我的 Sqlite To Listview 有什么问题，它没有显示所需的结果 [重复]

Question

我正在尝试从 DB 中获取所有 ID 和 IncomeCategoryName 并将它们放入列表视图中。

问题是显示的是Package Name. ClassName@hexcode，而不是ID 和IncomeCategory Name。

类文件

public class IncomeCategoriesClass {
    private Integer CATEGORY_ID;
    private String CATEGORY_NAME;

    public IncomeCategoriesClass(Integer CATEGORY_ID, String CATEGORY_NAME) {
        this.CATEGORY_ID = CATEGORY_ID;
        this.CATEGORY_NAME = CATEGORY_NAME;
    }

    public IncomeCategoriesClass() {
        this.CATEGORY_NAME = CATEGORY_NAME;
    }

    public Integer getCATEGORY_ID() {
        return CATEGORY_ID;
    }

    public void setCATEGORY_ID(Integer CATEGORY_ID) {
        this.CATEGORY_ID = CATEGORY_ID;
    }

    public String getCATEGORY_NAME() {
        return CATEGORY_NAME;
    }

    public void setCATEGORY_NAME(String CATEGORY_NAME) {
        this.CATEGORY_NAME = CATEGORY_NAME;
    }
}

数据库助手 sn-p

公共列表 get_AllIncomeCategories(){ 列出所有收入类别 = 新的 LinkedList(); 字符串 queryString = "选择 * FROM " + INCOME_CATEGORIES_TABLE; SQLiteDatabase db = this.getReadableDatabase(); 光标 cursor = db.rawQuery(queryString,null);

    IncomeCategoriesClass incomeCategoriesClass;
    if(cursor.moveToFirst()){
        do {
            incomeCategoriesClass = new IncomeCategoriesClass();
            incomeCategoriesClass.setCATEGORY_ID(Integer.parseInt(cursor.getString(0)));
            incomeCategoriesClass.setCATEGORY_NAME(cursor.getString(1));
            AllIncomeCategories.add(incomeCategoriesClass);
        }while (cursor.moveToNext());
        }
    cursor.close();
    db.close();
    return AllIncomeCategories;
}

AddEditincomeCategoriesActivity

public class AddEditIncomeCategoriesActivity extends AppCompatActivity {

    //Define Screen Fields And Variables
    ListView listviewAllIncomeCategories;


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

        //Initialize Screen Field Variables
        btn_ViewAllIncomeCategory = findViewById(R.id.btn_ViewAllIncomeCategory);
        listviewAllIncomeCategories = findViewById(R.id.listviewAllIncomeCategories);


        //View All Income Categories on Button Click
        btn_ViewAllIncomeCategory.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                DataBaseHelper dataBaseHelper = new DataBaseHelper(AddEditIncomeCategoriesActivity.this);
                List<IncomeCategoriesClass> AllIncomeCategories;
                AllIncomeCategories = dataBaseHelper.get_AllIncomeCategories();
                ArrayAdapter adapter = new ArrayAdapter(AddEditIncomeCategoriesActivity.this,android.R.layout.simple_list_item_1,AllIncomeCategories);
                listviewAllIncomeCategories.setAdapter(adapter);
            }
        });

        //Add Income Category on Button Click
    }
}

它正在输出数据但不是我要查找的数据，它是 Packagename.Class@HexCode 而不是 1 个现金、2 个信用卡等。

我做错了什么，我该如何正确地做到这一点？

Answer 1

Simple ArrayAdapter 只能膨胀平面值，如字符串或整数。对于对象列表，您需要一个自定义适配器来呈现您的视图。

有关实施细节，请参阅ListView Android。

Answer 2

您看到的是Object#toString() 的输出。

您可以覆盖 IncomeCategoriesClass 中的 toString() 以生成您希望为该项目显示的字符串输出。