android - 如何使用 TimeTask 自动滑动 ViewPager 图像

Question

您好，我是 android 新手，在我的应用程序中，我的 ArrayList 中有很多图像 为什么我想在 Timetasker 的帮助下每 3 秒自动刷一次这些图像，这个过程需要不断重复，直到我们关闭应用程序。有人能帮帮我吗

MainActivity:-

public class MainActivity extends AppCompatActivity {

    ViewPager viewPager;

    Integer[] imageId = {R.drawable.image1, R.drawable.image2, R.drawable.image3, R.drawable.image4};
    String[] imagesName = {"image1","image2","image3","image4"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);

        viewPager = (ViewPager) findViewById(R.id.viewPager);
        PagerAdapter adapter = new CustomAdapter(MainActivity.this,imageId,imagesName);
        viewPager.setAdapter(adapter);
    }
}

自定义适配器:-

public class CustomAdapter extends PagerAdapter{

    private Activity activity;
    private Integer[] imagesArray;
    private String[] namesArray;

    public CustomAdapter(Activity activity,Integer[] imagesArray,String[] namesArray){

        this.activity = activity;
        this.imagesArray = imagesArray;
        this.namesArray = namesArray;
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {

        LayoutInflater inflater = ((Activity)activity).getLayoutInflater();

        View viewItem = inflater.inflate(R.layout.image_item, container, false);
        ImageView imageView = (ImageView) viewItem.findViewById(R.id.imageView);
        imageView.setImageResource(imagesArray[position]);
        TextView textView1 = (TextView) viewItem.findViewById(R.id.textview);
        textView1.setText(namesArray[position]);
        ((ViewPager)container).addView(viewItem);

        return viewItem;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return imagesArray.length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        // TODO Auto-generated method stub
        return view == ((View)object);
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        // TODO Auto-generated method stub
        ((ViewPager) container).removeView((View) object);
    }
}

Answer 1

您的问题已经回答 here

在你的 MainActivity.java 中添加这个

//...   
int currentPage = 0;
Timer timer;
final long DELAY_MS = 500;//delay in milliseconds before task is to be executed
final long PERIOD_MS = 3000; // time in milliseconds between successive task executions.


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_layout);

    viewPager = (ViewPager) findViewById(R.id.viewPager);
    PagerAdapter adapter = new CustomAdapter(MainActivity.this,imageId,imagesName);
    viewPager.setAdapter(adapter);

    /*After setting the adapter use the timer */
    final Handler handler = new Handler();
    final Runnable Update = new Runnable() {
        public void run() {
            if (currentPage == NUM_PAGES-1) {
                currentPage = 0;
            }
            viewPager.setCurrentItem(currentPage++, true);
         }
     };

    timer = new Timer(); // This will create a new Thread 
    timer.schedule(new TimerTask() { // task to be scheduled
        @Override
        public void run() {
            handler.post(Update);
        }
    }, DELAY_MS, PERIOD_MS);
}