從功能訪問片段的活動與功能

Question

我想動態地改變一個文本片段textview裏面的活動，但我不斷得到'無法獲得根'的錯誤。我試圖在onCreateView和onActivityCreated內部實例化textview，但它不起作用。如何更改活動內的片段文本視圖中的文本？

片段的xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:orientation="vertical"> 
<TextView 
     android:id="@+id/textView" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_centerInParent="true" 
     android:text="Tab 1" 
     android:textAppearance="?android:attr/textAppearanceLarge"/> 
</RelativeLayout> 

片段編碼：

public class TabFragment1 extends Fragment { 
    private TextView tv; 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View view = inflater.inflate(R.layout.tab_fragment_1, container, false); 
     return view; 
    } 
    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 
     tv = (TextView) getView().findViewById(R.id.textView); 
    } 
    public void setText(String text){ 
     tv.setText(text); 
    } 

} 

主要的xml：

<RelativeLayout 
    android:id="@+id/main_layout" 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context=".MainActivity"> 

    <android.support.v7.widget.Toolbar 
     android:id="@+id/toolbar" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_alignParentTop="true" 
     android:background="?attr/colorPrimary" 
     android:elevation="6dp" 
     android:minHeight="?attr/actionBarSize" 
     android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" 
     app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/> 

    <android.support.design.widget.TabLayout 
     android:id="@+id/tab_layout" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_below="@+id/toolbar" 
     android:background="?attr/colorPrimary" 
     android:elevation="6dp" 
     android:minHeight="?attr/actionBarSize" 
     android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"/> 

    <android.support.v4.view.ViewPager 
     android:id="@+id/pager" 
     android:layout_width="match_parent" 
     android:layout_height="fill_parent" 
     android:layout_below="@id/tab_layout"/> 
</RelativeLayout> 

主代碼：

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 1")); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 2")); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 3")); 
     tabLayout.setTabGravity(TabLayout.GRAVITY_FILL); 

     final ViewPager viewPager = (ViewPager) findViewById(R.id.pager); 
     final PagerAdapter adapter = new PagerAdapter 
       (getSupportFragmentManager(), tabLayout.getTabCount()); 
     TabFragment1 t1 = new TabFragment1(); 
     TabFragment2 t2 = new TabFragment2(); 
     TabFragment3 t3 = new TabFragment3(); 
     adapter.newFrag(t1); 
     adapter.newFrag(t2); 
     adapter.newFrag(t3); 
     viewPager.setAdapter(adapter); 
     viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout)); 
     tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() { 
      @Override 
      public void onTabSelected(TabLayout.Tab tab) { 
       viewPager.setCurrentItem(tab.getPosition()); 
      } 

      @Override 
      public void onTabUnselected(TabLayout.Tab tab) { 

      } 

      @Override 
      public void onTabReselected(TabLayout.Tab tab) { 

      } 
     }); 
     t1.setText("HELLO WORLD"); 
    } 

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

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     int id = item.getItemId(); 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 
} 

PagerAdapter：

public class PagerAdapter extends FragmentStatePagerAdapter { 
    int mNumOfTabs; 
    List<Fragment> aFrag; 
    public PagerAdapter(FragmentManager fm, int NumOfTabs) { 
     super(fm); 
     this.mNumOfTabs = NumOfTabs; 
     aFrag = new ArrayList<Fragment>(); 
    } 
    public void newFrag(Fragment f){ 
     aFrag.add(f); 
    } 
    @Override 
    public Fragment getItem(int position) { 

     return aFrag.get(position); 
    } 

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

Answer 1

您嘗試設置上查看文本，但並沒有創造這個觀點，是不是創造了這個片段。如果您想從活動中設置文本，您可以將包轉換爲片段帶有該文本的參數，以及片段chceck包和設置文本。稍後如果你想改變這個片段中的文本，那麼你可以使用你的函數。

TabFragment1 t1 =TabFragment1.create("HELLO WORLD"); 

的你的基地代碼性交執行：

public class TabFragment1 extends Fragment { 
private TextView tv; 

public static TabFragment1 create(String text){ 
    Bundle b = new Bundle(); 
    b.putString("textdata",text); 
    TabFragment1 f = new TabFragment1(); 
    f.setArguments(b); 
    return f; 
} 
@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    View view = inflater.inflate(R.layout.tab_fragment_1, container, false); 
    tv = (TextView) view.findViewById(R.id.textView); 
    if(getArguments()!=null){ 
     tv.setText(getArguments().getString("textdata")); 
    } 

    return view; 
} 

    public void setText(String text){ 
    tv.setText(text); 
} 

} 

在你的活動採用靜態方法來創建這個片段

new Handler().postDelayed(new Runnable(){t1.setText("HELLO WORLD");},300);