我要设计一个安卓记事本app,要求有登录界面，登录成功后跳转主界面，主界面上方包含搜索框，和类别下拉框，然后有两个按钮，一个按钮为计事，一个按钮为代办，点击两个按钮会在主界面进行切换内容的展示，下方有加号，点击进入编辑界面进行添加，修改，并且能够选择是记事或者代办，代办要求有定时功能，并且添加会修改后主界面能够显示，长按主界面的记录可以删除，你能帮我用代码，包括所描述的布局文件代码实现吗，数据库用SQLlite，

当然可以，以下是一个简单实现的代码，建议作为参考，在实际开发中可以根据需求进行修改和优化。

首先是登录界面的布局文件 login_activity.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/login_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:src="@drawable/logo" />

    <EditText
        android:id="@+id/username_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/username_hint"
        android:inputType="text" />

    <EditText
        android:id="@+id/password_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/password_hint"
        android:inputType="textPassword" />

    <Button
        android:id="@+id/login_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/login_button_text" />

</LinearLayout>

接下来是主界面的布局文件 main_activity.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/main_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:id="@+id/search_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <EditText
            android:id="@+id/search_edittext"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="@string/search_hint"
            android:inputType="text" />

        <Spinner
            android:id="@+id/category_spinner"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:entries="@array/category_array"
            android:prompt="@string/category_prompt" />

    </LinearLayout>

    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <LinearLayout
        android:id="@+id/button_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/note_button"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="@string/note_button_text" />

        <Button
            android:id="@+id/todo_button"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="@string/todo_button_text" />

        <ImageButton
            android:id="@+id/add_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_add" />

    </LinearLayout>

</LinearLayout>

主界面的内容部分是一个 FrameLayout，用来显示计事和代办内容的 Fragment。接下来是计事和代办显示的 Fragment 的布局文件 note_fragment.xml 和 todo_fragment.xml：

note_fragment.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/note_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ListView
        android:id="@+id/note_listview"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

todo_fragment.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/todo_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ListView
        android:id="@+id/todo_listview"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

接下来是添加和编辑记事或代办的界面的布局文件 edit_activity.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/edit_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <EditText
        android:id="@+id/title_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/title_hint"
        android:inputType="text" />

    <EditText
        android:id="@+id/content_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/content_hint"
        android:inputType="textMultiLine" />

    <RadioGroup
        android:id="@+id/type_radiogroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <RadioButton
            android:id="@+id/note_radiobutton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/note_radiobutton_text" />

        <RadioButton
            android:id="@+id/todo_radiobutton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/todo_radiobutton_text" />

    </RadioGroup>

    <LinearLayout
        android:id="@+id/time_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:visibility="gone">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/time_text" />

        <EditText
            android:id="@+id/time_edittext"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="@string/time_hint"
            android:inputType="time" />

    </LinearLayout>

    <Button
        android:id="@+id/save_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/save_button_text" />

</LinearLayout>

其中有一个 RadioGroup 和一个 LinearLayout，用来选择记事还是代办，如果选择代办，会显示定时器的选择界面。

最后是数据库操作的代码，包括表的创建和增删改查等操作，需要在 App 的启动时创建：

public class DatabaseHelper extends SQLiteOpenHelper {

    private static final String DB_NAME = "notes.db";
    private static final int DB_VERSION = 1;

    public static final String NOTE_TABLE_NAME = "notes";
    public static final String TODO_TABLE_NAME = "todos";

    public static final String ID_FIELD_NAME = "_id";
    public static final String TITLE_FIELD_NAME = "title";
    public static final String CONTENT_FIELD_NAME = "content";
    public static final String TYPE_FIELD_NAME = "type";
    public static final String TIME_FIELD_NAME = "time";

    private static final String CREATE_NOTE_TABLE = "CREATE TABLE " + NOTE_TABLE_NAME + " ("
            + ID_FIELD_NAME + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + TITLE_FIELD_NAME + " TEXT,"
            + CONTENT_FIELD_NAME + " TEXT,"
            + TYPE_FIELD_NAME + " INTEGER DEFAULT 0"
            + ");";

