查詢不使用 DAO 訪問 Room 數據庫，沒有錯誤

Question

嘿，我是 Android 的新手，還在學習。 我正在為大學做一個項目。 我想做的是使用 Room 的登錄/注冊系統。

注冊頁面工作正常，生成數據庫並包含任何新用戶。 我的問題是當我在登錄頁面上檢查現有用戶時。

按下登錄按鈕后，如果必須執行查詢，應用程序就會停止工作。 Profiler 說應用程序崩潰了，即使我仍然可以導航它。

我在 logcat 或 Run 中沒有錯誤。 請告訴我訪問數據庫時我做錯了什么。 如果我能看到至少一個錯誤，我就能解決問題。

這是 java 文件

RegisterActivity.java

package com.example.spacetrt40;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.example.spacetrt40.EntityClass.UserModel;

public class RegisterActivity extends AppCompatActivity {

    EditText  name,phone,password,email;
    Button save,getData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        name=findViewById(R.id.etName);
        email=findViewById(R.id.etMail);
        phone=findViewById(R.id.etPhone);
        password=findViewById(R.id.etPassword);
        save=findViewById(R.id.btnReg2);
        save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                sendData();
            }
        });
    }

    private void sendData() {
        String name_txt = name.getText().toString().trim();
        String phone_txt = phone.getText().toString().trim();
        String email_txt = email.getText().toString().trim();
        String password_txt = password.getText().toString().trim();
        UserModel model = new UserModel();
        model.setName(name_txt);
        model.setEmail(email_txt);
        model.setPassword(password_txt);
        model.setPhone(phone_txt);
        DatabaseClass.getDatabase(getApplicationContext()).getDao().insertAllData(model);

        Toast.makeText(this, "Data Successfully Saved", Toast.LENGTH_SHORT).show();
    }

    }

DatabaseClass.java

package com.example.spacetrt40;


import android.content.Context;

import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;

import com.example.spacetrt40.EntityClass.UserModel;

@Database(entities = {UserModel.class}, version = 1,exportSchema = false)
public abstract class DatabaseClass extends RoomDatabase {
    public abstract DaoClass getDao();

    private static DatabaseClass instance;



    static DatabaseClass getDatabase(final Context context){
        if (instance==null){
            synchronized (DatabaseClass.class){
                instance = Room.databaseBuilder(context, DatabaseClass.class, "DATABASE").allowMainThreadQueries().fallbackToDestructiveMigration().build();


            }
        }
        return instance;
    }

}

UserModel.java

import androidx.annotation.NonNull;
import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

@Entity(tableName = "user")
public class UserModel {

    public void setKey(int key) {
        this.key = key;
    }

    @PrimaryKey(autoGenerate = true)
    @NonNull

    private int key;


    @ColumnInfo(name = "name")
    private String name;



    @ColumnInfo(name = "email")
    private String email;



    @ColumnInfo(name = "phone")
    private String phone;

    @ColumnInfo(name = "password")
    private String password;

    public int getKey() {
        return key;
    }


    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;

    }
    public String getName() {
        return name;
    }

    public String getPhone() {
        return phone;
    }

    public String getPassword() {
        return password;
    }



    public void setName(String name) {
        this.name = name;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

DaoClass.java

package com.example.spacetrt40;


import androidx.room.Dao;
import androidx.room.Insert;
import androidx.room.Query;

import com.example.spacetrt40.EntityClass.UserModel;

import java.util.List;

@Dao
public interface DaoClass {

    @Insert
    void insertAllData(UserModel model);
    //Select All Data
    @Query("select * from  user")
    List<UserModel> getAllData();


    @Query("SELECT * from user where email=(:email) and password=(:password)")
    UserModel login(String email,String password);



}

LoginActivity.java

package com.example.spacetrt40;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import android.widget.Toast;

import com.example.spacetrt40.EntityClass.UserModel;

public class LoginActivity extends AppCompatActivity {

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

        EditText user = findViewById(R.id.etUser);
        EditText password = findViewById(R.id.etPass);
        Button login = findViewById(R.id.button3);





        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String emailText = user.getText().toString();
                String passwordText=password.getText().toString();
                if (emailText.isEmpty()||passwordText.isEmpty()){
                    Toast.makeText(getApplicationContext(),"Fill in all Fields",Toast.LENGTH_LONG).show();

                }else{
                    //perform query
                    DatabaseClass userDatabase = DatabaseClass.getDatabase(getApplicationContext());
                    new Thread(new Runnable() {
                        @Override
                        public void run() {
                            DaoClass daoClass = userDatabase.getDao();
                            new Thread((new Runnable() {
                                @Override
                                public void run() {
                                    UserModel userModel= daoClass.login(emailText,passwordText);
                                    if (userModel==null){
                                        runOnUiThread(new Runnable() {
                                            @Override
                                            public void run() {
                                                Toast.makeText(getApplicationContext(),"Invalid Credentials",Toast.LENGTH_LONG).show();
                                            }
                                        });
                                    }else{
                                        Intent in=new Intent(LoginActivity.this,MainActivity.class);
                                        startActivity(in);


                                    }
                                }
                            }));
                        }
                    }).start();
                }

            }
        });
    }





    public void sendToReg(View v){
        Button reg = findViewById(R.id.btnReg);
        Intent in = new Intent(this, RegisterActivity.class);
        startActivity(in);
    }

}

如果需要，我將提供任何其他信息。

Answer 1

我相信您當前的問題是您試圖在可運行的內部運行可運行而不啟動內部可運行。

查詢很好，只是不需要 arguments（電子郵件和密碼）周圍的括號。 以下會很好： -

@Query("SELECT * from user where email=:email and password=:password")
UserModel login(String email,String password);

關於當前問題，您可能會發現在LoginActivity中對登錄按鈕的onClickListener使用以下內容會使您繼續前進：-

    login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String emailText = user.getText().toString();
            String passwordText=password.getText().toString();
            if (emailText.isEmpty()||passwordText.isEmpty()){
                Toast.makeText(getApplicationContext(),"Fill in all Fields",Toast.LENGTH_LONG).show();

            }else{
                //perform query
                DatabaseClass userDatabase = DatabaseClass.getDatabase(getApplicationContext());
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        DaoClass daoClass = userDatabase.getDao();
                        UserModel userModel= daoClass.login(emailText,passwordText);
                        if (userModel==null){
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(getApplicationContext(),"Invalid Credentials",Toast.LENGTH_LONG).show();
                                }
                            });
                        }else{
                            Intent in=new Intent(LoginActivity.this,MainActivity.class);
                            startActivity(in);
                        }
                    }
                }).start();
            }
        }
    });

即只是一個可運行的。