Question

我已经尝试了getActivity().findViewById()和getView()。这是我片段中的代码。它们都返回null ..

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.edit_viewer, container, false);

    Bundle bundle = getArguments();
    id = bundle.getLong("VIEWER_ID");

    DatabaseHelper dbHelper = new DatabaseHelper(getActivity());

    username = (EditText)getView().findViewById(R.id.username);
    password = (EditText)getView().findViewById(R.id.entry);
    hostUrl = (EditText)getView().findViewById(R.id.hostUrl);
    webApp = (EditText)getView().findViewById(R.id.webApp);
    modelId = (EditText)getView().findViewById(R.id.modelId);
    properties = (EditText)getView().findViewById(R.id.properties);

活动代码

public class EditViewerActivity extends ActionBarActivity {
    private Long id;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_edit_viewer);

        Intent intent = getIntent();
        Long id = intent.getLongExtra("VIEWER_ID", 0);

        ViewerEditFragment newFragment = new ViewerEditFragment();
        Bundle bundle = new Bundle();
        bundle.putLong("VIEWER_ID", id);
        newFragment.setArguments(bundle);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, newFragment)
                    .commit();
        }

    }

edit_viewer.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/edit_viewer"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">

    <TextView
        style="?android:attr/listSeparatorTextViewStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="sfn Credentials"/>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/username"
            android:paddingLeft="10dp" />
        <EditText
            android:id="@+id/username"
            android:hint="Admin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/password"
            android:paddingLeft="10dp" />
        <EditText
            android:id="@+id/entry"
            android:inputType="textPassword"
            android:hint="Password"
            android:minWidth="100dip"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>

    <TextView
        style="?android:attr/listSeparatorTextViewStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Host Settings"/>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/host_url"
            android:paddingLeft="10dp" />
        <EditText
            android:id="@+id/hostUrl"
            android:hint="http://www.mysfn.com"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/web_app"
            android:paddingLeft="10dp" />
        <EditText
            android:id="@+id/webApp"
            android:hint="sfn"
            android:minWidth="100dip"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/model_id"
            android:paddingLeft="10dp" />
        <EditText
            android:id="@+id/modelId"
            android:hint="aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/properties"
            android:paddingLeft="10dp" />
        <EditText
            android:id="@+id/properties"
            android:hint="dv=icon"
            android:minWidth="100dip"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>

    <Button android:id="@+id/close"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:text="Save" />
</LinearLayout>

Answer 1

更改此

 username = (EditText)getView().findViewById(R.id.username);

到

 username = (EditText)rootView.findViewById(R.id.username);

并为所有其他Views

执行相同的操作

Answer 2

getView返回您在onCreateView中夸大的视图，在onCreateView返回之前，该视图不可用。您应该使用膨胀的视图来检索您的组件或覆盖以onViewCreated为参数的View，并使用它来检索您的组件。 Here您可以找到onViewCreated的文档

在onCreateView（LayoutInflater，ViewGroup， Bundle）已经返回，但在恢复任何已保存的状态之前到了视野。这为子类提供了初始化自己的机会一旦他们知道他们的视图层次结构已经完全创建。

Answer 3

你应该这样打电话：

username = (EditText) rootView.findViewById(R.id.username);

Fragment中的findViewById返回Null

3 个答案: