Java 使用ViewPager或FragmentPagerAdapter查找显示的片段

我有一个扩展ActionBarActivity并实现ActionBar.TabListener的主活动

public class MainActivity extends ActionBarActivity implements ActionBar.TabListener {
SectionsPagerAdapter mSectionsPagerAdapter;
ViewPager mViewPager;
View mView;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    // Set up the action bar.
    final ActionBar actionBar = getSupportActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    // When swiping between different sections, select the corresponding
    // tab. We can also use ActionBar.Tab#select() to do this if we have
    // a reference to the Tab.
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            actionBar.setSelectedNavigationItem(position);
        }
    });

    // For each of the sections in the app, add a tab to the action bar.
    for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
        // Create a tab with text corresponding to the page title defined by
        // the adapter. Also specify this Activity object, which implements
        // the TabListener interface, as the callback (listener) for when
        // this tab is selected.
        actionBar.addTab(
                actionBar.newTab()
                        .setText(mSectionsPagerAdapter.getPageTitle(i))
                        .setTabListener(this));
    }
  }
}

但是，highScore值始终等于该值？ 感谢您的回答。谢谢你容忍我。

---

-Paul T.

您可以通过以下方式获得当前片段：

Fragment currentFragment = mSectionsPagerAdapter.getItem(mViewPager.getCurrentItem());

更新片段以获得分数：

Class CustomFragment extends Fragment{
    private TextView nView;
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        nView = view.findViewById(R.id.label);
    }

    public String getScore(){
        return nView.getText().toString();
    }
}

函数将如下所示：

public void goToHighScore(View view) {
    Intent intent = new Intent(this, DisplayScoreActivity.class);
    Fragment currentFragment = mSectionsPagerAdapter.getItem(mViewPager.getCurrentItem());
    String highScore = currentFragment.getScore();
    intent.putExtra(HIGH_SCORE, highScore);
    startActivity(intent);
}

但是，我建议您在片段中处理onClick事件，以提供更好的封装。按如下方式更新您的片段：

Class CustomFragment extends Fragment{
    private TextView nView;

    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        nView = view.findViewById(R.id.label);
        Button button = (Button)findViewByid(R.id.button)
        button.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                String highScore = nView.getText().toString()
                intent.putExtra(HIGH_SCORE, highScore);
                startActivity(intent);
            }
        });
    }
}

---

通过这样做，您的片段可以附加到不同的活动，而不会出现功能故障。

currentFragment无法调用findViewById方法，只能调用视图。感谢您的封装建议；我正在尝试。

Class CustomFragment extends Fragment{
    private TextView nView;

    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        nView = view.findViewById(R.id.label);
        Button button = (Button)findViewByid(R.id.button)
        button.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                String highScore = nView.getText().toString()
                intent.putExtra(HIGH_SCORE, highScore);
                startActivity(intent);
            }
        });
    }
}