Question

我的活动fragment1和fragment2中有两个片段，我想当用户点击fragment2的后退按钮时，它应该将用户导航到fragement1

我的活动xml代码是：我在xml中设置片段

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout     
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Routeplan" >       
    <FrameLayout 
        android:id="@+id/content_frame_polymer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >               


          <viewpager.helper.JazzyViewPager 
                    xmlns:android="http://schemas.android.com/apk/res/android"
                    android:id="@+id/pager"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"         
                />      

    </FrameLayout>   
</android.support.v4.widget.DrawerLayout>

我的活动代码：

public class MainActivity extends FragmentActivity  {

    @Override
    protected void onCreate(Bundle arg0) {

        super.onCreate(arg0);
        setContentView(R.layout.packing_activity);
        mPager = (JazzyViewPager)findViewById(R.id.pager);      
        PagerAdapter padapter = new PagerAdapter(getSupportFragmentManager(),NUM_PAGES,mPager);     
        mPager.setAdapter(padapter);        
        mPager.setPageMargin(30);       

    } 

}

PagerAdapter代码：

public class PagerAdapter extends FragmentPagerAdapter {
    int NUM_PAGES;
    JazzyViewPager mPager;
    public PagerAdapter(FragmentManager fm, int numPages, JazzyViewPager mPager) {
        super(fm);  
        this.NUM_PAGES=numPages;
        this.mPager=mPager;

        // TODO Auto-generated constructor stub
    }

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

        Object obj = super.instantiateItem(container, position);
        mPager.setObjectForPosition(obj, position);
        return obj;

    }

    @Override
    public Fragment getItem(int arg0) {
        // TODO Auto-generated method stub
        switch (arg0) {
        case 0:                 
            return new Fragmentone();         

        case 1:                 
            return new Fragmenttwo();           

        default:
            break;
        }
        return null;
    }

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

}

Fragmentone代码：

public class FragmentOne extends Fragment { 

    private ViewGroup rootView1;
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {                

         return rootView1 = (ViewGroup) inflater
                .inflate(R.layout.about_rohtak, container, false);

    }
}

Fragmenttwo代码：

public class FragmentTwo extends Fragment { 

    private ViewGroup rootView1;
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {                

         return rootView1 = (ViewGroup) inflater
                .inflate(R.layout.about_rohtak, container, false);

    }
}

Answer 1

基本上，您必须在Activity上覆盖onBackPressed方法并将处理逻辑传递给Fragment。在Fragment中，您需要监听Activity中发生的事件。有一些选项如何实现这些东西，但我更愿意通过接口进行通信，如果可能的话。这可以具体实施：

public MyActivity extends AppCompatActivity {

    private BackButtonListener backButtonListener;

    public interface BackButtonListener {
        void onBackButtonClicked();
    }

    public void setBackButtonListener(BackButtonListener backButtonListener) {
        this.backButtonListener = backButtonListener;           
    }

    public void onBackPressed() {
        if (null != backButtonListener) {
            backButtonListener.onBackButtonClicked();
        } else {
            super.onBackPressed();      
        }
    }
}

public MyFragment extends Fragment implements BackButtonListener {

    private ViewPager viewPager;

    public void onAttach(Activity activity) {
        super.onAttach(activity);

        if (activity instanceof MyActivity) {
            ((MyActivity) activity).setBackButtonListener(this);
        }
    }

    public void onBackButtonClicked() {
        if (0 != viewPager.getCurrentItem()) {
            viewPager.setCurrentItem(viewPager.getCurrentItem() - 1);
        }
    }
}

已修改：请谨慎实施此操作，因为您更改了自然导航顺序。想想你如何处理后退按钮然后当前viewpager项是第一个元素（位置0）。您应该知道如何判断片段对象（BackButtonListener）是否能够处理它并将处理逻辑传递回调用者或执行其他操作。这取决于情况。不久，总是对按下后退按钮的应用导航做一些有意义的事情。

单击后退按钮导航到上一个片段：

1 个答案: