预填充的SQLite数据库在Android Studio中无法正常阅读 [英] Pre-populated SQLite Database not reading properly in Android Studio
问题描述
我是新到StackOverflow所以我不知道这是如何工作，但我真的需要一些帮助这个应用程序我在Android Studio中构建。我有一个预填充的chemicals.sqlite数据库，我试图在Android Studio中搜索。基本上，我设计的应用程序将允许用户按名称搜索复合，它将显示有关它的信息。由于某种原因，我的程序说，它不能显示任何值，我试图在应用程序的模拟器搜索。
I'm new to StackOverflow so I'm not sure how this works, but I really need some help with this app I'm building in Android Studio. I have a pre-populated chemicals.sqlite database that I am trying to search through in Android Studio. Basically, the app I'm designing is going to allow a user to search for a compound by name and it will display information about it. For some reason, my program is saying that it can't display any of the values that I'm trying to search in the app's emulator. It just always shows the "No Match Found".
这是我的DatabaseHelper类：
Here is my DatabaseHelper class:
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "chemicals.sqlite";
private static final String TABLE_OSHA = "osha";
public static final String COLUMN_COMPOUND = "compound";
public static final String COLUMN_H = "h";
public static final String COLUMN_F = "f";
public static final String COLUMN_R = "r";
public static final String COLUMN_SN = "sn";
public DataBaseHelper(Context context, String name,
SQLiteDatabase.CursorFactory factory, int version) {
super(context, DATABASE_NAME, factory, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_OSHA_TABLE = "CREATE TABLE " +
TABLE_OSHA + "("
+ COLUMN_COMPOUND + " TEXT," + COLUMN_H
+ " TEXT," + COLUMN_F + " TEXT," + COLUMN_R + " TEXT," + COLUMN_SN + " TEXT" + ")";
db.execSQL(CREATE_OSHA_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_OSHA);
onCreate(db);
}
public Compound findCompound(String compoundname) {
String query = "Select * FROM " + TABLE_OSHA + " WHERE " + COLUMN_COMPOUND + "= '" + compoundname + "'";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query, null);
Compound compound = new Compound();
if (cursor.moveToFirst()) {
cursor.moveToFirst();
compound.setH(cursor.getString(0));
compound.setF(cursor.getString(1));
compound.setR(cursor.getString(2));
compound.setSN(cursor.getString(3));
// cursor.moveToNext();
cursor.close();
} else {
compound = null;
}
db.close();
return compound;
}
}
这是我的复合类：
public class Compound {
private String _compound;
private String _h;
private String _f;
private String _r;
private String _sn;
public Compound() {
}
public Compound(String compound, String h, String f, String r, String sn) {
this._compound = compound;
this._h = h;
this._f = f;
this._r = r;
this._sn = sn;
}
public Compound(String h, String f, String r, String sn) {
this._h = h;
this._f = f;
this._r = r;
this._sn = sn;
}
public void setCompound(String compound) {
this._compound = compound;
}
public String getCompound() {
return this._compound;
}
public void setH(String h) {
this._h = h;
}
public String getH() {
return this._h;
}
public void setF(String f) {
this._f = f;
}
public String getF() {
return this._f;
}
public void setR(String r) {
this._r = r;
}
public String getR(){
return this._r;
}
public void setSN(String sn){
this._sn = sn;
}
public String getSN(){
return this._sn;
}
}
这里是我的主类：
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class oshaSearch extends AppCompatActivity {
TextView txtH;
TextView txtR;
TextView txtF;
TextView txtSN;
EditText txtCompound;
Button btnSearch;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_osha_search);
txtF = (TextView) findViewById(R.id.txtF);
txtR = (TextView) findViewById(R.id.txtR);
txtH = (TextView) findViewById(R.id.txtH);
txtSN = (TextView) findViewById(R.id.txtSN);
txtCompound = (EditText) findViewById(R.id.searchCompound);
btnSearch = (Button) findViewById(R.id.btnSearch);
}
public void lookupCompound (View view) {
DataBaseHelper dbHandler = new DataBaseHelper(this, null, null, 1);
Compound compound =
dbHandler.findCompound(txtCompound.getText().toString());
if (compound != null) {
txtH.setText(String.valueOf(compound.getH()));
txtF.setText(String.valueOf(compound.getF()));
txtR.setText(String.valueOf(compound.getR()));
txtSN.setText(String.valueOf(compound.getSN()));
} else {
txtH.setText("No Match Found");
}
}
}
任何所有帮助赞赏。请帮助我。
附加信息：数据库在assets文件夹中，数据库中的所有值都是文本字段，用户正在按复合名称搜索，数据库具有.sqlite扩展名。
Any and all help is greatly appreciated. Please help me out. Additional information: The database is in the assets folder, All values in the database are text fields, The user is searching by compound name, The database has a .sqlite extension. Thank you all in advanced.
推荐答案
您首先需要检查数据库是否正确创建，对于
you first need to check if database is properly created or not, for that
public DataBaseHelper(Context context) {
super(context, Environment.getExternalStorageDirectory()+"/"+DATABASE_NAME, null, 1);
}
使用此构造函数，这将会将您的应用数据库保存在手机的外部存储中。
之前，给清单文件中的外部存储权限。
并使用来自google play store的sqliteManager应用程序来检查数据库结构。
use this constructor , this will save your app database in external storage of your phone. before that give permission to external storage in manifest file. and use sqliteManager application from google play store to check database structure.
或者你可以使用stetho调试android的数据库。
参考链接： http：/ /code.tutsplus.com/tutorials/debugging-android-apps-with-facebooks-stetho--cms-24205
Or you can use stetho to debug database of android. reference link:http://code.tutsplus.com/tutorials/debugging-android-apps-with-facebooks-stetho--cms-24205
这篇关于预填充的SQLite数据库在Android Studio中无法正常阅读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！
