Question

我有电话本应用程序，它在sqlite表中存储新的联系人。我有活动要添加和（列表）查看联系人，他们工作得很好现在，我需要一个Details活动，它将显示listView中cliked的联系人详细信息。我知道我应该使用onItemClickListener()，但我尝试的所有内容都无效。详细信息活动包含三个TextView（名称，姓氏，电话）我所能得到的只是一个错误：

无法将DataProvider强制转换为java.lang.String

如果有其他方法可以做到这一点，请好好告诉我如何做到这一点。

这是DisplayDataActivity.java：

public class DisplayDataActivity extends AppCompatActivity {


ListView listView;
SQLiteDatabase sqLiteDatabase;
UserDbHelper userDbHelper;
Cursor cursor;
ListDataAdapter listDataAdapter;


EditText Search_Last;
String search_Last;

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



    Search_Last = (EditText) findViewById(R.id.searchName);

    // This part of the code is from tutorial
    listView = (ListView) findViewById(R.id.list_view_display);
    listDataAdapter = new ListDataAdapter(getApplicationContext(), R.layout.row_layout);
    listView.setAdapter(listDataAdapter);

    userDbHelper = new UserDbHelper(getApplicationContext());
    sqLiteDatabase = userDbHelper.getReadableDatabase();
    cursor = userDbHelper.getInformations(sqLiteDatabase);
    if (cursor.moveToFirst()) {
        do {

            String name, lastName, phone;
            name = cursor.getString(0);
            lastName = cursor.getString(1);
            phone = cursor.getString(2);
            DataProvider dataProvider = new DataProvider(name, lastName);
            listDataAdapter.add(dataProvider);

        } while (cursor.moveToNext());
    }

    // Opens detailed view when contact is clicked
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {



            TextView entryName = (TextView) findViewById(R.id.entryNameDetail);
            TextView entryLastName = (TextView) findViewById(R.id.entryLastDetail);
            TextView entryPhone = (TextView) findViewById(R.id.entryPhoneDetail);

            String data = (String) parent.getItemAtPosition(position);


            String Name = entryName.getText().toString();
            String Last = entryLastName.getText().toString();
            String Phone = entryPhone.getText().toString();

            Intent modify_intent = new Intent(getApplicationContext(), DetailView.class);
            modify_intent.putExtra("Name", Name);
            modify_intent.putExtra("last", Last);
            modify_intent.putExtra("phone", Phone);

            startActivity(modify_intent);


        }
    });



}

这是DataProvider.java：

public class DataProvider {

private String name;
private String lastName;
private String phone;

public String getLastName() {
    return lastName;
}

public void setLastName(String lastName) {
    this.lastName = lastName;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public DataProvider(String name, String lastName)
{
    this.name = name;
    this.lastName = lastName;


}}

DetailView.java：

public class DetailView extends AppCompatActivity {

TextView entryName, entryLastName, entryPhone;
ImageView entryPhoto;
Cursor cursor;

private DataProvider dataProvider;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_detail_view);




    /* WHEN I RUN THIS PART OF THE CODE, THE NAME TEXTVIEW SHOWS EMPTY
    Bundle data_from_list = getIntent().getExtras();
    String value_in_name = data_from_list.getString("passed key data");
    TextView entryName = (TextView)findViewById(R.id.entryNameDetail);
    entryName.setText(value_in_name);
    */

    /* Running this code throws me an error from above */
    Intent modify_intent = getIntent();
    String s1 = modify_intent.getStringExtra("Name");
    String s2 = modify_intent.getStringExtra("Last");
    String s3 = modify_intent.getStringExtra("Phone");

    entryName = (TextView) findViewById(R.id.entryNameDetail);
    entryLastName = (TextView) findViewById(R.id.entryLastDetail);
    entryPhone = (TextView) findViewById(R.id.entryPhoneDetail);

    entryName.setText(s1);
    entryLastName.setText(s2);
    entryPhone.setText(s3);


    // Adding hardcoded data into TextView for testing purposes
    // WORKING
    //entryName.setText("Test ime");
    //entryLastName.setText("Test PRezime");
    //entryPhone.setText("test telefon");


}}

ListDataAdapter.class：

public class ListDataAdapter extends ArrayAdapter {
List list = new ArrayList();

public ListDataAdapter(Context context, int resource) {
    super(context, resource);
}

static class LayoutHandler
{
    TextView NAME, LASTNAME;

}

@Override
public void add(Object object) {
    super.add(object);
    list.add(object);
}

@Override
public int getCount() {
    return list.size();
}

@Nullable
@Override
public Object getItem(int position) {
    return list.get(position);
}

@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View row = convertView;
    LayoutHandler layoutHandler;
    if(row == null)
    {
        LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        row = layoutInflater.inflate(R.layout.row_layout, parent, false);
        layoutHandler = new LayoutHandler();
        layoutHandler.NAME = (TextView) row.findViewById(R.id.text_user_name);
        layoutHandler.LASTNAME = (TextView) row.findViewById(R.id.text_user_last);
        row.setTag(layoutHandler);

    }
    else
    {
        layoutHandler = (LayoutHandler) row.getTag();


    }
    DataProvider dataProvider = (DataProvider) this.getItem(position);
    layoutHandler.NAME.setText(dataProvider.getName());
    layoutHandler.LASTNAME.setText(dataProvider.getLastName());

    return row;


}}

Answer 1

listDataAdapter.add(dataProvider);

我认为您必须将dataProvider（您要添加到列表中的数据）添加到ArrayList而不是自定义适配器。

而是将自定义适配器与ArrayList和ListView相关联以进行可视化。

Answer 2

为什么需要这条线？

epislon

您没有在任何地方使用该变量，并且该行正在为您提供该错误（可能）。

另外我认为你应该在onItemClick监听器中使用view.findViewById而不仅仅是findViewById。

如何使用onItemClickListener（）将点击的项目数据传递给另一个活动

2 个答案: