错误应用程序意外停止

时间:2013-01-13 17:56:56

标签: android android-manifest

我在android 2.2中运行程序。我收到错误应用程序意外停止然后强制关闭。我一次又一次清理项目然后构建但问题仍然存在。

ApplicationContextProvider.java

package com.android.tuts;

import android.app.Application;
import android.content.Context;

public class ApplicationContextProvider  extends Application{
private static Context sContext;

 @Override
    public void onCreate() {
        super.onCreate();
        sContext = getApplicationContext();

    }

 public static Context getContext() {
        return sContext;
    }

}

DataBaseManage.java

package com.android.tuts;

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

import android.content.ContentValues;
 import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseManager extends SQLiteOpenHelper {
  // The Android's default system path of your application database.
//data/data/ and /databases remain the same always. The one that must be changed is com.example      which represents
//the MAIN package of your project
private static String DB_PATH = "/data/data/com.android/databases/";

//the name of your database
private static String DB_NAME = "database";

private static SQLiteDatabase mDataBase;

private static DataBaseManager sInstance = null;
// database version    
private static final int DATABASE_VERSION = 1;

/**
 * Constructor Takes and keeps a reference of the passed context in order to
 * access to the application assets and resources.
 */
private DataBaseManager() {
    super(ApplicationContextProvider.getContext(), DB_NAME, null, DATABASE_VERSION);

    try {
        createDataBase();
        openDataBase();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

/**
 * Singleton for DataBase
 *
 * @return singleton instance
 */
public static DataBaseManager instance() {

    if (sInstance == null) {
        sInstance = new DataBaseManager();
    }
    return sInstance;
}


/**
 * Creates a empty database on the system and rewrites it with your own
 * database.
 *
 * @throws java.io.IOException io exception
 */
private void createDataBase() throws IOException {

    boolean dbExist = checkDataBase();

    if (dbExist) {
        // do nothing - database already exist
    } else {

        // By calling this method an empty database will be created into
        // the default system path
        // of your application so we are gonna be able to overwrite that
        // database with our database.
        this.getReadableDatabase();

        try {

            copyDataBase();

        } catch (IOException e) {

            throw new Error("Error copying database");
        }
    }
}

/**
 * Check if the database already exist to avoid re-copying the file each
 * time you open the application.
 *
 * @return true if it exists, false if it doesn't
 */
private boolean checkDataBase() {

    SQLiteDatabase checkDB = null;

    try {
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null,
                SQLiteDatabase.OPEN_READONLY);

    } catch (SQLiteException e) {

        // database doesn't exist yet.

    }

    if (checkDB != null) {

        checkDB.close();

    }

    return checkDB != null;
}

/**
 * Copies your database from your local assets-folder to the just created
 * empty database in the system folder, from where it can be accessed and
 * handled. This is done by transfering bytestream.
 *
 * @throws java.io.IOException io exception
 */
public void copyDataBase() throws IOException {

    // Open your local db as the input stream
    InputStream myInput = ApplicationContextProvider.getContext().getAssets().open(DB_NAME);

    // Path to the just created empty db
    String outFileName = DB_PATH + DB_NAME;

    // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);

    // transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }

    // Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();

}

private void openDataBase() throws SQLException {

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

/**
 * Select method
 *
 * @param query select query
 * @return - Cursor with the results
 * @throws android.database.SQLException sql exception
 */
public Cursor select(String query) throws SQLException {
    return mDataBase.rawQuery(query, null);
}

/**
 * Insert method
 *
 * @param table  - name of the table
 * @param values values to insert
 * @throws android.database.SQLException sql exception
 */
public void insert(String table, ContentValues values) throws SQLException {
    mDataBase.insert(table, null, values);
}

/**
 * Delete method
 *
 * @param table - table name
 * @param where WHERE clause, if pass null, all the rows will be deleted
 * @throws android.database.SQLException sql exception
 */
public void delete(String table, String where) throws SQLException {

    mDataBase.delete(table, where, null);

}

/**
 * Update method
 *
 * @param table  - table name
 * @param values - values to update
 * @param where  - WHERE clause, if pass null, all rows will be updated
 */
public void update(String table, ContentValues values, String where) {

    mDataBase.update(table, values, where, null);

}

/**
 * Let you make a raw query
 *
 * @param command - the sql comand you want to run
 */
public void sqlCommand(String command) {
    mDataBase.execSQL(command);
}

@Override
public synchronized void close() {

    if (mDataBase != null)
        mDataBase.close();

    super.close();

}

@Override
public void onCreate(SQLiteDatabase db) {

}

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

}

}

MyActivity.java

package com.android.tuts;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MyActivity extends Activity {

private DataBaseManager dataBase;

private Button insertButton;
private Button updateButton;
private Button deleteButton;

private TextView textView;

//put the table name and column in constants
public static final String TABLE_NAME = "People";
public static final String COLUMN_NAME = "name";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    dataBase = DataBaseManager.instance();

    textView = (TextView)findViewById(R.id.name_1);
    insertButton = (Button)findViewById(R.id.insert);
    updateButton = (Button)findViewById(R.id.update);
    deleteButton = (Button)findViewById(R.id.delete);

    insertButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            //with ContentValues put the data we want into the database
            ContentValues values = new ContentValues();
            values.put(COLUMN_NAME, "Diana");

            //here we insert the data we have put in values
            dataBase.insert(TABLE_NAME, values);

            updateTextView();

        }
    });

    updateButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            //with ContentValues put the data we want into the database
            ContentValues values = new ContentValues();
            values.put(COLUMN_NAME,"George");

            //here we replace the record which has the _id=1 with the given name in the values "George"
            dataBase.update(TABLE_NAME, values, "_id=1");

            updateTextView();
        }
    });

    deleteButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            //here we delete the record which has the "name=George"
            dataBase.delete(TABLE_NAME,"name='George'");

            updateTextView();


        }
    });

}

@SuppressWarnings("null")
public void updateTextView(){
    //to get data from database we need a cursor.
    //after we perform a select query all the data from database specific for the query, will be in the cursor
    // "*" means "all" in translation the query means "SELECT ALL FROM NAME TABLE"
    Cursor cursor = dataBase.select("SELECT * FROM " + TABLE_NAME);

    //here we verify the cursor for null. If is null then the cursor must be closed.
    //Once you open a cursor you have to close it too after you don't use it
    if (cursor == null){
        cursor.close();
    }

    textView.setText("");
    //the cursor iterates the column "name"
    while (cursor.moveToNext()){
        //in this string we get the record for each row from the column "name"

        String s = cursor.getString(cursor.getColumnIndex(COLUMN_NAME));

        //in this textView will be added, updated or deleted the string
        // "\n" means "new line"
        textView.append("\n" + s);
    }

    //here we close the cursor because we do not longer need it
    cursor.close();
}
}

清单

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

<application android:name=".ApplicationContextProvider" android:label="@string/app_name">
<activity android:name=".MyActivity"
          android:label="@string/app_name">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

</application>
</manifest>

0 个答案:

没有答案