由于未解析的字符串，无法将字符串数据从 dialogfragment 传输到 SQL 数据库

问：

我想让一个dialogfragment从用户那里获取联系人姓名和号码，并将其保存在sqLite数据库中，我可以使用该数据库在主活动中显示为卡片视图。 我尝试按照本教程了解如何拥有多个列条目并将它们添加到数据库中。

这是 addcontact dialogfragment 的代码

package com.example.rakshakmk1;

import android.app.Dialog;
import android.content.DialogInterface;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.fragment.app.DialogFragment;

public class Dialog_AddContact extends DialogFragment  {
DatabaseHelper myDB;

@Override
public void onStart() {
    super.onStart();

    // safety check
    if (getDialog() == null) {
        return;
    }

    // set the animations to use on showing and hiding the dialog
    getDialog().getWindow().getAttributes().windowAnimations = R.style.DialogAnimation;
    // alternative way of doing it
    //getDialog().getWindow().getAttributes().
    //    windowAnimations = R.style.dialog_animation_fade;

    // ... other stuff you want to do in your onStart() method
}


private static final String TAG = "Dialog_AddContact";
public Dialog_AddContact() {
}
public void AddData(String newName,String newNumber){
    boolean insertData = myDB.addData(newName,newNumber);
    if(insertData==true){
        Toast.makeText(getContext(),"Contact Added Successfully",Toast.LENGTH_SHORT).show();
    }
    else{
        Toast.makeText(getContext(),"Contact not Added",Toast.LENGTH_SHORT).show();
    }
}

public Dialog_AddContact(View source) {
    this.source = source;
}

//widgets
private EditText etName,etPhonenumber ;
private Button btnEnterContact, btnCancel1;
private View source;

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.dialog_addcontact,container,false);

    Window window = getDialog().getWindow();

    // set "origin" to top left corner, so to speak
    window.setGravity(Gravity.TOP|Gravity.LEFT);

    // after that, setting values for x and y works "naturally"
    WindowManager.LayoutParams params = window.getAttributes();
    params.x = 50;
    params.y = 1000;
    window.setAttributes(params);
    Log.d(TAG, String.format("Positioning DialogFragment to: x %d; y %d", params.x, params.y));

    //for rounded corners
    if (getDialog() != null && getDialog().getWindow() != null) {
        getDialog().getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        getDialog().getWindow().requestFeature(Window.FEATURE_NO_TITLE);
    }
    btnCancel1 = view.findViewById(R.id.btnCancel1);
    btnEnterContact = view.findViewById(R.id.btnEnterContact);
    etName =   view.findViewById(R.id.etName);
    etPhonenumber = view.findViewById(R.id.etNumber);

    btnCancel1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Log.d(TAG, "onClick: Closing Dialog");
            getDialog().dismiss();
        }
    });
    btnEnterContact.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Log.d(TAG, "onClick: Entering Contact");
            if(etName.length() == 0)
            {
                getDialog().dismiss();
                Toast.makeText(getContext(),"Invalid Name",Toast.LENGTH_SHORT).show();
            }
            else
            {

                Toast.makeText(getContext(),"Contact Added",Toast.LENGTH_SHORT).show();
                String name = etName.getText().toString();
                getDialog().dismiss();
            }
            if(etPhonenumber.length() == 0)
            {
                getDialog().dismiss();
                Toast.makeText(getContext(),"Invalid Number",Toast.LENGTH_SHORT).show();
            }
            else
            {

                Toast.makeText(getContext(),"Contact Added",Toast.LENGTH_SHORT).show();
                String number = etPhonenumber.getText().toString();
                getDialog().dismiss();
            }
            if(etName.length()!=0 && etPhonenumber.length()!=0){
                AddData(newName,newNumber);
            }
            else {
                Toast.makeText(getContext(),"Invalid Entries",Toast.LENGTH_SHORT).show();
            }

        }
    });
    return view;
}
}

这是 sqLite 数据库助手的代码

package com.example.rakshakmk1;

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

import androidx.annotation.Nullable;

import static android.content.ContentValues.TAG;

public class DatabaseHelper extends SQLiteOpenHelper {
 public static final String DATABASE_NAME = "contactlist.db";
 public static final String TABLE_NAME = "contactlist_data";
 public static final String COL1 = "ID";
 public static final String COL2 = "NAME";
 public static final String COL3 = "NUMBER";



public DatabaseHelper(@Nullable Context context){super(context,DATABASE_NAME,null,1);}

@Override
public void onCreate(SQLiteDatabase db) {
    String createTable = "CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, " +
            "NAME TEXT,NUMBER TEXT)";
    db.execSQL(createTable);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w(TAG,"Upgrading database from version"+oldVersion+"to"+ newVersion + ",which will destroy all old data");
    //db.execSQL("DROP_IF_TABLE_EXISTS" + TABLE_NAME);
    onCreate(db);
}

public boolean addData(String newName,String newNumber) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL2, newName);
    contentValues.put(COL3,newNumber);

    long result = db.insert(TABLE_NAME, null, contentValues);

    //if date as inserted incorrectly it will return -1
    if (result == -1) {
        return false;
    } else {
        return true;
    }
}
public Cursor getListContents(){
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor data = db.rawQuery("SELECT * FROM " + TABLE_NAME, null);
    return data;
}
}

目前，即使我已经在databasehelper中定义了它，我也收到此错误

我似乎无法弄清楚为什么我无法从片段中获取这些字符串值的原因，而它在教程视频中似乎可以完美运行。

任何和所有的帮助将不胜感激