[英]Converting view with toolbar from Activity to Fragment
我有一個帶有工具欄,導航抽屜和內容自定義視圖的AppCompatActivity屏幕。 我想顯示一個配置。 我不會使用對話框,因為它會很大並且會打開對話框。 我的朋友建議我重寫代碼以包含兩個片段,並在它們之間切換。
當前代碼:
public class PuzzleActivity extends AppCompatActivity implements
NavigationView.OnNavigationItemSelectedListener
protected void onCreate(Bundle state) {
setContentView(R.layout.activity_puzzle);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.drawer_open, R.string.drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
activity_puzzle.xml(精簡版)
<android.support.v4.widget.DrawerLayout android:id="@+id/drawer_layout"
android:fitsSystemWindows="true" tools:openDrawer="start">
<include
layout="@layout/app_bar_puzzle"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:fitsSystemWindows="true"
app:menu="@menu/drawer_main" />
app_bar_puzzle.xml(精簡版)
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_puzzle" />
最后是content_puzzle.xml(再次減少,為簡單起見,自定義視圖已替換為textView)
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="Content"/>
最初,我創建了一個Fragment並將android.R.id.content替換為該片段:我最終得到了重疊的片段和原始視圖:
我有一個理論,這是由FragmentManager無法替換從XML定義的活動視圖或Activity視圖與片段之間不兼容引起的。 因此,我決定引入新的Fragment,並將所有UI移至該片段。
從支持庫派生的PuzzleFragment.java:
public class PuzzleFragment extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_puzzle, container, false);
Toolbar toolbar = (Toolbar) getActivity().findViewById(R.id.toolbar);
((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) getActivity().findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(getActivity(), drawer, toolbar, R.string.drawer_open, R.string.drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
return view;
}
但這在工具欄初始化上失敗:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.support.v7.widget.Toolbar.getTitle()' on a null object reference
at android.support.v7.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:98)
at android.support.v7.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:91)
at android.support.v7.app.ToolbarActionBar.<init>(ToolbarActionBar.java:73)
at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:205)
at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:99)
at PuzzleFragment.onCreateView(PuzzleFragment.java:30)
工具欄為null,在Fragment / inflater.inflate(R.layout.activity_puzzle, container, false
)/中找不到findViewById
。 但是如果在Activity / setContentView(R.layout.activity_puzzle)
/中,則可以。
我該如何運作?
訣竅是將初始化過程移至后續階段,如源代碼所示:
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Log.d(logTag, "onCreateView()");
return inflater.inflate(R.layout.activity_puzzle, container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
Log.d(logTag, "onActivityCreated()");
super.onActivityCreated(savedInstanceState);
Toolbar toolbar = (Toolbar) getActivity().findViewById(R.id.toolbar);
((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) getActivity().findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(getActivity(), drawer, toolbar, R.string.drawer_open, R.string.drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) getActivity().findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}
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