android 列表视图如何实现多选 - 问答

在Android中，要实现ListView的多选功能，你可以使用ListView.MultiChoiceMode。以下是实现多选功能的步骤：

在布局文件中创建一个ListView，并设置其choiceMode属性为MultiChoiceMode.MULTIPLE或MultiChoiceMode.SINGLE。例如：

<ListView
    android:id="@+id/listView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:choiceMode="multiple" />

创建一个自定义的ArrayAdapter，以便在列表项上显示复选框。例如：

public class MultiChoiceArrayAdapter extends ArrayAdapter<String> {
    private final Context context;
    private final List<String> items;
    private final int resource;

    public MultiChoiceArrayAdapter(Context context, int resource, List<String> items) {
        super(context, resource, items);
        this.context = context;
        this.items = items;
        this.resource = resource;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;

        if (convertView == null) {
            LayoutInflater inflater = LayoutInflater.from(context);
            convertView = inflater.inflate(resource, parent, false);

            viewHolder = new ViewHolder();
            viewHolder.textView = convertView.findViewById(android.R.id.text1);
            viewHolder.checkbox = convertView.findViewById(android.R.id.checkbox);

            viewHolder.checkbox.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    boolean isChecked = ((CheckBox) v).isChecked();
                    if (isChecked) {
                        getSelection().add(getItem(position));
                    } else {
                        getSelection().remove(getItem(position));
                    }
                }
            });

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        viewHolder.textView.setText(getItem(position));

        return convertView;
    }

    static class ViewHolder {
        TextView textView;
        CheckBox checkbox;
    }
}

在Activity中，初始化ListView和自定义的ArrayAdapter，并将它们设置给ListView。例如：

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private MultiChoiceArrayAdapter adapter;
    private List<String> items;

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

        listView = findViewById(R.id.listView);

        items = new ArrayList<>();
        items.add("Item 1");
        items.add("Item 2");
        items.add("Item 3");
        items.add("Item 4");

        adapter = new MultiChoiceArrayAdapter(this, android.R.layout.simple_list_item_multiple_choice, items);
        listView.setAdapter(adapter);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                CheckBox checkBox = (CheckBox) view.findViewById(android.R.id.checkbox);
                if (checkBox.isChecked()) {
                    // 如果复选框已选中，将其添加到已选择项目的列表中
                    getSelection().add(items.get(position));
                } else {
                    // 如果复选框未选中，将其从已选择项目的列表中移除
                    getSelection().remove(items.get(position));
                }
            }
        });
    }
}

现在，你已经成功实现了ListView的多选功能。用户可以按住Shift键或Ctrl键（或Cmd键，适用于Mac）并单击其他列表项以选择多个项目。

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