Android开发高级组件--ExpandableListView(可伸展的列表组件)
1、在Android开发中，有时候希望对列表项可以分组管理并实现收缩功能，例如QQ在使用时，有“我的好友”、“家人”、“同学”等分组，单击其中一项会展开，再单击一次又缩回去。要实现这种功能，就得使用到我们今天的主角ExpandableListView组件了。
2、该组件层次结构关系如下：
java.lang.Object
android.view.View
android.view.ViewGroup
androidwidget.AdapterView<Textendsandroid.widget.Adapter>
android.widget.AbsListView
android.widget.ListView
android.widget.ExpandableListView
3、每一个可扩展项旁边都有一个提示符（箭头等）用来说明该列表项目前的状态，可以使用方法：setChildIndicator(Drawable)和setGroupIndicator(Drawable)（或相应的XML文件的属性）去设置这些提示符的样式。注意：在XML布局文件中，一般不对ExpandableListView的android:layout_height属性使用wrap_content，否则可能会报错。
与ListView一样ExpandableListView也需要一个适配器做桥梁来提供数据，ExpandableListView是一个垂直滚动显示两级列表项，它可以有两层，每层都能够独立的展开并显示其子项。BaseExpandableListAdapter是一个用在ExpandableListView组件的适配器。
4、创建布局文件
<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:textSize="24sp"
android:gravity="center"
android:text="花名册"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
<ExpandableListView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/list"
android:background="#abcdef"/>
</LinearLayout>
5、修改ExpandableActivity.java文件
packagexiao.fuyan.testapp;
importandroid.app.Activity;
importandroid.graphics.Color;
importandroid.os.Bundle;
importandroid.view.Gravity;
importandroid.view.View;
importandroid.view.ViewGroup;
importandroid.widget.AbsListView;
importandroid.widget.BaseExpandableListAdapter;
importandroid.widget.ExpandableListAdapter;
importandroid.widget.ExpandableListView;
importandroid.widget.ImageView;
importandroid.widget.LinearLayout;
importandroid.widget.TextView;
/**
*Createdbyxiaoon2017/1/6.
*/
publicclassExpandableActivityextendsActivity{
@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.expandable_xml);
//
ExpandableListAdapteradapter=newBaseExpandableListAdapter(){
int[]logos=newint[]{R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher};
privateString[]generalsTypes=newString[]{"1","2","3"};
privateString[][]generals=newString[][]{
{"a","b","c","d"},
{"e","f","g","h"},
{"i","j","k","l"}
};
privateint[][]generalsLogos=newint[][]{
{R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher},
{R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher},
{R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher}
};
TextViewgetTextView(){
AbsListView.LayoutParamslp=newAbsListView.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,64
);
TextViewtextView=newTextView(ExpandableActivity.this);
textView.setLayoutParams(lp);
textView.setGravity(Gravity.CENTER_VERTICAL);
textView.setPadding(36,0,0,0);
textView.setTextSize(16);
textView.setTextColor(Color.BLACK);
returntextView;
}
@Override
publicintgetGroupCount(){
returngeneralsTypes.length;
}
@Override
publicintgetChildrenCount(intgroupPosition){
returngenerals[groupPosition].length;
}
@Override
publicObjectgetGroup(intgroupPosition){
returngeneralsTypes[groupPosition];
}
@Override
publicObjectgetChild(intgroupPosition,intchildPosition){
returngenerals[groupPosition][childPosition];
}
@Override
publiclonggetGroupId(intgroupPosition){
returngroupPosition;
}
@Override
publiclonggetChildId(intgroupPosition,intchildPosition){
returnchildPosition;
}
@Override
publicbooleanhasStableIds(){
returntrue;
}
@Override
publicViewgetGroupView(intgroupPosition,booleanisExpanded,ViewconvertView,ViewGroupparent){
LinearLayoutll=newLinearLayout(ExpandableActivity.this);
ll.setOrientation(LinearLayout.HORIZONTAL);
ImageViewlogo=newImageView(ExpandableActivity.this);
logo.setImageResource(logos[groupPosition]);
logo.setPadding(20,0,0,0);
ll.addView(logo);
TextViewtextView=getTextView();
textView.setTextColor(Color.BLACK);
textView.setText(getGroup(groupPosition).toString());
ll.addView(textView);
returnll;
}
@Override
publicViewgetChildView(intgroupPosition,intchildPosition,booleanisLastChild,ViewconvertView,ViewGroupparent){
LinearLayoutll=newLinearLayout(ExpandableActivity.this);
ll.setOrientation(LinearLayout.HORIZONTAL);
ImageViewgeneralLogo=newImageView(ExpandableActivity.this);
generalLogo.setImageResource(generalsLogos[groupPosition][childPosition]);
ll.addView(generalLogo);
TextViewtextView=getTextView();
textView.setText(getChild(groupPosition,childPosition).toString());
ll.addView(textView);
returnll;
}
@Override
publicbooleanisChildSelectable(intgroupPosition,intchildPosition){
returntrue;
}
};
ExpandableListViewexpandableListView=(ExpandableListView)
findViewById(R.id.list);
expandableListView.setAdapter(adapter);
}
}