无法通过此异常

Question

因此，我在android studio中编写登录和注册代码，让我粘贴到这里:

package com.example.myapplication.database;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.util.Log;
import android.widget.*;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class database extends SQLiteOpenHelper {
    private final static String dbName = "user.db";
    private final static String tableName = "customer";
    private int Id;
    private static final String ID_COL = "ID";
    private static final String NAME_COL = "NAME";
    private static final String EMAIL_COL = "EMAIL";
    private static final String PASS_COL = "PASS";
    private static final String MOBILE_COL = "MOBILE";
    private final static int dbVersion = 3;
    Context context;
    public database(Context context){
        super(context,dbName,null,dbVersion);
        this.context = context;
    }
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase = this.getWritableDatabase();
        String query = "CREATE TABLE IF NOT EXISTS " + tableName + "(" + ID_COL + " VARCHAR(50) PRIMARY KEY," + NAME_COL + " VARCHAR(50)," + EMAIL_COL + " VARCHAR(50)," + PASS_COL + " VARCHAR(50), "+MOBILE_COL+" VARCHAR(50));";
        sqLiteDatabase.execSQL(query);
    }
    public boolean checkAlreadyExists(){
        SQLiteDatabase db = this.getReadableDatabase();
        String check = "SELECT * FROM "+tableName+" WHERE ID ="+Id+";";
        Cursor cursor = db.rawQuery(check,null);
        if(cursor.getCount() > 0){
            cursor.close();
            return true;
        }
        else
        {
            cursor.close();
            return false;
        }
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int i, int i1) {
        db.execSQL("DROP TABLE IF EXISTS "+tableName);
        onCreate(db);
    }
    public void addRecord(String id,String name,String email,String pass){
        SQLiteDatabase sql = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(ID_COL,id);
        values.put(NAME_COL,name);
        values.put(EMAIL_COL,email);
        values.put(PASS_COL,pass);
            if(!checkAlreadyExists()) {
                long res = sql.insert(tableName,null,values);
                if(res==-1) {
                    Toast.makeText(context, "Registration Failed", Toast.LENGTH_SHORT).show();
                }
                else
                {
                    Toast.makeText(context,"You Have Been Registered..//",Toast.LENGTH_LONG).show();
                }
            }
            else
            {
                Toast.makeText(context,"User Already Exists.Please Login.",Toast.LENGTH_LONG).show();
            }
    }
    public boolean login(String loginId,String loginPass){
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(tableName,null,ID_COL+" = ? AND "+PASS_COL+" =? ",new String[]{loginId,loginPass},null,null,null);
        try
        {
            if(cursor.moveToFirst())
                return true;
        }catch(Exception e){
            String message = e.getMessage();
            Log.v("Database.java","login:"+e.getMessage());
        }
        finally {
            cursor.close();
        }
        return false;
    }
}

这是按钮按下的代码：

package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;

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

import com.example.myapplication.database.database;

public class RegisterActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        initializeUI();
    }
    private String id;
    private int Id;
    private String name;
    private String pass;
    private String email;
    private String confirm;
    private String mobile;
    private EditText NAME;
    private EditText PASSWORD;
    private EditText CONFIRMPASSWORD;
    private EditText EMAIL;
    private EditText REGISTER;
    private EditText ID;
    //Below method initializes the UI.
    public void initializeUI(){
        ID = (EditText)findViewById(R.id.registerID);
        NAME = (EditText) findViewById(R.id.registerName);
        PASSWORD = (EditText) findViewById(R.id.registerPassword);
        EMAIL = (EditText) findViewById(R.id.registerEmail);
        CONFIRMPASSWORD = (EditText) findViewById(R.id.registerConfirmPassword);
    }
    //Register process gets called.
    public void buttonPressed(View view){
                database db = new database(RegisterActivity.this);
                id = ID.getText().toString();
                name = NAME.getText().toString();
                email = EMAIL.getText().toString();
                pass = PASSWORD.getText().toString();
                confirm = CONFIRMPASSWORD.getText().toString();
                //Seeing if the password matches.
                if (pass.equals(confirm)) {
                    db.addRecord(id, name, email, pass);
                    ID.setText("");
                    NAME.setText("");
                    EMAIL.setText("");
                    PASSWORD.setText("");
                    CONFIRMPASSWORD.setText("");
                    Intent in = new Intent(RegisterActivity.this,LoginActivity.class);
                    startActivity(in);
                } else {
                    Toast.makeText(RegisterActivity.this, "Password are Incorrect..//", Toast.LENGTH_LONG).show();
                }
            }

}

我得到以下异常：

E/androidRuntime:致命异常:主进程:com.example.myapplication，PID:3980 Java . lang . illegalstateexception:无法执行Android的方法:onClick at Android x . app compat . app . appcompatviewinflater＄declaredonclicklistener . onClick(appcompatviewinflater . Java:446)at Android . view . view . perform click(view . Java:5610)at com . Google . Android . material . button . material button . perform click(material button . Java:1133

Answer 1

您应该始终查找异常的原因部分：

Caused by: java.lang.IllegalStateException: getDatabase called recursively
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:203)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
at com.example.myapplication.database.database.onCreate(database.java:28) at

您正在SQLiteOpenHelper的onCreate（）方法中调用getWritableDatabase（）。不要这样做-改用传递给您的onCreate（）方法的sqLiteDatabase：

@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
    String query = "CREATE TABLE IF NOT EXISTS " + tableName + "(" + ID_COL + " VARCHAR(50) PRIMARY KEY," + NAME_COL + " VARCHAR(50)," + EMAIL_COL + " VARCHAR(50)," + PASS_COL + " VARCHAR(50), "+MOBILE_COL+" VARCHAR(50));";
    sqLiteDatabase.execSQL(query);
}