用安卓写一个课表，可以添加课表、查看课表、修改课表，数据库用Sqlite，编程语言用java，带有注释

好的，下面是一个简单的安卓课表应用，包含添加课表、查看课表和修改课表功能，并使用 SQLite 数据库进行数据存储。注释已经添加在代码中，方便理解。

// MainActivity.java

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText mCourseNameEditText; // 课程名称编辑框
    private EditText mTeacherNameEditText; // 教师名称编辑框
    private EditText mClassroomEditText; // 教室编辑框
    private EditText mWeekdayEditText; // 星期编辑框
    private EditText mTimeEditText; // 时间编辑框
    private TextView mScheduleTextView; // 课表文本显示框

    private SQLiteDatabase mDatabase; // 数据库对象

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

        // 初始化 UI 组件
        mCourseNameEditText = findViewById(R.id.course_name_edit_text);
        mTeacherNameEditText = findViewById(R.id.teacher_name_edit_text);
        mClassroomEditText = findViewById(R.id.classroom_edit_text);
        mWeekdayEditText = findViewById(R.id.weekday_edit_text);
        mTimeEditText = findViewById(R.id.time_edit_text);
        mScheduleTextView = findViewById(R.id.schedule_text_view);
        Button addButton = findViewById(R.id.add_button);
        Button viewButton = findViewById(R.id.view_button);
        Button updateButton = findViewById(R.id.update_button);

        // 创建或打开数据库
        mDatabase = openOrCreateDatabase("schedule.db", MODE_PRIVATE, null);

        // 创建课表表格
        String createTableSql = "CREATE TABLE IF NOT EXISTS schedule (" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT," +
                "course_name TEXT," +
                "teacher_name TEXT," +
                "classroom TEXT," +
                "weekday INTEGER," +
                "time TEXT)";
        mDatabase.execSQL(createTableSql);

        // 添加按钮点击事件监听器
        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String courseName = mCourseNameEditText.getText().toString();
                String teacherName = mTeacherNameEditText.getText().toString();
                String classroom = mClassroomEditText.getText().toString();
                String weekdayString = mWeekdayEditText.getText().toString();
                String time = mTimeEditText.getText().toString();

                // 检查输入是否为空
                if (TextUtils.isEmpty(courseName) || TextUtils.isEmpty(weekdayString) || TextUtils.isEmpty(time)) {
                    Toast.makeText(MainActivity.this, "请填写完整信息", Toast.LENGTH_SHORT).show();
                    return;
                }

                // 解析星期
                int weekday = Integer.parseInt(weekdayString);

                // 插入数据
                ContentValues values = new ContentValues();
                values.put("course_name", courseName);
                values.put("teacher_name", teacherName);
                values.put("classroom", classroom);
                values.put("weekday", weekday);
                values.put("time", time);
                long rowId = mDatabase.insert("schedule", null, values);

                // 显示结果
                if (rowId != -1) {
                    Toast.makeText(MainActivity.this, "添加成功", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "添加失败", Toast.LENGTH_SHORT).show();
                }

                // 清空输入框
                mCourseNameEditText.setText("");
                mTeacherNameEditText.setText("");
                mClassroomEditText.setText("");
                mWeekdayEditText.setText("");
                mTimeEditText.setText("");
            }
        });

        // 查看按钮点击事件监听器
        viewButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 查询数据
                Cursor cursor = mDatabase.query("schedule", null, null, null, null, null, null);
                StringBuilder resultBuilder = new StringBuilder();
                if (cursor.moveToFirst()) {
                    do {
                        int id = cursor.getInt(cursor.getColumnIndex("_id"));
                        String courseName = cursor.getString(cursor.getColumnIndex("course_name"));
                        String teacherName = cursor.getString(cursor.getColumnIndex("teacher_name"));
                        String classroom = cursor.getString(cursor.getColumnIndex("classroom"));
                        int weekday = cursor.getInt(cursor.getColumnIndex("weekday"));
                        String time = cursor.getString(cursor.getColumnIndex("time"));
                        resultBuilder.append(String.format("%d\t%s\t%s\t%s\t%d\t%s\n", id, courseName, teacherName, classroom, weekday, time));
                    } while (cursor.moveToNext());
                }
                cursor.close();

                // 显示结果
                mScheduleTextView.setText(resultBuilder.toString());
            }
        });

        // 修改按钮点击事件监听器
        updateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String courseIdString = mCourseNameEditText.getText().toString();
                String weekdayString = mWeekdayEditText.getText().toString();
                String time = mTimeEditText.getText().toString();

                // 检查输入是否为空
                if (TextUtils.isEmpty(courseIdString) || TextUtils.isEmpty(weekdayString) || TextUtils.isEmpty(time)) {
                    Toast.makeText(MainActivity.this, "请填写完整信息", Toast.LENGTH_SHORT).show();
                    return;
                }

                // 解析课程 ID 和星期
                int courseId = Integer.parseInt(courseIdString);
                int weekday = Integer.parseInt(weekdayString);

                // 更新数据
                ContentValues values = new ContentValues();
                values.put("weekday", weekday);
                values.put("time", time);
                int rowsAffected = mDatabase.update("schedule", values, "_id=?", new String[]{String.valueOf(courseId)});

                // 显示结果
                if (rowsAffected > 0) {
                    Toast.makeText(MainActivity.this, "修改成功", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "修改失败", Toast.LENGTH_SHORT).show();
                }

                // 清空输入框
                mCourseNameEditText.setText("");
                mTeacherNameEditText.setText("");
                mClassroomEditText.setText("");
                mWeekdayEditText.setText("");
                mTimeEditText.setText("");
            }
        });
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // 关闭数据库
        mDatabase.close();
    }
}

<!-- activity_main.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="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/course_name_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="课程名称" />

    <EditText
        android:id="@+id/teacher_name_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="教师名称" />

    <EditText
        android:id="@+id/classroom_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="教室" />

    <EditText
        android:id="@+id/weekday_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="星期" />

    <EditText
        android:id="@+id/time_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="时间" />

    <Button
        android:id="@+id/add_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="添加" />

    <Button
        android:id="@+id/view_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="查看" />

    <Button
        android:id="@+id/update_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="修改" />

    <TextView
        android:id="@+id/schedule_text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="" />

</LinearLayout>