如何膨胀片段内的视图

如果我尝试膨胀一个片段内的视图,我得到NULL ..例如:

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Here I will inflate my view using the layout ID & return. return view; } 

每当一个button被点击,我需要创build一个dynamic视图,例如:button和添加到LinearLayout。 我想要像这样在我的片段类中执行此操作:

 public void addPlaces() { Button button = new Button(null); button.setText("button name"); // eg like adding button to enter code here linear layout linearLayout.addView(button); } 

所以,如果我在onCreateView里面使用LinearLayout,并且在add类中使用它,我会得到NULL。 如何实现?

Solutions Collecting From Web of "如何膨胀片段内的视图"

将variables声明为实例variables,然后初始化线性布局

 LinearLayout linearLayout; public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment1, container, false); linearLayout = (LinearLayout) rootView.findViewById(R.id.linearlayout); return rootView; } 

然后

 public void addPlaces() { Button button = new Button(getActivity()); // needs activity context // fragment hosted by a activity. use getActivity() to get the context of the hosting activity. button.setText("button name"); linearlayout.addView(button); } 

示例:根据您的要求修改以下内容。

fragment1.xml

 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:text="Button" /> <LinearLayout android:layout_width="fill_parent" android:id="@+id/linearlayout" android:layout_height="fill_parent" android:layout_above="@+id/button1" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:orientation="vertical" > </LinearLayout> </RelativeLayout> 

Myfragment.java

 public class Myfragment extends Fragment { LinearLayout linearLayout; View rootView; @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); Button b = (Button) rootView.findViewById(R.id.button1); b.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub addPlaces(); } }); linearLayout = (LinearLayout) rootView.findViewById(R.id.linearlayout); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { rootView = inflater.inflate(R.layout.fragment1, container, false); return rootView; } public void addPlaces() { Button button = new Button(getActivity()); // needs activity context button.setText("button name"); linearLayout.addView(button); } } 

我的模拟器的快照

在这里输入图像说明

编辑:

活动的main.xml中

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity" > <fragment android:name="com.example.fragments.Myfragment" android:id="@+id/frag" android:layout_above="@+id/button1" android:layout_width="fill_parent" android:layout_height="fill_parent" /> <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:text="Button" /> </RelativeLayout> 

MainActivity.java

 public class MainActivity extends FragmentActivity { Button b; Myfragment fragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); FragmentManager fragmentManager = getSupportFragmentManager(); FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); fragment = new Myfragment(); fragmentTransaction.add(R.id.frag, fragment); fragmentTransaction.commit(); b = (Button) findViewById(R.id.button1); b.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub fragment.addPlaces(); } }); } } 

Myfragment.java

 public class Myfragment extends Fragment { LinearLayout linearLayout; View rootView; @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); linearLayout = (LinearLayout) rootView.findViewById(R.id.linearlayout); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { rootView = inflater.inflate(R.layout.fragment1, container, false); return rootView; } public void addPlaces() { Button button = new Button(getActivity()); // needs activity context button.setText("button name"); linearLayout.addView(button); } }