我已经建立了一个 SQLite 数据库,该数据库在创建我需要的表方面运行良好。我现在一直在尝试做的是从另一个类(Signup.java)插入数据库。我想抓取 edittext 中的文本输入并将其插入数据库,但仅限于单击按钮时。
请参阅下面的 DatabaseHelper 类:
package com.example.testerrquin.euro2016fanguide;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "Euro2016.db";
public static final String TABLE_USERS = "Users_table";
public static final String TABLE_CAPACITY = "Capacity_table";
public static final int CapacityOne = 1;
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
SQLiteDatabase db = this.getWritableDatabase();
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Create table " + TABLE_USERS +" (UserID INTEGER PRIMARY KEY AUTOINCREMENT, Forename TEXT, Surname TEXT, Email TEXT, Password TEXT, Country TEXT)");
db.execSQL("Create table " + TABLE_CAPACITY +" (CapacityID INTEGER PRIMARY KEY AUTOINCREMENT, Capacity INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_USERS);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CAPACITY);
onCreate(db);
}
}
基本上我需要运行以“db.execSQL”开头的行。我可能需要在某个地方引用“db”来链接到 Databasehelper 类,但不确定。目前我收到“无法解析符号'db'”。
CompleteB.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String grabFirstname = UsernameET.getText().toString();
String grabSurname = SurnameET.getText().toString();
String grabEmail = EmailET.getText().toString();
String grabPassword = PasswordET.getText().toString();
String grabCountry = CountryDrop.getSelectedItem().toString();
db.execSQL("Insert into Users_table (Forename, Surname, Email, Password, Country) values ((" + grabFirstname +"),(" + grabSurname +"),(" + grabEmail +"), (" + grabPassword +"), (" + grabCountry +"))");
Intent i=new Intent(Signup.this,Login.class);
startActivity(i);
}
});
提前致谢。
最佳答案
在 SQL 帮助器类中声明您需要的任何方法:
public void sampleMethod(String[] arguments) {
ContentValues values = new ContentValues();
values.put("Column1", arguments[0]);
values.put("Column2", arguments[1]);
values.put("Column3", arguments[2]);
....
db.insert(TABLE_NAME, null, values);
}
在您的 Activity 中:
@Override
public void onClick(View v) {
String grabFirstname = UsernameET.getText().toString();
String grabSurname = SurnameET.getText().toString();
String grabEmail = EmailET.getText().toString();
String grabPassword = PasswordET.getText().toString();
String grabCountry = CountryDrop.getSelectedItem().toString();
DatabaseHelper helper = new DatabaseHelper(context); //replace context with your activity context. "this" would refer to your onClickListener so be careful.
helper.sampleMethod(new String[]{
"user",
"pass",
"foo",
"bar",
...
});
//rest of your code
}
另外,请确保在使用完数据库后将其关闭。我个人会在每个方法中调用 getWritableDatabase,然后在方法结束时关闭数据库。像这样的东西:
public class DatabaseHelper extends SQLiteOpenHelper {
Context c;
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
c = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Create table " + TABLE_USERS +" (UserID INTEGER PRIMARY KEY AUTOINCREMENT, Forename TEXT, Surname TEXT, Email TEXT, Password TEXT, Country TEXT)");
db.execSQL("Create table " + TABLE_CAPACITY +" (CapacityID INTEGER PRIMARY KEY AUTOINCREMENT, Capacity INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_USERS);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CAPACITY);
onCreate(db);
}
public void sampleMethod(String[] arguments) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("Column1", arguments[0]);
values.put("Column2", arguments[1]);
values.put("Column3", arguments[2]);
....
db.insert(TABLE_NAME, null, values);
db.close();
}
关于java - Android如何在数据库帮助器类之外将数据插入数据库,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35989271/