質問編集履歴
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@@ -1,7 +1,72 @@
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java.lang.NullPointerExceptionが SQLiteDatabase db=memoDBHelper.getWritableDatabase();に出るのですが、なぜなのでしょうか？
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アドバイスをいただけないでしょうか？
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どうぞよろしくお願いします。
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MemoDBHelper
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```java
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package com.example.android.sample.memo;
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7
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8
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import android.content.Context;
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import android.database.sqlite.SQLiteDatabase;
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import android.database.sqlite.SQLiteOpenHelper;
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/**
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* Created by endoutaichi on 2017/04/06.
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*/
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public class MemoDBHelper extends SQLiteOpenHelper {
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public static final String DB_NAME="myapp.db";
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public static final int DB_VERSION=1;
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public static final String CREATE_TABLE=
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"create table " + UserContract.Users.TABLE_NAME + "(" +
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UserContract.Users._ID+ " integer primary key autoincrement, " +
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UserContract.Users.COL_TITLE + " title," +
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UserContract.Users.COL_CONTENT + " content, +" +
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UserContract.Users.COL_DATA + "data" +
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")";
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/**"create table"+ UserContract.Users.TABLE_NAME+"("+
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UserContract.Users._ID+"integer primary key autoincrement,"+
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UserContract.Users.COL_NAME+"text,"+
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UserContract.Users.COL_SCORE+"integer)";
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**/
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public static final String INIT_TABLE=
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"insert into users (title,content,data)values" +
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"('仕事','出張','5月3日'),"+
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"('遊び','海','8月4日'),"+
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"('買い物','ららぽーと','3月3日')";
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public static final String DROP_TABLE=
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"drop table if exists users";
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public MemoDBHelper(Context c){
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super(c,DB_NAME,null,DB_VERSION);
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}
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@Override
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public void onCreate(SQLiteDatabase sqLiteDatabase) {
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//create table
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sqLiteDatabase.execSQL(CREATE_TABLE);
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//init table
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sqLiteDatabase.execSQL(INIT_TABLE);
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}
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@Override
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public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
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//drop table
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sqLiteDatabase.execSQL(DROP_TABLE);
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//onCreate
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onCreate(sqLiteDatabase);
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}
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}
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```
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MainActivity.java
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```java
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public class MainActivity extends AppCompatActivity {
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@@ -143,33 +208,4 @@
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at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2095)
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at android.app.ActivityThread.access$600(ActivityThread.java:137)
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at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1206)
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at android.os.Handler.dispatchMessage(Handler.java:99)
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at android.os.Looper.loop(Looper.java:213)
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at android.app.ActivityThread.main(ActivityThread.java:4786)
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149
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at java.lang.reflect.Method.invokeNative(Native Method)
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at java.lang.reflect.Method.invoke(Method.java:511)
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at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
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at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
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at dalvik.system.NativeStart.main(Native Method)
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Caused by: java.lang.NullPointerException
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at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:221)
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at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224)
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at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
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at com.example.android.sample.memo.MainActivity.<init>(MainActivity.java:51)
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at java.lang.Class.newInstanceImpl(Native Method)
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at java.lang.Class.newInstance(Class.java:1319)
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at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
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at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1985)
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at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2095)
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164
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at android.app.ActivityThread.access$600(ActivityThread.java:137)
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165
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at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1206)
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at android.os.Handler.dispatchMessage(Handler.java:99)
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167
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at android.os.Looper.loop(Looper.java:213)
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168
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at android.app.ActivityThread.main(ActivityThread.java:4786)
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169
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at java.lang.reflect.Method.invokeNative(Native Method)
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170
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at java.lang.reflect.Method.invoke(Method.java:511)
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at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
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at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
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173
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at dalvik.system.NativeStart.main(Native Method)
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174
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```
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