Question

这是我的sqlite数据库代码

public void onCreate(SQLiteDatabase db) {
        String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_USER + "("
                + KEY_ID + " INTEGER PRIMARY KEY,"+ SERVER_ID + " TEXT,"+ ACCESS_TOKEN + " TEXT," + FIRST_NAME
                + " TEXT," + LAST_NAME + " TEXT," + USER_EMAIL + " TEXT,"
                + USERNAME + " TEXT," + ADDRESS + " TEXT," + LATITUDE + " TEXT,"
                + LONGITUDE + " TEXT," + BLOOD_GROUP + "  TEXT," + GENDER + " TEXT,"
                + PHONE_NUMBER + " TEXT," + MOBILE_NUMBER + " TEXT," + DOB_YEAR + " TEXT,"
                + DOB_MONTH + " TEXT," + DOB_DAY + " TEXT," + COUNTRY + " TEXT," + IMAGE_URL
                + "  TEXT," + TYPE + " TEXT" +");";
        db.execSQL(CREATE_LOGIN_TABLE);

这是我从表中获取所有值的代码

 public HashMap<String, String> getBPositiveData(){
        HashMap<String, String> getData = new HashMap<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from user where type =? and blood_group =?", new String[]{"friends", "B_plus"});
        //Move to first
       if (cursor.moveToFirst()){

           do {
                   getData.put("server_id", cursor.getString(1));
                   getData.put("first_name", cursor.getString(3));
                   getData.put("last_name", cursor.getString(4));
                   getData.put("blood_group", cursor.getString(10));
                   getData.put("mobile_number", cursor.getString(13));
                   getData.put("imageURL", cursor.getString(18));
                   cursor.moveToNext();
               int abc = cursor.getCount();
               Log.e("cursorCount", String.valueOf(abc));
           }while (!cursor.isAfterLast());
           cursor.close();
        }
        return getData;
    }

在我的数据库中，所有行都已正确插入，查询也为我提供了所需的数据（我从genymotion模拟器中检查了数据库，因此我确信数据存在于那里）。我的问题是我只从该表的最后一行获取值。谁能告诉我，我在这里做错了什么？我用来检索活动中的值的代码是：

HashMap<String, String> profile = db.getBPositiveData();
                final String fname = profile.get("first_name");
                final String lname = profile.get("last_name");
                final String bgroup = profile.get("blood_group");
                final String mnumber = profile.get("mobile_number");
                final String iurl = profile.get("imageURL");

提前谢谢你。

Answer 1

尝试你的＆＃34; if（cursor.moveToFirst（））＆＃34;作为＆＃34; while（cursor.next（）＆＃34;循环并在循环中返回你的getData。

我在谈论的一个例子可以在adding data to hashmap from database中看到。

Answer 2

对于每次迭代，你都会在Hashmap中覆盖你的dara。例如，您只能有一个键“server_id”。对于您的代码放置的第一条记录

getData.put（“server_id”，cursor.getString（1））;
当您拨打

时的第二条记录

getData.put（“server_id”，cursor.getString（1））;
它覆盖了。

Answer 3

创建一个新类User

公共类用户{

String first_name;
String last_name;
String blood_group;
// ...the rest of the propertied
}

更改getData的HashMap声明

HashMap userList = new HashMap＆lt;＆gt;（）;

然后修改代码

User currentUser = null;
if(cursor.moveToFirst())
{

    do {
        currentUser = new User();
        currentUser.first_name = cursor.getString(3);
        currentUser.last_name = cursor.getString(4);
        currentUser.blood_group = cursor.getString(10);
        // the rest of your data for user
        String rowKey = cursor.getString(cursor.getColumnIndexOrThrow("_id"));
        userList.put(rowKey, currentUser);
        cursor.moveToNext();

        // the rest of your code

    } while (!cursor.isAfterLast());
    cursor.close();
    return userList;
}

然后相应地将方法的返回类型从HashMap更改为HashMap。

如果这对您有用，请告诉我

Answer 4

首先，你需要创建你的对象类，例如。 User

public class User {

    private String firstName;

    private String lastName;

    private String bloodGroup;

    private String mobileNumber;

    private String imageUrl;

    public User() {

    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

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

    public String getBloodGroup() {
        return bloodGroup;
    }

    public void setBloodGroup(String bloodGroup) {
        this.bloodGroup = bloodGroup;
    }

    public String getMobileNumber() {
        return mobileNumber;
    }

    public void setMobileNumber(String mobileNumber) {
        this.mobileNumber = mobileNumber;
    }

    public String getImageUrl() {
        return imageUrl;
    }

    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl;
    }
}

然后为用户提供B-positive用户：

public List<User> getBPositiveUsers() {
    List<User> users = new ArrayList<>();

    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery("select * from user where type =? and blood_group =?", new String[]{"friends", "B_plus"});

    try {
        if (cursor.moveToFirst()) {
            do {
                User user = new User();

                user.setFirstName(cursor.getString(3));
                user.setLastName(cursor.getString(4));
                user.setBloodGroup(cursor.getString(10));
                user.setMobileNumber(cursor.getString(13));
                user.setImageUrl(cursor.getString(18));

                users.add(user);
            } while(cursor.moveToNext());
        }
    } catch (Exception e) {
        Log.d("ERROR", "Error while trying to get users from database");
    } finally {
        if (cursor != null && !cursor.isClosed()) {
            cursor.close();
        }
    }

    return users;
}

使用光标时，try-catch-finally块总是很好。
user.setFirstName(cursor.getString(3));使用起来很丑陋。如果您将列名称作为常量（我假设您正在使用它，因为在创建时使用ex。FIRST_NAME），如果您更改此行并且其他类似于user.setFirstName(cursor.getString(cursor.getColumnIndex(FIRST_NAME)));
检查Lombok是否为变量创建getter和setter。它使代码更容易阅读：）

仅显示sqlite数据库的最后一行

4 个答案: