java - 在 fragment 之间滑动时如何显示进度？

Question

我有一个带有寻呼机适配器的 Activity ，其中包含一些 fragment 。我还在 Activity 顶部创建了一个进度条(水平)。我需要在浏览 fragment 时栏会显示进度。例如，当我在第一个 fragment 中时它应该是灰色的，然后当我滑动 fragment 时它会逐渐变大，而当我在最后一个 fragment 中时它应该是全绿色。

ma​​inActivity.java

public class testActivity extends FragmentActivity {

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

    private  void initialisePaging() {
        List<Fragment> fragments = new Vector<Fragment>();
        fragments.add(Fragment.instantiate(this,fragment1.class.getName()));
        fragments.add(Fragment.instantiate(this,fragment2.class.getName()));
        fragments.add(Fragment.instantiate(this,fragment3.class.getName()));
        PagerAdapter mPagerAdapter = new PagerAdapter(this.getSupportFragmentManager(), fragments);

        ViewPager pager = (ViewPager) findViewById(R.id.viewpager);
        pager.setAdapter(mPagerAdapter);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_test, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

}

PagerAdapter.java

public class PagerAdapter extends FragmentPagerAdapter {

    private List<Fragment> fragments;

    public PagerAdapter(FragmentManager fm, List<Fragment> fragments) {
        super(fm);
        this.fragments = fragments;
    }

    @Override
    public Fragment getItem(int arg0) {
        return this.fragments.get(arg0);
    }

    @Override
    public int getCount() {
        return this.fragments.size();
    }

    public void setFragments(List<Fragment> fragments) {
        this.fragments = fragments;
    }
}

Answer 1

其实我找到了一个非常简单的答案。这就是我所做的:

  pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

        @Override
        public void onPageScrollStateChanged(int arg0) {

        }

        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {

        }

        @Override
        public void onPageSelected(int pos) {
          //This is because progress is 0 at the start of the program
          progress++;
          ProgressBar progress = (ProgressBar) findViewById(R.id.progressBar);
                progress.setProgress(position++);
        }

    });