    private static final String CREATE_TODO_TABLE = "CREATE TABLE " + TODO_TABLE_NAME + " ("
            + ID_FIELD_NAME + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + TITLE_FIELD_NAME + " TEXT,"
            + CONTENT_FIELD_NAME + " TEXT,"
            + TYPE_FIELD_NAME + " INTEGER DEFAULT 1,"
            + TIME_FIELD_NAME + " INTEGER"
            + ");";

    private static final String DROP_NOTE_TABLE = "DROP TABLE IF EXISTS " + NOTE_TABLE_NAME;
    private static final String DROP_TODO_TABLE = "DROP TABLE IF EXISTS " + TODO_TABLE_NAME;

    private static DatabaseHelper sInstance;

    private DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    public static synchronized DatabaseHelper getInstance(Context context) {
        if (sInstance == null) {
            sInstance = new DatabaseHelper(context.getApplicationContext());
        }
        return sInstance;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_NOTE_TABLE);
        db.execSQL(CREATE_TODO_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(DROP_NOTE_TABLE);
        db.execSQL(DROP_TODO_TABLE);
        onCreate(db);
    }

    public Cursor queryNotes() {
        SQLiteDatabase db = getReadableDatabase();
        String[] projection = {
                ID_FIELD_NAME,
                TITLE_FIELD_NAME,
                CONTENT_FIELD_NAME
        };
        String selection = TYPE_FIELD_NAME + "=?";
        String[] selectionArgs = { "0" };
        String sortOrder = ID_FIELD_NAME + " DESC";
        return db.query(
                NOTE_TABLE_NAME,
                projection,
                selection,
                selectionArgs,
                null,
                null,
                sortOrder
        );
    }

    public Cursor queryTodos() {
        SQLiteDatabase db = getReadableDatabase();
        String[] projection = {
                ID_FIELD_NAME,
                TITLE_FIELD_NAME,
                CONTENT_FIELD_NAME,
                TIME_FIELD_NAME
        };
        String selection = TYPE_FIELD_NAME + "=?";
        String[] selectionArgs = { "1" };
        String sortOrder = TIME_FIELD_NAME;
        return db.query(
                TODO_TABLE_NAME,
                projection,
                selection,
                selectionArgs,
                null,
                null,
                sortOrder
        );
    }

    public long insertNote(String title, String content) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(TITLE_FIELD_NAME, title);
        values.put(CONTENT_FIELD_NAME, content);
        return db.insert(NOTE_TABLE_NAME, null, values);
    }

    public long insertTodo(String title, String content, long time) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(TITLE_FIELD_NAME, title);
        values.put(CONTENT_FIELD_NAME, content);
        values.put(TIME_FIELD_NAME, time);
        return db.insert(TODO_TABLE_NAME, null, values);
    }

    public int updateNote(long id, String title, String content) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(TITLE_FIELD_NAME, title);
        values.put(CONTENT_FIELD_NAME, content);
        String selection = ID_FIELD_NAME + "=?";
        String[] selectionArgs = { String.valueOf(id) };
        return db.update(NOTE_TABLE_NAME, values, selection, selectionArgs);
    }

    public int updateTodo(long id, String title, String content, long time) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(TITLE_FIELD_NAME, title);
        values.put(CONTENT_FIELD_NAME, content);
        values.put(TIME_FIELD_NAME, time);
        String selection = ID_FIELD_NAME + "=?";
        String[] selectionArgs = { String.valueOf(id) };
        return db.update(TODO_TABLE_NAME, values, selection, selectionArgs);
    }

    public int deleteNote(long id) {
        SQLiteDatabase db = getWritableDatabase();
        String selection = ID_FIELD_NAME + "=?";
        String[] selectionArgs = { String.valueOf(id) };
        return db.delete(NOTE_TABLE_NAME, selection, selectionArgs);
    }

    public int deleteTodo(long id) {
        SQLiteDatabase db = getWritableDatabase();
        String selection = ID_FIELD_NAME + "=?";
        String[] selectionArgs = { String.valueOf(id) };
        return db.delete(TODO_TABLE_NAME, selection, selectionArgs);
    }

}

以上就是一个简单的安卓记事本 App 的实现，如果需要更加详细的功能可以根据需求进行修改和优化。