本文介绍了构造函数SQLiteOpenHelper（）是未定义的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
所以，当我启动应用程序我得到的致命异常主要说没有空的构造。
然后，当我加空构造它给我说：构造SQLiteOpenHelper（）是未定义的错误。
这是我的第一个应用程序不断，所以我不知道该怎么做。
这里的code：
包com.example.lightalarmclock;进口android.app.Activity;
进口android.content.Context;
进口android.content.Intent;
进口android.content.Shared preferences;
进口android.database.sqlite.SQLiteDatabase;
进口android.database.sqlite.SQLiteDatabase.CursorFactory;
进口android.database.sqlite.SQLiteOpenHelper;
进口android.os.Bundle;公共类writeAlarm延伸活动{ 公共静态最后弦乐preFS =阵地;
私人最终上下文ourContext;
私人SQLiteDatabase ourDatabase;
私人DbHelper ourHelper; 私人静态字符串POS1 =0;
私人静态字符串POS2 =0;
私人静态字符串POS3 =0;
私人静态字符串POS4 =0;
私人静态字符串timeSet; 私有静态诠释REP1 = 0;
私有静态诠释REP2 = 0;
私有静态诠释rep3 = 0;
私有静态诠释rep4 = 0;
私有静态诠释rep5 = 0;
私有静态诠释rep6 = 0;
私有静态诠释rep7 = 0;
私有静态诠释repB;
私有静态诠释repSet; 私有静态最后弦乐DATABASE_NAME =alarmDB;
私有静态最后弦乐DATABASE_TABLE =alarmStack;
私有静态最终诠释DATABASE_VERSION = 1; @覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
} 公共无效updateVars（）{
共享preferences位置= getShared preferences（preFS，0）;
//从共享preferences到本地变量TODO进口
} 私有静态类DbHelper扩展SQLiteOpenHelper {
公共DbHelper（上下文的背景下）{
超（背景下，DATABASE_NAME，空，DATABASE_VERSION）;
} 公共DbHelper（）{
超（）;
} @覆盖
公共无效的onCreate（SQLiteDatabase DB）{
//写入数据库
如果（REP1＆GT; = 0 || REP2＆GT; = 0 || rep3＆GT; = 0 || rep4＆GT; = 0 || rep5＆GT; = 0 || rep6＆GT; = 0 || rep7＆GT; = 0） {
repB = 1;
}
其他{
repB = 0;
} //设置时间
timeSet = POS4 + POS3 +：+ POS2 + POS1; //写作
db.execSQL
（INSERT INTO TABLE alarmDB.alarmStack（ALARM_TIME，alarm_repeat，REP1，REP2，rep3，rep4，rep5，rep6，rep7）+
VALUES（+ timeSet +，+ repB +，+ REP1 +，+ REP2 +，+ rep3 +，+ rep4 +，+ rep5 +，+ rep6 + ，+ rep7 +））; //推出backToMain
backToMain（NULL）;
} 公共静态无效backToMain（上下文CTX）{
//做一些东西在这里
ctx.startActivity（新意图（CTX，MainActivity.class））;
} @覆盖
公共无效onUpgrade（SQLiteDatabase分贝，INT oldVersion，诠释静态网页）{
db.execSQL（DROP TABLE IF EXISTS+ DATABASE_TABLE）;
的onCreate（DB）;
}
} 公共无效backToMain（）{
意向J =新意图（writeAlarm.this，MainActivity.class）;
startActivity（J）;
} 公共writeAlarm（上下文C）{
ourContext = C;
} 公共writeAlarm的open（）{
ourHelper =新DbHelper（ourContext）;
ourDatabase = ourHelper.getWritableDatabase（）;
返回此;
} 公共无效的close（）{
ourHelper.close（）;
}
}
解决方案
对于类 DbHelper扩展SQLiteOpenHelper 你这样做是：
公共DbHelper（）{
超（）;
}
如果您在 Android的文档，没有 SQLiteOpenHelper（）的构造，因此在抱怨。
So when I launch the app I get the fatal exception main saying that there is no empty constructor.Then when I add the empty constructor it gives me that "The constructor SQLiteOpenHelper() is undefined" error.
This is my first app ever so I have no clue what to do.
Here's the code:
package com.example.lightalarmclock;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
public class writeAlarm extends Activity {
public static final String PREFS = "positions";
private final Context ourContext;
private SQLiteDatabase ourDatabase;
private DbHelper ourHelper;
private static String pos1 = "0";
private static String pos2 = "0";
private static String pos3 = "0";
private static String pos4 = "0";
private static String timeSet;
private static int rep1 = 0;
private static int rep2 = 0;
private static int rep3 = 0;
private static int rep4 = 0;
private static int rep5 = 0;
private static int rep6 = 0;
private static int rep7 = 0;
private static int repB;
private static int repSet;
private static final String DATABASE_NAME = "alarmDB";
private static final String DATABASE_TABLE = "alarmStack";
private static final int DATABASE_VERSION = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public void updateVars() {
SharedPreferences positions = getSharedPreferences(PREFS, 0);
//TODO import from sharedPreferences to local vars
}
private static class DbHelper extends SQLiteOpenHelper {
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public DbHelper() {
super();
}
@Override
public void onCreate(SQLiteDatabase db) {
//writing to database
if (rep1 >= 0 || rep2 >= 0 || rep3 >= 0 || rep4 >= 0 || rep5 >= 0 || rep6 >= 0 || rep7 >= 0) {
repB = 1;
}
else {
repB = 0;
}
//setting time
timeSet= pos4+pos3+":"+pos2+pos1;
//Writing
db.execSQL
("INSERT INTO TABLE alarmDB.alarmStack(alarm_time, alarm_repeat, rep1, rep2, rep3, rep4, rep5, rep6, rep7) " +
"VALUES (" + timeSet + ", " + repB + ", "+ rep1 +", "+ rep2 +", "+ rep3 +", "+ rep4 +", "+ rep5 +", "+ rep6 +", "+ rep7 +")");
//launch backToMain
backToMain(null);
}
public static void backToMain(Context ctx) {
// do some stuff here
ctx.startActivity(new Intent(ctx, MainActivity.class));
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
onCreate(db);
}
}
public void backToMain() {
Intent j = new Intent(writeAlarm.this, MainActivity.class);
startActivity(j);
}
public writeAlarm (Context c) {
ourContext = c;
}
public writeAlarm open() {
ourHelper = new DbHelper(ourContext);
ourDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close() {
ourHelper.close();
}
}
解决方案
For class DbHelper extends SQLiteOpenHelper you are doing this:
public DbHelper() {
super();
}
If you look in the Android docs for SQLiteOpenHelper, there is no SQLiteOpenHelper() constructor so it is complaining.
这篇关于构造函数SQLiteOpenHelper（）是未定义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！