如何在带有更多片段的操作栏上添加后退按钮

Question

知道如何在我的操作栏上添加一个后退按钮吗？这里是my acplication，我想在 INFO 按钮之前添加它。 我尝试为操作栏添加该代码，但它不起作用：

  actionBar.setDisplayShowTitleEnabled(false);
  actionBar.setHomeButtonEnabled(true);

这是我的活动：

public class TrailActivity extends FragmentActivity implements ActionBar.TabListener {

SectionsPagerAdapter mSectionsPagerAdapter;
ViewPager mViewPager;
Intent intent;
Trail trail;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    intent = getIntent();
    setContentView(R.layout.trail_fracment_main);


    trail = intent.getParcelableExtra("trail");
    final ActionBar actionBar = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    actionBar.setDisplayShowTitleEnabled(false);
    actionBar.setHomeButtonEnabled(true);
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            actionBar.setSelectedNavigationItem(position);
        }
    });
    for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
        actionBar.addTab(actionBar.newTab().setText(mSectionsPagerAdapter.getPageTitle(i)).setTabListener(this));
    }
}

@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, tell the ViewPager to switch to the corresponding page.
    mViewPager.setCurrentItem(tab.getPosition());
}

@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}

@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        if (position == 0) {
            InfoFragments infoFragments = new InfoFragments();
            infoFragments.setTrail(trail);
            Fragment fragment = infoFragments;
            return fragment;
        } else if (position == 1) {
            return new MapFragments();

        } else {
            return new WondersFragments();
        }

    }

    @Override
    public int getCount() {
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase(l);
            case 1:
                return getString(R.string.title_section2).toUpperCase(l);
            case 2:
                return getString(R.string.title_section3).toUpperCase(l);
        }
        return null;
    }
}

}

编辑： 在左侧，它应该是如何使用后退按钮来查看我的操作栏，而在右侧，它实际上是我现在的应用程序。所以..我怎样才能让它看起来像左边的应用程序？

如果有人知道，请告诉我我该怎么做。

谢谢：D

Answer 1

实现 OnBackStackChangedListener 并将此代码添加到您的 Fragment Activity。

@Override
public void onCreate(Bundle savedInstanceState) {
    //Listen for changes in the back stack
    getSupportFragmentManager().addOnBackStackChangedListener(this);
    //Handle when activity is recreated like on orientation Change
    shouldDisplayHomeUp();
}

@Override
public void onBackStackChanged() {
    shouldDisplayHomeUp();
}

public void shouldDisplayHomeUp(){
   //Enable Up button only  if there are entries in the back stack
   boolean canback = getSupportFragmentManager().getBackStackEntryCount()>0;
   getSupportActionBar().setDisplayHomeAsUpEnabled(canback);
}

@Override
public boolean onSupportNavigateUp() {
    //This method is called when the up button is pressed. Just the pop back stack.
    getSupportFragmentManager().popBackStack();
    return true;
}

如果您在 ActionBar 选项卡旁边寻找返回箭头。使用 Sherlock 可以做到。试试这个

https://stackoverflow.com/a/12703960/2365507