setImageDrawable(getResources().getDrawable(R.drawable.five_red));
                }
            }, trajanje);
            break;
        case 6:
            mHandler.postDelayed(new Runnable() {
                public void run() {
                    Log.i("kocka", rand+"");
                    kocka.setImageDrawable(getResources().getDrawable(R.drawable.six_red));
                }
            }, trajanje);
            break;
        default:
            break;
        }
    }

    // ova procedura samo zakljucava ili otkljucava kocku
    private boolean pritisniKocku(boolean kockapritisnuta, ImageView kocka) {
        if (!kockapritisnuta) {
            kocka.setAlpha(128);
        } else
            kocka.setAlpha(255);
        return !kockapritisnuta;
    }

}