如何将从SQLiteDatabase检索到的列的值逐个转换为字符串？

Question

该应用程序用于存储用户的联系人，并在打开ViewContacts页面（我在下面附带的java文件中）时显示它。 我想将检索到的值转换为字符串，以便每个值都可以作为参数传递给ArrayAdapter，以在ListView中显示值。

目前，我正在使用此代码段来执行此任务，但是，我的应用程序正在崩溃此声明。

if(c.moveToFirst())
        {
            do{
                str.add(c.getString(0));
            }while(c.moveToNext());
        }

请建议我执行此转换的正确方法。我的目的只是打印一列，即＆＃34; name＆＃34;来自页面上的数据库。

package app.shriram;

import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;

public class ViewContacts extends AppCompatActivity {
    ListView contactList;
    SQLiteDatabase db;
    ArrayList<String> str = new ArrayList<String>();
    String sql;

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

        contactList = (ListView)findViewById(R.id.contact_list_view);

        db = openOrCreateDatabase("db_addressBook", MODE_PRIVATE, null);

        SharedPreferences pref = getSharedPreferences("ShriRam", MODE_PRIVATE);
        String emailId = pref.getString("Email", "");

        db.execSQL("CREATE TABLE IF NOT EXISTS tbl_contacts (cname varchar(100)," +
                "cmobile varchar(20), cemail varchar(100), uemail varchar(100))");

        sql = "SELECT name FROM tbl_contacts WHERE uemail = '" + emailId + "'";
        Cursor c = db.rawQuery(sql, null);

        if(c.moveToFirst())
        {
            do{
                str.add(c.getString(0));
            }while(c.moveToNext());
        }

        ArrayAdapter<String> adpt = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item, str);
        contactList.setAdapter(adpt);
    }

    public void back_arrow_fn2(View view) {
        startActivity(new Intent(this, HomePage.class));
    }

    //need to have a delete option
    //need to dynamically created markers for contacts to delete them selectively.
}

XML文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".ViewContacts">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="1">

        <ImageView
            android:onClick="back_arrow_fn2"
            android:layout_width="52dp"
            android:layout_height="match_parent"
            android:src="@drawable/ic_arrow_back_black_24dp"
            android:layout_weight="0.02" />
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="MY ADDRESS BOOK"
            android:gravity="center"
            android:textSize="20dp"
            android:textStyle="italic"
            android:padding="15dp"
            android:layout_weight="0.96"/>
        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="0.02"
            android:src="@drawable/ic_exit_to_app_black_24dp"
            android:background="#EBF5FB"/>

    </LinearLayout>

    <ScrollView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ListView
            android:id="@+id/contact_list_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">

        </ListView>
    </LinearLayout>

    </ScrollView>
</LinearLayout>