java.lang.runtimeexception:无法启动活动组件信息{}:java.lang.nullpointexception

我创建了一个类和活动，让用户填写一个表单并将其存储在数据库中，但我得到了空指针异常。我查阅了不少类似的帖子，但似乎没有一篇能解决我的问题。请让我知道我做错了什么

非常感谢您的时间和考虑

以下是我的活动：

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".Splash" 
><!--  android:background="@drawable/erc"-->

<EditText
    android:id="@+id/prayerRequestEditText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginLeft="30dp"
    android:layout_marginTop="10dp"
    android:ems="10"
    android:hint="@string/prayer_request"
    android:inputType="textMultiLine" >
    <requestFocus />
</EditText>

<EditText
    android:id="@+id/prayForEditText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/prayerRequestEditText"
    android:layout_below="@+id/prayerRequestEditText"
    android:layout_marginTop="30dp"
    android:ems="10"
    android:hint="@string/pray_for" />

<TextView
    android:id="@+id/confidentialTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/prayForEditText"
    android:layout_below="@+id/prayForEditText"
    android:layout_marginTop="30dp"
    android:text="@string/confidential"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<Switch
    android:id="@+id/confidentialSwitch"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/confidentialTextView"
    android:layout_alignRight="@+id/prayForEditText"
    android:textOff="@string/no"
    android:textOn="@string/yes" />

<TextView
    android:id="@+id/anonymousTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignRight="@+id/confidentialTextView"
    android:layout_below="@+id/confidentialTextView"
    android:layout_marginTop="30dp"
    android:text="@string/anonymous"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<Switch
    android:id="@+id/anonymousSwitch"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/anonymousTextView"
    android:layout_alignBottom="@+id/anonymousTextView"
    android:layout_alignRight="@+id/confidentialSwitch"
    android:textOff="@string/no"
    android:textOn="@string/yes" />

<Button
    android:id="@+id/sendRequestButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/anonymousTextView"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="30dp"
    android:onClick="sendRequest"
    android:text="@string/send_request" />

}

我有一个启动活动作为我的启动活动，在启动显示3秒钟后，祈祷请求表应该会弹出。 这是我的舱单：

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.eastridgetoday.prayerrequest"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="14"
    android:targetSdkVersion="17" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.eastridgetoday.prayerrequest.Splash"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name="com.eastridgetoday.prayerrequest.PrayerRequest"
        android:label="@string/app_name" >

    </activity>
</application>

这是我的日志：

    05-31 01:16:45.353: E/Trace(3070): error opening trace file: No such file or directory (2)
   05-31 01:16:52.834: E/AndroidRuntime(3070): FATAL EXCEPTION: main
   05-31 01:16:52.834: E/AndroidRuntime(3070): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.eastridgetoday.prayerrequest/com.eastridgetoday.prayerrequest.PrayerRequest}: java.lang.NullPointerException
   05-31 01:16:52.834: E/AndroidRuntime(3070):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
    05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
   05-31 01:16:52.834: E/AndroidRuntime(3070):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
    05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.os.Looper.loop(Looper.java:137)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.app.ActivityThread.main(ActivityThread.java:5041)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at java.lang.reflect.Method.invokeNative(Native Method)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at java.lang.reflect.Method.invoke(Method.java:511)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at dalvik.system.NativeStart.main(Native Method)
05-31 01:16:52.834: E/AndroidRuntime(3070): Caused by: java.lang.NullPointerException
05-31 01:16:52.834: E/AndroidRuntime(3070):     at com.eastridgetoday.prayerrequest.DbHelper.onCreate(DbHelper.java:35)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at com.eastridgetoday.prayerrequest.PrayerRequest.onCreate(PrayerRequest.java:20)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.app.Activity.performCreate(Activity.java:5104)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
05-31 01:16:52.834: E/AndroidRuntime(3070):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
05-31 01:16:52.834: E/AndroidRuntime(3070):     ... 11 more

下面是我的DbHelper类：

    package com.eastridgetoday.prayerrequest;
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;

    public class DbHelper extends SQLiteOpenHelper {

SQLiteDatabase db;

public static final String DATABASE_NAME = "prayersdb";
public static final String TABLE_NAME = "prayers_table";
public static final String P_ID = "_id";
public static final String PRAYER_REQUEST = "prayers";
public static final String PRAY_FOR = "pray_for";
public static final String CONFIDENTIAL = "confidential";
public static final String ANONYMOUS = "anonymous";
public static final int VERSION = 1;

public final String createTable = 
        "create table if not exists " + TABLE_NAME + " ( "
        + P_ID + " integer primary key autoincrement "
        + PRAYER_REQUEST + " text "
        + PRAY_FOR + " text "
        + CONFIDENTIAL +" text "
        + ANONYMOUS + " text);";

public DbHelper (Context context){
    super(context, DATABASE_NAME, null, VERSION);

}

@Override
public void onCreate(SQLiteDatabase arg0) {
    db.execSQL(createTable);

}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    db.execSQL("drop table " + TABLE_NAME);

}

@Override
public void onCreate(SQLiteDatabase arg0) {
    db.execSQL(createTable);
}

---

}问题出在DbHelper类中：

    package com.eastridgetoday.prayerrequest;
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;

    public class DbHelper extends SQLiteOpenHelper {

SQLiteDatabase db;

public static final String DATABASE_NAME = "prayersdb";
public static final String TABLE_NAME = "prayers_table";
public static final String P_ID = "_id";
public static final String PRAYER_REQUEST = "prayers";
public static final String PRAY_FOR = "pray_for";
public static final String CONFIDENTIAL = "confidential";
public static final String ANONYMOUS = "anonymous";
public static final int VERSION = 1;

public final String createTable = 
        "create table if not exists " + TABLE_NAME + " ( "
        + P_ID + " integer primary key autoincrement "
        + PRAYER_REQUEST + " text "
        + PRAY_FOR + " text "
        + CONFIDENTIAL +" text "
        + ANONYMOUS + " text);";

public DbHelper (Context context){
    super(context, DATABASE_NAME, null, VERSION);

}

@Override
public void onCreate(SQLiteDatabase arg0) {
    db.execSQL(createTable);

}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    db.execSQL("drop table " + TABLE_NAME);

}

@Override
public void onCreate(SQLiteDatabase arg0) {
    db.execSQL(createTable);
}

---

db

为空，您必须初始化它。

我认为您没有正确使用DBHelper。您应该有一个扩展dbhelper的类。看一看教程。您没有正确连接到您的计算机db@TanjaV谢谢你的意见。你能详细解释一下我没有正确使用它的确切含义吗。我已经在上面添加了我的DbHelper类。谢谢谢谢你@Torben Kohlmeier。这绝对是错误之一。