如何动态地向数组中添加数据

Question

我的 ExpendableListView 适配器 class 中有 2 个数组，它们为我的组和 child headers 提供虚拟数据。第一个数组是常规数组，第二个数组是二维数组。

public class ExpandableListViewAdapter extends BaseExpandableListAdapter {

String[] groupNames = {
        "Fall 2016", "Winter 2017",
        "Fall 2017", "Winter 2018",
        "Fall 2018", "Winter 2019",
        "Fall 2019", "Winter 2020"
};

String[][] childNames = {
        {"JAVA101", "MATH101", "CHEM101"},{"JAVA201", "MATH201", "CHEM201"},
        {"JAVA301", "MATH301", "CHEM301"},{"JAVA401", "MATH401", "CHEM401"},
        {"JAVA501", "MATH501", "CHEM501"},{"JAVA601", "MATH601", "CHEM601"},
        {"JAVA701", "MATH701", "CHEM701"},{"JAVA801", "MATH801", "CHEM801"}
};

并且根据需要，我已经实现了所有必要的方法并将它们附加到我的数组中。

Context context;

    public ExpandableListViewAdapter(Context context){
        this.context = context;
    }

    @Override
    public int getGroupCount() {
        return groupNames.length;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return childNames[groupPosition].length;
    }

    @Override
    public Object getGroup(int groupPosition) {
        return groupNames[groupPosition];
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return childNames[groupPosition][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 view, ViewGroup parent) {
        TextView textView = new TextView(context);
        textView.setText(groupNames[groupPosition]);
        textView.setPadding(100,0,0,0);
        textView.setTextColor(Color.BLACK);
        textView.setTextSize(20);

        return textView;
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View view, ViewGroup parent) {
        final TextView textView = new TextView(context);
        textView.setText("Java" + groupNames[childPosition] + "01");
        textView.setPadding(100,0,0,0);
        textView.setTextColor(Color.BLACK);
        textView.setTextSize(10);

        textView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(context, textView.getText().toString(), Toast.LENGTH_SHORT).show();
            }
        });

        return textView;
    }

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

一切正常。我想要做的是通过 FAB 点击将数据动态添加到我的 ExpandableListView 中。我主要想知道是否需要在我的适配器中实现我的 FAB 按钮的 onClick() 功能。

Answer 1

first of all to add data dynamically use ArrayList

无需实现onclick()；在适配器中添加来自 activity onclick
然后使用notifyDatasetchanged();在适配器上，这将起到作用

Answer 2

数组的大小无法修改。如果你想要一个更大的数组，你必须实例化一个新的。更好的解决方案是使用可以根据需要增长的 ArrayList。

因此，在您的适配器中创建一个方法来将新项目添加到您现有的列表中。在方法中将新项目添加到 ArrayList 并调用 .notifyDataSetChanged().

将groupNames替换为

List<String> places = Arrays.asList("Fall 2016", "Winter 2017", "Fall 2017", "Winter 2018", "Fall 2018", "Winter 2019", "Fall 2019", "Winter 2020");

对于childNames你必须这样做

List<String[]> childNames = Arrays.asList(new String[]{"JAVA101", "MATH101", "CHEM101"}, new String[]{ "JAVA201", "MATH201", "CHEM201" } etc...);

或

List<String[]> childNames = new ArrayList<String[]>();
childNames.add(new String[]{"JAVA101", "MATH101", "CHEM101"});
//etc...

您还必须更改您的适配器以使用 ArrayLists 而不是 Arrays，我希望您明白了

如何动态地向数组中添加数据

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