图中有三个item = = 三个点也算一个。不管怎么弄我都没法把那仨点居中....
我用的 new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
分割线:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/divider"
android:layout_gravity="center_horizontal">
<TextView
android:width="7dp"
android:height="7dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="center_horizontal"
android:background="@drawable/round"
android:layout_marginBottom="3dp"/>
<TextView
android:layout_marginBottom="3dp"
android:width="7dp"
android:height="7dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="center_horizontal"
android:background="@drawable/round" />
<TextView
android:width="7dp"
android:height="7dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="center_horizontal"
android:background="@drawable/round" />
</LinearLayout>
RecyclerView:
<LinearLayout
android:orientation="vertical"
android:layout_below="@+id/type"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/result_container"
android:layout_above="@+id/actions">
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/scan_result"
/>
</LinearLayout>
没仔细看代码,直接丢到AS里,文字是可以居中的。。。
Ps. 为什么不用RelativeLayout
,多好控制。。。
result = new DividerHolder(mInflater.inflate(R.layout.divider, null));
把parent传进去,如:
result = new DividerHolder(mInflater.inflate(R.layout.divider, parent, false));
inflater在inflate一个xml时,需要知道parent的类型,才能生成对应的LayoutParams,才可以把xml根节点的attrs(如layout_width)读进去,代码如下:
// android.view.LayoutInflater
public View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {
synchronized (mConstructorArgs) {
...
// Temp is the root view that was found in the xml
final View temp = createViewFromTag(root, name, inflaterContext, attrs);
ViewGroup.LayoutParams params = null;
if (root != null) {
if (DEBUG) {
System.out.println("Creating params from root: " +
root);
}
// Create layout params that match root, if supplied
params = root.generateLayoutParams(attrs);
if (!attachToRoot) {
// Set the layout params for temp if we are not
// attaching. (If we are, we use addView, below)
temp.setLayoutParams(params);
}
}
...
}
如果parent传进去为null,生成的View的LayoutParams为null,在RecyclerView.addView时,发现LayoutParams为null,则生成默认的LayoutParams,
// android.view.ViewGroup
protected LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}
所以无论无论你怎么写,最外层的LinearLayout宽度为WRAP_CONTENT,如果那三个点的宽度为6dp,那么整个View的宽度也为6dp,所以无法居中。
衍生1,为何ListView加进去就是MATCH_PARENT的?
因为AbsListView重写的generateDefaultLayoutParams方法为
// android.widget.AbsListView
@Override
protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
return new AbsListView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT, 0);
}
衍生2,为何高度只能用minHeight控制?
同理,layout.xml根节点的attrs属性没被写到LayoutParams中!所以使用minHeight来控制高度的做法是可笑的!你所要做的是在inflate时把parent传进去!
把LinearLayout
的android:layout_gravity="center_horizontal"
改为android:gravity="center_horizontal"
。另外,三个TextView
的android:layout_gravity="center_horizontal"
可以去掉,对于LinearLayout
的子布局,这个属性无效