android studio从Sqlite数据库中检索数据并将其显示到textview中 [英] android studio retrieve data from Sqlite database and display it into textview
问题描述
大家好,我需要你的帮助。我在我的应用程序中创建SQLite数据库,然后将数据插入其中。现在我想从中检索数据,但我只想插入一个数据并检索它然后将其显示到TextView中。
Hi guys please I need your help. I create SQLite Database in my app and I insert the data into it. And now I want to retrieve data from it but I want just insert one data and retrieve it then display it into a TextView.
请帮助我们这是我第一次我使用SQLite数据库。
please help me guys this is my first time I use SQLite Database.
public class Db_sqlit extends SQLiteOpenHelper{
String TABLE_NAME = "BallsTable";
public final static String name = "db_data";
public Db_sqlit(Context context) {
super(context, name, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table "+TABLE_NAME+" (id INTEGER PRIMARY KEY AUTOINCREMENT, ball TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
onCreate(db);
}
public boolean insertData(String balls){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("ball",balls);
long result = db.insert(TABLE_NAME,null,contentValues);
if(result == -1){
return false;
}
else
return true;
}
public void list_balls(TextView textView) {
Cursor res = this.getReadableDatabase().rawQuery("select ball from "+TABLE_NAME+"",null);
textView.setText("");
while (res.moveToNext()){
textView.append(res.getString(1));
}
}
}
推荐答案
以下是我如何实现这一目标的一个例子。
Here is a example of how I achieved this.
在这个例子中,我将 store
,检索
,更新
和删除
学生姓名和年龄。
In this example I will store
, retrieve
, update
and delete
a students name and age.
首先创建一个类,我称之为
First create a class, I called mine
DBManager.java
public class DBManager {
private Context context;
private SQLiteDatabase database;
private SQLiteHelper dbHelper;
public DBManager(Context c) {
this.context = c;
}
public DBManager open() throws SQLException {
this.dbHelper = new SQLiteHelper(this.context);
this.database = this.dbHelper.getWritableDatabase();
return this;
}
public void close() {
this.dbHelper.close();
}
public void insert(String name, String desc) {
ContentValues contentValue = new ContentValues();
contentValue.put(SQLiteHelper.NAME, name);
contentValue.put(SQLiteHelper.AGE, desc);
this.database.insert(SQLiteHelper.TABLE_NAME_STUDENT, null, contentValue);
}
public Cursor fetch() {
Cursor cursor = this.database.query(SQLiteHelper.TABLE_NAME_STUDENT, new String[]{SQLiteHelper._ID, SQLiteHelper.NAME, SQLiteHelper.AGE}, null, null, null, null, null);
if (cursor != null) {
cursor.moveToFirst();
}
return cursor;
}
public int update(long _id, String name, String desc) {
ContentValues contentValues = new ContentValues();
contentValues.put(SQLiteHelper.NAME, name);
contentValues.put(SQLiteHelper.AGE, desc);
return this.database.update(SQLiteHelper.TABLE_NAME_STUDENT, contentValues, "_id = " + _id, null);
}
public void delete(long _id) {
this.database.delete(SQLiteHelper.TABLE_NAME_STUDENT, "_id=" + _id, null);
}
}
然后创建 SQLiteOpenHelper
我打电话给我了
Then create a SQLiteOpenHelper
I called mine
SQLiteHelper.java
public class SQLiteHelper extends SQLiteOpenHelper {
public static final String AGE = "age";
private static final String CREATE_TABLE_STUDENT = " create table STUDENTS ( _id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL , age TEXT );";
private static final String DB_NAME = "STUDENTS.DB";
private static final int DB_VERSION = 1;
public static final String NAME = "name";
public static final String TABLE_NAME_STUDENT = "STUDENTS";
public static final String _ID = "_id";
public SQLiteHelper(Context context) {
super(context, DB_NAME, null, 1);
}
public void onCreate(SQLiteDatabase db) {
Log.e("SQLITE", "table reated");
db.execSQL(CREATE_TABLE_STUDENT);
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS STUDENTS");
onCreate(db);
}
}
要添加:
在此示例中,我从 EditText
并且当单击按钮时,我检查 EditText
是否为空。如果它不是空的并且学生尚不存在,我将学生姓名和年龄插入数据库。我显示 Toast
,让用户知道状态:
In this example I take the text from EditText
and when the button is clicked I check if the EditText
is empty or not. If it is not empty and the student doesn't already exist I insert the students name and age into the database. I display a Toast
, letting the user know of the status:
btnAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (edtName.getText().toString().trim().length() == 0) {
Toast.makeText(getApplicationContext(), "Please provide your students name", Toast.LENGTH_SHORT).show();
} else
try {
if (edtAge.getText().toString().trim().length() != 0) {
String name = edtName.getText().toString().trim();
String age = edtAge.getText().toString().trim();
String query = "Select * From STUDENTS where name = '"+name+"'";
if(dbManager.fetch().getCount()>0){
Toast.makeText(getApplicationContext(), "Already Exist!", Toast.LENGTH_SHORT).show();
}else{
dbManager.insert(name, age);
Toast.makeText(getApplicationContext(), "Added successfully!", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(getApplicationContext(), "please provide student age!", Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
e.printStackTrace();
}
}
});
更新:
这里我将 EditText
中的文本带到单击按钮时更新学生。您还可以将以下内容放在 try / catch
中,以确保它已成功更新。
TO UPDATE:
Here I take the Text in EditText
and update the student when the button is clicked. You can also place the following in a try/catch
to make sure it is updated successfully.
btnupdate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String name = nameText.getText().toString();
String age = ageText.getText().toString();
dbManager.update(_id, name, age);
Toast.makeText(getApplicationContext(), "Updated successfully!", Toast.LENGTH_SHORT).show();
}
});
要删除:
dbManager.delete(_id);
Toast.makeText(getApplicationContext(), "Deleted successfully!", Toast.LENGTH_SHORT).show();
获取:
在这里,我得到学生的名字并将其显示在 TextView
Here I get the name of the student and display it in a TextView
DBManager dbManager = new DBManager(getActivity());
dbManager.open();
Cursor cursor = dbManager.fetch();
cursor.moveToFirst();
final TextView studentName = (TextView) getActivity().findViewById(R.id.nameOfStudent);
studentName.settext(cursor.getString(0));
这篇关于android studio从Sqlite数据库中检索数据并将其显示到textview中的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!