android - 无法解决java.lang.IndexOutOfBoundsException : Invalid index 1, size is 0

Question

在 Edit_WorkDetails 中，它有一个 listView 用于填充从 SQLite 检索的数据。

     ListView listViewUpdate;
     CustomBaseAdapter obj;
     private SimpleCursorAdapter dataAdapter;
     Long ID, iD;
     ArrayList<DetailsBean> results = new ArrayList<DetailsBean>();

     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View edit_details = inflater.inflate(R.layout.edit_work_details, container, false);
            dbHelper = new MyDatabaseHelper(getActivity());
            sqlcon = new WorkDetailsAPI(getContext());
            listViewUpdate = (ListView) edit_details.findViewById(R.id.listViewEdit);
            obj = new CustomBaseAdapter(getActivity(), results, listViewUpdate);
            listViewUpdate.setAdapter(obj);
            Bundle bundle = this.getArguments();
            if (getArguments() != null) {
                ID = bundle.getLong("ID"); // receive ID from other activity, Assume is ID=1
                BuildEditDetails(ID);
            }

     public void BuildEditDetails(long ID) {
            final long id = ID;
            Toast.makeText(getActivity(), id + "", Toast.LENGTH_LONG).show();
            sqlcon.open();
            Cursor cursor = sqlcon.readData(id);

            String[] columns = new String[]{MyDatabaseHelper.Project, MyDatabaseHelper.WorkDescription};

            int[] to = new int[]
                    {
                         R.id.Project, R.id.Description     };
            dataAdapter = new SimpleCursorAdapter(getActivity(), R.layout.retrieve_details, cursor, columns, to, 0);

            listViewUpdate.setAdapter(dataAdapter);

        }

点击列表后，会进入Edit_Details进行编辑。

  listViewUpdate.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> listView, View view,
                                    int position, long id) {
                mClickedPosition = position;
                Cursor cursor = (Cursor) listView.getItemAtPosition(position);
                iD = cursor.getLong(cursor.getColumnIndexOrThrow("_id"));
                Toast.makeText(getActivity(), iD + "", Toast.LENGTH_LONG).show();
                Intent intent = new Intent(getActivity(), Edit_Details.class);
                intent.putExtra("ID", iD);
                startActivityForResult(intent, PROJECT_REQUEST_CODE);

            }
        });

iD表示listView中的id，显示值2。

Edit_Details

所有属于 iD (2) 的数据将显示在 Edit_Details 中。单击保存 按钮 时，更新的值将保存到 SQLite 并返回到 Edit_WorkDetails listView。

save.setOnClickListener(new View.OnClickListener() {     // if save button clicked
            @Override
            public void onClick(View v) {
                Intent returnIntent = new Intent();
                project1=Project2.getSelectedItem().toString();
                description=Description.getText().toString();
                sqlcon.open();
                sqlcon.Update(ID, project1, description);  // update the latest value in SQLite
                returnIntent.putExtra("project1", project1);
                returnIntent.putExtra("description", description);
                setResult(Activity.RESULT_OK, returnIntent);
                finish();

            }
        });

这是 Edit_WorkDetails 的 OnActivityResult

 @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) { // receive from Activity B and populate ListView A
        if (resultCode == Activity.RESULT_OK) {
            if (requestCode == PROJECT_REQUEST_CODE) {
                ReceiveProject = data.getStringExtra("Project");
                ReceiveDescription = data.getStringExtra("Description");

                if (mClickedPosition == -1) {  // if icon clicked
                    if (obj != null) {
                        Toast.makeText(getActivity(), "S", Toast.LENGTH_LONG).show();
                    }

                } else {
                    if (obj != null)  // obj is CustomBaseAdapter object
                        obj.changeItem(mClickedPosition, ReceiveProject, ReceiveDescription);

                }
            }
        }
    }

自定义基础适配器

public class CustomBaseAdapter extends BaseAdapter{   // for ListView


    private static ArrayList<DetailsBean> searchArrayList;
    private LayoutInflater mInflater;
    ListView listview;


    public CustomBaseAdapter(Context context, ArrayList<DetailsBean> results,ListView listview) {
        searchArrayList = results;
        this.listview=listview;
         mInflater = LayoutInflater.from(context);

    }

    public void changeItem(int m,String P,String D)
    {
       DetailsBean obj = new DetailsBean();
        obj.setProject("   "+P);
        obj.setDescription("  "+" Work Description : " + " "+D);
        searchArrayList.set(m,obj);
        this. notifyDataSetChanged();
    }


    public int getCount() {
        return searchArrayList.size();
    }


    public Object getItem(int position) {
        return searchArrayList.get(position);
    }

    public long getItemId(int position) {
        return position;
    }

细节 bean

private String project="";
 private String description="";

public class DetailsBean {

  public void setProject(String project){
            this.project=project;
        }

        public String getProject()
        {
            return project;
        }


public void setDescription(String description){
            this.description=description;
        }

        public String getDescription()
        {
            return description;
        }

    }

单击 Edit_Details 中的保存按钮时，应用程序崩溃。

LogCat 错误

  Caused by: java.lang.IndexOutOfBoundsException: Invalid index 1, size is 0
            at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
            at java.util.ArrayList.set(ArrayList.java:481)
            at com.example.project.myapplication.Adapter.CustomBaseAdapter.changeItem(CustomBaseAdapter.java:47)
            at com.example.project.myapplication.GUI.Edit_WorkDetails.onActivityResult(Edit_WorkDetails.java:125)
            at android.support.v4.app.FragmentActivity.onActivityResult(FragmentActivity.java:156)

有人可以帮助我吗？

这两个代码有错误

 obj.changeItem(mClickedPosition, ReceiveProject, ReceiveDescription);

和

searchArrayList.set(m,obj);

Answer 1

我认为您的自定义适配器中的这个成员类不应该是静态的:

static ArrayList<DetailsBean> searchArrayList;

“静态”意味着它与类关联，而不是实例。当您在构造函数中设置它时，每个实例都是如此。

这也是个坏主意:

searchArrayList = results;

您应该复制一份以使引用保持私密:

this.searchArrayList = new ArrayList<DetailsBean>(results);

这是有问题的行:

searchArrayList.set(m,obj);

您传入 m=1，但 List 已被初始化，因此它是空的。

ArrayList<DetailsBean> results = new ArrayList<DetailsBean>();

这是您在创建 CustomBaseAdapter 时传递给构造函数的列表。我看不出你在哪里改变它。这些结果来自 SQL 数据库吗？也许您的查询没有返回任何结果，但您认为它返回了结果。

什么是 DetailsBean？这是两个通用名称的组合，无法提供有关此对象是什么的任何见解。我会重新考虑的。看起来您想要在该对象中包含项目名称和描述。为什么不称它为 Project？就是这样。

那些私有(private)变量是否应该在您的 DetailsBean 中？如果没有，谁拥有它们？这看起来也不对。这甚至可以编译吗？

您的代码不遵循 Java 编码标准。您的命名不一致且令人困惑。变量名应以小写字母开头；类以大写字母开头。