写一个人日记本程序，有日历，在安卓手机上运行

以下是一个简单的人日记本程序的代码示例，可以在安卓手机上运行：

1. MainActivity.java

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.DialogFragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CalendarView;
import android.widget.EditText;
import android.widget.Toast;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

public class MainActivity extends AppCompatActivity implements DatePickerFragment.OnDateSetListener {

    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;
    private RecyclerView.LayoutManager layoutManager;

    private List<Diary> diaryList;

    private Button dateButton;
    private EditText contentEditText;

    private String currentDate;

    private DatabaseHelper databaseHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);

        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);

        diaryList = new ArrayList<>();
        adapter = new DiaryAdapter(diaryList);
        recyclerView.setAdapter(adapter);

        dateButton = findViewById(R.id.date_button);
        contentEditText = findViewById(R.id.content_edit_text);

        Calendar calendar = Calendar.getInstance();
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        currentDate = dateFormat.format(calendar.getTime());
        dateButton.setText(currentDate);

        databaseHelper = new DatabaseHelper(this);

        updateDiaryList();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        if (item.getItemId() == R.id.action_add) {
            showDatePickerDialog();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    public void onSaveButtonClick(View view) {
        String content = contentEditText.getText().toString().trim();
        if (content.isEmpty()) {
            Toast.makeText(this, "请填写日记内容", Toast.LENGTH_SHORT).show();
            return;
        }
        Diary diary = new Diary(currentDate, content);
        databaseHelper.addDiary(diary);
        updateDiaryList();
        contentEditText.setText("");
    }

    private void updateDiaryList() {
        diaryList.clear();
        diaryList.addAll(databaseHelper.getDiaryList(currentDate));
        adapter.notifyDataSetChanged();
    }

    private void showDatePickerDialog() {
        DialogFragment newFragment = new DatePickerFragment();
        newFragment.show(getSupportFragmentManager(), "datePicker");
    }

    @Override
    public void onDateSet(int year, int month, int day) {
        currentDate = String.format("%04d-%02d-%02d", year, month + 1, day);
        dateButton.setText(currentDate);
        updateDiaryList();
    }
}

2. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/input_layout"
        android:padding="16dp" />

    <LinearLayout
        android:id="@+id/input_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="vertical"
        android:padding="16dp">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <Button
                android:id="@+id/date_button"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="日期" />

            <Button
                android:id="@+id/save_button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="保存"
                android:onClick="onSaveButtonClick" />

        </LinearLayout>

        <EditText
            android:id="@+id/content_edit_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="日记内容" />

    </LinearLayout>

</RelativeLayout>

3. Diary.java

public class Diary {

    private String date;
    private String content;

    public Diary(String date, String content) {
        this.date = date;
        this.content = content;
    }

    public String getDate() {
        return date;
    }

    public String getContent() {
        return content;
    }
}

4. DiaryAdapter.java

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class DiaryAdapter extends RecyclerView.Adapter<DiaryAdapter.DiaryViewHolder> {

    private List<Diary> diaryList;

    public DiaryAdapter(List<Diary> diaryList) {
        this.diaryList = diaryList;
    }

    @NonNull
    @Override
    public DiaryViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.diary_item, parent, false);
        return new DiaryViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull DiaryViewHolder holder, int position) {
        Diary diary = diaryList.get(position);
        holder.dateTextView.setText(diary.getDate());
        holder.contentTextView.setText(diary.getContent());
    }

    @Override
    public int getItemCount() {
        return diaryList.size();
    }

    public static class DiaryViewHolder extends RecyclerView.ViewHolder {

        public TextView dateTextView;
        public TextView contentTextView;

        public DiaryViewHolder(@NonNull View itemView) {
            super(itemView);
            dateTextView = itemView.findViewById(R.id.date_text_view);
            contentTextView = itemView.findViewById(R.id.content_text_view);
        }
    }
}

5. diary_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@+id/date_text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:textAppearanceMedium"
        android:textColor="?android:attr/textColorPrimary" />

    <TextView
        android:id="@+id/content_text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:textAppearanceMedium"
        android:textColor="?android:attr/textColorSecondary" />

</LinearLayout>

6. DatePickerFragment.java

import android.app.DatePickerDialog;
import android.app.Dialog;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.DialogFragment;

import java.util.Calendar;

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {

    private OnDateSetListener listener;

    public interface OnDateSetListener {
        void onDateSet(int year, int month, int day);
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        try {
            listener = (OnDateSetListener) getActivity();
        } catch (ClassCastException e) {
            throw new ClassCastException(getActivity().toString() + " must implement OnDateSetListener");
        }
    }

    @NonNull
    @Override
    public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
        Calendar calendar = Calendar.getInstance();
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);
        return new DatePickerDialog(getActivity(), this, year, month, day);
    }

    @Override
    public void onDateSet(android.widget.DatePicker view, int year, int month, int dayOfMonth) {
        listener.onDateSet(year, month, dayOfMonth);
    }
}

这个程序包含一个日记列表和一个日历视图，可以添加新的日记并查看指定日期的日记列表。日记数据存储在SQLite数据库中。在添加新日记时，用户可以选择日期，也可以使用当前日期。