0

更新 4

これは私の DBhelper クラスです

      package com.example.dbtest;

       import java.io.File;
     import java.io.FileOutputStream;
    import java.io.IOException;
      import java.io.InputStream;
       import java.io.OutputStream;

        import android.content.Context;
        import android.database.Cursor;
       import android.database.SQLException;
      import android.database.sqlite.SQLiteDatabase;
       import android.database.sqlite.SQLiteOpenHelper;

       public class DBhelper extends SQLiteOpenHelper {

String tablename;

Cursor ch;

private static String DB_PATH = "/data/data/com.example.dbtest/databases/";
public static String DB_NAME = "photodb";
private SQLiteDatabase myDataBase;
private  Context myContext;



public DBhelper(Context cont) {
    super(cont, DB_NAME, null, 3);

}


public void createDataBase() throws IOException {

    boolean dbExist = checkDataBase();
    if (!dbExist) {
        boolean flag = isOpen();
        if(flag==false){
        //this.getWritableDatabase();
        this.getReadableDatabase();

            //myDataBase = SQLiteDatabase.openDatabase(DB_PATH,null, SQLiteDatabase.OPEN_READWRITE|SQLiteDatabase.NO_LOCALIZED_COLLATORS);


        try {

            copyDataBase();

        } catch (IOException e) {
            throw new Error("Error copying database");
        }
    }
    }

}



public boolean checkDataBase()
{
    File dbFile = new File(DB_PATH + DB_NAME);
    return dbFile.exists();
}



private void copyDataBase() throws IOException  {


    InputStream myInput;

        myInput = myContext.getAssets().open("photodb");


    String outFileName = DB_PATH + DB_NAME;


    OutputStream myOutput;

        myOutput = new FileOutputStream(outFileName);



    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }


    myOutput.flush();
    myOutput.close();
    myInput.close();


}

public boolean isOpen() {
    if (myDataBase != null)
        return myDataBase.isOpen();
    return false;
}


public void openDataBase() throws SQLException {

    // Open the database
    String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null,
            SQLiteDatabase.OPEN_READWRITE);

}

@Override
public synchronized void close() {
    if (myDataBase != null)
        myDataBase.close();
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}



public void add_pics(String imagepath,String description,String location)

{


    myDataBase.execSQL("insert into photodetails values(null," + imagepath + ","
            + description + "," + location + ");");

}

}

そして、これは私の MainActivity です

       package com.example.dbtest;



     import java.io.IOException;

      import android.os.Bundle;
      import android.app.Activity;
     import android.content.Context;
       import android.view.Menu;

 public class MainActivity extends Activity {


DBhelper mydb;
Context cont;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mydb = new DBhelper(cont);

    try {
        mydb.createDataBase();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    mydb.openDataBase();
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

そして私のlogcatエラーは

09-02 18:43:26.052: E/AndroidRuntime(25477): 致命的な例外: メイン 09-02 18:43:26.052: E/AndroidRuntime(25477): java.lang.RuntimeException: アクティビティ ComponentInfo{com を開始できません。 example.dbtest/com.example.dbtest.MainActivity}: java.lang.NullPointerException 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110) で 09 -02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app で.ActivityThread.access$700(ActivityThread.java:140) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237) 09-02 18: 43:26.052: E/AndroidRuntime(25477): android.os.Handler.dispatchMessage(Handler.java:99) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.os.Looper.loop(Looper.java:137) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.main で(ActivityThread.java:4921) 09-02 18:43:26.052: E/AndroidRuntime(25477): java.lang.reflect.Method.invokeNative(ネイティブ メソッド) 09-02 18:43:26.052: E/AndroidRuntime( 25477): java.lang.reflect.Method.invoke(Method.java:511) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run で(ZygoteInit.java:1027) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794) 09-02 18:43:26.052 : E/AndroidRuntime(25477): dalvik.system.NativeStart.main(Native Method) 09-02 18:43:26.052: E/AndroidRuntime(25477): 原因: java.lang.NullPointerException 09-02 18:43 :26.052:E/AndroidRuntime(25477): android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.database.sqlite.SQLiteOpenHelper.getReadableDatabase で(SQLiteOpenHelper.java:188) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E /AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity. java:5206) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18:43:26.052: E/AndroidRuntime(25477) : android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) でandroid.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) で09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): at com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity.java:5206) で 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread で.performLaunchActivity(ActivityThread.java:2074)android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) で09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): at com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity.java:5206) で 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread で.performLaunchActivity(ActivityThread.java:2074)getDatabaseLocked(SQLiteOpenHelper.java:224) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate で(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity.java:5206) 09-02 18:43:26.052: E/AndroidRuntime (25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) でgetDatabaseLocked(SQLiteOpenHelper.java:224) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate で(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity.java:5206) 09-02 18:43:26.052: E/AndroidRuntime (25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) でandroid.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): at android.app.Activity.performCreate(Activity.java:5206) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18: 43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) でandroid.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.DBhelper.createDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): at android.app.Activity.performCreate(Activity.java:5206) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094) 09-02 18: 43:26.052: E/AndroidRuntime(25477): android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074) でcreateDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity.java:5206) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java) :1094) 09-02 18:43:26.052: E/AndroidRuntime (25477): android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2074) でcreateDataBase(DBhelper.java:41) 09-02 18:43:26.052: E/AndroidRuntime(25477): com.example.dbtest.MainActivity.onCreate(MainActivity.java:25) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Activity.performCreate(Activity.java:5206) 09-02 18:43:26.052: E/AndroidRuntime(25477): android.app.Instrumentation.callActivityOnCreate(Instrumentation.java) :1094) 09-02 18:43:26.052: E/AndroidRuntime (25477): android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2074) でjava:1094) 09-02 18:43:26.052: E/AndroidRuntime (25477): android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2074) でjava:1094) 09-02 18:43:26.052: E/AndroidRuntime (25477): android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2074) で

4

2 に答える 2

0

あなたが試すことができます

public boolean checkDataBase()
{
    File dbFile = new File(DB_PATH + DB_NAME);
    return dbFile.exists();
}

それ以外の

private boolean checkDataBase() {
        SQLiteDatabase checkDB = null;
        try {
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null,
                    SQLiteDatabase.OPEN_READWRITE);
        } catch (SQLiteException e) {
            // database does't exist yet.
        }
        if (checkDB != null) {
            checkDB.close();
        }

        return checkDB != null ? true : false;
    }

アップデート：

次の例外が発生していますandroid.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224)

の複数のインスタンスを開こうとしているためですSQLiteDatabase。一度に 1 つのインスタンスのみが開いていることを確認してください。パターンDBhelperを使用して実装できます。Singeltonそのために、これを参照できます

于 2013-09-02T10:52:53.793 に答える