2012年9月23日 星期日

Android程式設計 - 使用ExpandableList


ExpandableListView提供分組的項目清單介面,使用者可將每一組的清單內容展開或是折疊起來。
1.      首先要建立ExpandableListView所使用的版面,包括群組版面及群組的子版面。
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="wrap_content" >
  <TextView
     android:id="@+id/text_college"
     ... />
</RelativeLayout>
child.xml
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="wrap_content" >
  <ImageView
     android:id="@+id/image_go"
     ... />
  <TextView
     android:id="@+id/text_department"
     ... />
</RelativeLayout>



2.      建立ExpandableListView之資料轉接器
public class CollegeListAdapter extends BaseExpandableListAdapter {
  private Context context;     
  private ArrayList groups;
  private ArrayList> childs;
  public CollegeListAdapter(Context context, ArrayList groups, ArrayList> childs) {
     this.context = context;
     this.groups = groups;
     this.childs = childs;
  }
  public Object getChild(int groupPosition, int childPosition) {
     return childs.get(groupPosition).get(childPosition);
  }
  public long getChildId(int groupPosition, int childPosition) {
     return childPosition;
  }
  public View getChildView(int groupPosition, int childPosition,
       boolean isLastChild, View convertView, ViewGroup parent) {
     View childView;   
     @SuppressWarnings("unchecked")
     String department = childs.get(groupPosition).get(childPosition);
           LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
     //建立子清單元件, 並設置元件對應的內容
     childView = layoutInflater.inflate(R.layout.child, null);
           TextView dept_name = (TextView) childView.findViewById(R.id.text_department);
     dept_name.setText(department);
           ImageView imageView = (ImageView)childView.findViewById(R.id.image_go);
     imageView.setImageResource(R.drawable.ic_go);
     return childView; 
  }
  public int getChildrenCount(int groupPosition) {
     return childs.get(groupPosition).size();
  }
  public Object getGroup(int groupPosition) {
     return groups.get(groupPosition);
  }
  public int getGroupCount() {
     return groups.size();
  }
  public long getGroupId(int groupPosition) {
     return groupPosition;
  }
  public View getGroupView(int groupPosition, boolean isExpanded,
       View convertView, ViewGroup parent) {
     View groupView;   
     String college = groups.get(groupPosition);
           LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
     //建立群組元件,並設置元件對應的內容
     groupView = layoutInflater.inflate(R.layout.group, null);
           TextView college_name = (TextView)groupView.findViewById(R.id.text_college);
     college_name.setText(college);
     return groupView;
  }
  public boolean hasStableIds() {
     return false;
  }
  public boolean isChildSelectable(int groupPos, int childPos) {
     return false;      //如果想要子列表可被點選,要改為回傳true
  }
}

3. 建立ExpandableListView所要顯示資料串列。
  ArrayList group;                    //群組列表 
  ArrayList> child;        //子列表 
     ...
  private void initializeData(){ 
     group = new ArrayList(); 
     child = new ArrayList>();    
     addInfo("電資學院",
new String[]{"電子系","電機系","資訊系","電腦通訊系"}); 
     addInfo("工程學院",
new String[]{"機械系","自動化系","工管系"});
  } 
  private void addInfo(String g,String[] c){
     group.add(g); 
     ArrayList childitem = new ArrayList(); 
     for(int i=0;ilength;i++){ 
       childitem.add(c[i]); 
     } 
     child.add(childitem); 
  }   

4. 設定ExpandableListView資料轉接器
     expandablelist = (ExpandableListView) findViewById(R.id.expandableListView1);
     expandablelist.setAdapter(
new CollegeListAdapter(MainActivity.this, group, child));   






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