创建自定义 LinearLayout 并用视图填充它
Create custom LinearLayout and fill it with Views
我在 main.xml 文件中有一个主 LinearLayout
,它在 Activity 中设置 (setContentView
) ].进入主要 LinearLayout
我想添加 1-X 自定义 LinearLayouts。所以我创建了一个 XML "template" detail_line.xml :
<?xml version="1.0" encoding="utf-8"?>
<com.test.layout.DetailLine
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingBottom="@dimen/button_bottom_padding">
<LinearLayout
android:id="@+id/purpleLine"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_weight="2"
android:orientation="horizontal">
<!-- programmatically add other views -->
</LinearLayout>
<!-- more "purpleLines" will be coming but for now it's not a point of interest -->
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingBottom="@dimen/detail_save_buttons"
android:paddingTop="@dimen/detail_save_buttons">
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/darker_gray" />
</LinearLayout>
</com.test.layout.DetailLine>
这是 Class:
public class DetailLine extends LinearLayout {
private Map<String, String> row;
private Context context;
public DetailLine(Context context) {
super(context);
this.context = context;
this._create();
}
public DetailLine(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
this._create();
}
public DetailLine(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
this.context = context;
this._create();
}
/**
* Inflates XML layout
*/
private void _create() {
this._purpleLine();
}
/**
* Creates purple line
*/
private void _purpleLine() {
LinearLayout purpleLine = (LinearLayout) this.findViewById(R.id.purpleLine);
purpleLine.removeAllViews(); // NullPointerException thrown here
// Add views...
}
}
NullPointerException
在使用自定义 LinearLayout 的子视图时抛出。看起来 XML 和 Class 之间没有任何联系。我尝试调用 LayoutInflater.from(this.context).inflate(R.layout.detail_line, null);
,但没有成功。我已经检查了教程 over here,但我并不聪明,而是对 <merge>
的东西感到困惑。
您正在 DetailLine
的构造函数中调用 _create()
,但它还没有子项。您需要改写 onFinishInflate()
,然后您可以访问其子项:
protected void onFinishInflate() {
LinearLayout purpleLine = (LinearLayout) this.findViewById(R.id.purpleLine);
purpleLine.removeAllViews();
...
}
我终于找到了正确答案。需要做的就是以不同的方式扩充 LinearLayout
文件并将自定义布局名称 (com.test.layout.DetailLine
) 更改回 LinearLayout
.
private void _create() {
inflate(this.context, R.layout.detail_line, this);
this._purpleLine();
}
致谢:http://trickyandroid.com/protip-inflating-layout-for-your-custom-view/
我在 main.xml 文件中有一个主 LinearLayout
,它在 Activity 中设置 (setContentView
) ].进入主要 LinearLayout
我想添加 1-X 自定义 LinearLayouts。所以我创建了一个 XML "template" detail_line.xml :
<?xml version="1.0" encoding="utf-8"?>
<com.test.layout.DetailLine
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingBottom="@dimen/button_bottom_padding">
<LinearLayout
android:id="@+id/purpleLine"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_weight="2"
android:orientation="horizontal">
<!-- programmatically add other views -->
</LinearLayout>
<!-- more "purpleLines" will be coming but for now it's not a point of interest -->
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingBottom="@dimen/detail_save_buttons"
android:paddingTop="@dimen/detail_save_buttons">
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/darker_gray" />
</LinearLayout>
</com.test.layout.DetailLine>
这是 Class:
public class DetailLine extends LinearLayout {
private Map<String, String> row;
private Context context;
public DetailLine(Context context) {
super(context);
this.context = context;
this._create();
}
public DetailLine(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
this._create();
}
public DetailLine(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
this.context = context;
this._create();
}
/**
* Inflates XML layout
*/
private void _create() {
this._purpleLine();
}
/**
* Creates purple line
*/
private void _purpleLine() {
LinearLayout purpleLine = (LinearLayout) this.findViewById(R.id.purpleLine);
purpleLine.removeAllViews(); // NullPointerException thrown here
// Add views...
}
}
NullPointerException
在使用自定义 LinearLayout 的子视图时抛出。看起来 XML 和 Class 之间没有任何联系。我尝试调用 LayoutInflater.from(this.context).inflate(R.layout.detail_line, null);
,但没有成功。我已经检查了教程 over here,但我并不聪明,而是对 <merge>
的东西感到困惑。
您正在 DetailLine
的构造函数中调用 _create()
,但它还没有子项。您需要改写 onFinishInflate()
,然后您可以访问其子项:
protected void onFinishInflate() {
LinearLayout purpleLine = (LinearLayout) this.findViewById(R.id.purpleLine);
purpleLine.removeAllViews();
...
}
我终于找到了正确答案。需要做的就是以不同的方式扩充 LinearLayout
文件并将自定义布局名称 (com.test.layout.DetailLine
) 更改回 LinearLayout
.
private void _create() {
inflate(this.context, R.layout.detail_line, this);
this._purpleLine();
}
致谢:http://trickyandroid.com/protip-inflating-layout-for-your-custom-view/