如何膨胀片段内的视图 [英] How to inflate view inside fragment
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问题描述
如果我试图在片段中膨胀视图，我会得到NULL ..例如：
public View onCreateView LayoutInflater inflater，ViewGroup容器，
Bundled savedInstanceState）{
//这里我将使用布局ID&返回。
返回视图;
}
每当点击一个按钮时，我需要创建一个动态视图，例如：button& amp ;添加到LinearLayout。我想在我的片段类中执行此操作，如下所示：
public void addPlaces（）{
Button按钮= new Button（null）;
button.setText（button name）;
//例如像添加按钮在这里输入代码线性布局
linearLayout.addView（button）;
$ b因此，如果我在onCreateView中使用LinearLayout并在add类中使用它，我得到NULL。如何实现？解决方案将变量声明为实例变量，然后初始化线性布局
LinearLayout linearLayout;
$ b $ public查看onCreateView（LayoutInflater inflater，ViewGroup容器，
Bundle savedInstanceState）{
查看rootView = inflater.inflate（R.layout.fragment1，container，false）;
linearLayout =（LinearLayout）rootView.findViewById（R.id.linearlayout）;
返回rootView;
然后
public void addPlaces（）{
Button button = new Button（getActivity（））;
//需要活动上下文
//活动托管的片段。使用getActivity（）来获取托管活动的上下文。
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 = 1.0encoding =utf-8？>
< RelativeLayout xmlns：android =http://schemas.android.com/apk/res/android
android：layout_width =match_parent
android：layout_height =match_parent >
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;
查看rootView;
@Override
public void onActivityCreated（Bundle savedInstanceState）{
super.onActivityCreated（savedInstanceState）;
Button b =（Button）rootView.findViewById（R.id.button1）;
b.setOnClickListener（new OnClickListener（）{
$ b $ @Override
public void onClick（View v）{
// TODO自动生成的方法存根
addPlaces（）;
}
}）;
linearLayout =（LinearLayout）rootView.findViewById（R.id.linearlayout）;
$ b @Override
public View onCreateView（LayoutInflater inflater，ViewGroup container，
Bundled savedInstanceState）{
rootView = inflater.inflate（R.layout .fragment1，container，false）;
返回rootView;
}
public void addPlaces（）{
Button button = new Button（getActivity（））; //需要活动上下文
button.setText（button name）;
linearLayout.addView（button）;
我的模拟器快照
编辑：
activity-main.xml
< RelativeLayout xmlns：android =http://schemas.android.com/apk/res/android
xmlns：tools =http://schemas.android.com/工具
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/>
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片段;
@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（）{
$ b $ @Override
public void onClick（View v）{
// TODO自动生成的方法存根
fragment.addPlaces（）;
}
}）;
}
}
Myfragment.java
public class Myfragment extends Fragment {
LinearLayout linearLayout;
查看rootView;
@Override
public void onActivityCreated（Bundle savedInstanceState）{
super.onActivityCreated（savedInstanceState）;
linearLayout =（LinearLayout）rootView.findViewById（R.id.linearlayout）;
$ b @Override
public View onCreateView（LayoutInflater inflater，ViewGroup container，
Bundled savedInstanceState）{
rootView = inflater.inflate（R.layout .fragment1，container，false）;
返回rootView;
}
public void addPlaces（）{
Button button = new Button（getActivity（））; //需要活动上下文
button.setText（button name）;
linearLayout.addView（button）;
}
}
If I try to inflate a view within a fragment I am getting NULL.. For example:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Here I will inflate my view using the layout ID & return.
return view;
}
Whenever a button is clicked I need to create a dynamic view e.g.: button & add to the LinearLayout. I would like to perform this operation inside my fragment class like this:
public void addPlaces() {
Button button = new Button(null);
button.setText("button name");
// e.g. like adding button to enter code here linear layout
linearLayout.addView(button);
}
So, if I get inflate LinearLayout inside onCreateView and use it in add class, I'm getting NULL. How to achieve?
解决方案 Declare the variable as a instance variable and then initialize Linear Layout
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;
}
Then
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);
}
Example: Modify the below according to your requirement.
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);
}
}
Snap shot of my emulator
Edit :
activity-main.xml
<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);
}
}
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