Mega Code Archive
Create, delete, update
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package app.test;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
class DBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_NAME = "name";
public static final String KEY_EMAIL = "email";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "MyDB";
private static final String DATABASE_TABLE = "contacts";
private static final int DATABASE_VERSION = 2;
private static final String DATABASE_CREATE = "create table contacts (_id integer primary key autoincrement, "
+ "name text not null, email text not null);";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx) {
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
try {
db.execSQL(DATABASE_CREATE);
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, oldVersion + " to " + newVersion
+ ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS contacts");
onCreate(db);
}
}
public DBAdapter open() throws SQLException {
db = DBHelper.getWritableDatabase();
return this;
}
public void close() {
DBHelper.close();
}
public long insertContact(String name, String email) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_NAME, name);
initialValues.put(KEY_EMAIL, email);
return db.insert(DATABASE_TABLE, null, initialValues);
}
public boolean deleteContact(long rowId) {
return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
public Cursor getAllContacts() {
return db.query(DATABASE_TABLE, new String[] { KEY_ROWID, KEY_NAME,
KEY_EMAIL }, null, null, null, null, null);
}
public Cursor getContact(long rowId) throws SQLException {
Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {
KEY_ROWID, KEY_NAME, KEY_EMAIL }, KEY_ROWID + "=" + rowId,
null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public boolean updateContact(long rowId, String name, String email) {
ContentValues args = new ContentValues();
args.put(KEY_NAME, name);
args.put(KEY_EMAIL, email);
return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}
public class Test extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
String destPath = "/data/data/" + getPackageName()
+ "/databases/MyDB";
File f = new File(destPath);
if (!f.exists()) {
CopyDB(getBaseContext().getAssets().open("mydb"),
new FileOutputStream(destPath));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
DBAdapter db = new DBAdapter(this);
// ---add a contact---
db.open();
long id = db.insertContact("Wei-Meng Lee",
"weimenglee@learn2develop.net");
id = db.insertContact("Mary Jackson", "mary@jackson.com");
db.close();
// ---get all contacts---
db.open();
Cursor c = db.getAllContacts();
if (c.moveToFirst()) {
do {
DisplayContact(c);
} while (c.moveToNext());
}
db.close();
// ---get a contact---
db.open();
c = db.getContact(2);
if (c.moveToFirst())
DisplayContact(c);
else
Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show();
db.close();
// ---update contact---
db.open();
if (db.updateContact(1, "Wei-Meng Lee", "weimenglee@gmail.com"))
Toast.makeText(this, "Update successful.", Toast.LENGTH_LONG)
.show();
else
Toast.makeText(this, "Update failed.", Toast.LENGTH_LONG).show();
db.close();
// ---delete a contact---
db.open();
if (db.deleteContact(1))
Toast.makeText(this, "Delete successful.", Toast.LENGTH_LONG)
.show();
else
Toast.makeText(this, "Delete failed.", Toast.LENGTH_LONG).show();
db.close();
}
public void CopyDB(InputStream inputStream, OutputStream outputStream)
throws IOException {
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) > 0) {
outputStream.write(buffer, 0, length);
}
inputStream.close();
outputStream.close();
}
public void DisplayContact(Cursor c) {
Toast.makeText(
this,
"id: " + c.getString(0) + "\n" + "Name: " + c.getString(1)
+ "\n" + "Email: " + c.getString(2), Toast.LENGTH_LONG)
.show();
}
}
//main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
</LinearLayout>
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