ExpandableListView怎樣實現(xiàn)

ExpandableListView是Android中的一種列表視圖，它允許用戶展開和折疊每個列表項以顯示子項。要實現(xiàn)ExpandableListView，你需要遵循以下步驟：

1. 創(chuàng)建布局文件： 在你的項目的res/layout目錄下，創(chuàng)建一個新的XML布局文件，例如expandable_list_item.xml，用于定義每個列表項的外觀。這個布局文件可以包含一個圖標(biāo)、一個標(biāo)題和一個可選的子項列表。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <ImageView
        android:id="@+id/icon"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:src="@drawable/ic_launcher_background" />

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="64dp"
        android:text="Group Item"
        android:textAppearance="?android:attr/textAppearanceListItemSmall" />
</LinearLayout>

對于子項，你可以創(chuàng)建另一個布局文件，例如list_item.xml。 2. 創(chuàng)建數(shù)據(jù)模型： 創(chuàng)建一個Java類來表示你的數(shù)據(jù)模型。這個類應(yīng)該包含父項和子項的數(shù)據(jù)。

public class ExpandableListGroup {
    private String title;
    private List<String> items;

    public ExpandableListGroup(String title, List<String> items) {
        this.title = title;
        this.items = items;
    }

    // Getters and setters
}

3. 創(chuàng)建適配器： 為了填充ExpandableListView，你需要創(chuàng)建一個自定義的適配器。這個適配器應(yīng)該繼承自BaseExpandableListAdapter。

public class MyExpandableListAdapter extends BaseExpandableListAdapter {
    private Context context;
    private List<ExpandableListGroup> groups;

    public MyExpandableListAdapter(Context context, List<ExpandableListGroup> groups) {
        this.context = context;
        this.groups = groups;
    }

    @Override
    public int getGroupCount() {
        return groups.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return groups.get(groupPosition).getItems().size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        return groups.get(groupPosition);
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return groups.get(groupPosition).getItems().get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        // Inflate the layout for the group item
        // Set the title and other attributes
        // Return the view
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        // Inflate the layout for the child item
        // Set the text or other attributes
        // Return the view
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
}

4. 在Activity中設(shè)置適配器： 在你的Activity中，初始化ExpandableListView并設(shè)置你的自定義適配器。

public class MainActivity extends AppCompatActivity {
    private ExpandableListView expandableListView;
    private MyExpandableListAdapter adapter;
    private List<ExpandableListGroup> groups;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        expandableListView = findViewById(R.id.expandableListView);

        // Initialize your data model
        groups = new ArrayList<>();
        // Add groups and children to the list

        // Initialize the adapter and set it to the ExpandableListView
        adapter = new MyExpandableListAdapter(this, groups);
        expandableListView.setAdapter(adapter);
    }
}

5. 處理點擊事件： 為了允許用戶展開和折疊列表項，你需要為ExpandableListView設(shè)置一個點擊監(jiān)聽器。

expandableListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
    @Override
    public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
        // Handle group click event
        return true; // Return true to allow the group to be expanded
    }
});

對于子項，你可以使用setOnChildClickListener來處理點擊事件。

以上是實現(xiàn)ExpandableListView的基本步驟。你可以根據(jù)需要自定義布局、數(shù)據(jù)模型和適配器以適應(yīng)你的具體需求。