在Androidstudio中设计一个简单学生选课系统并给出代码以及XML代码，在这个应用程序中有两个Activity界面，分别是对课程进行操作时的CourseActivity界面，以及对学生操作的PersonActivity界面。在CourseActivity界面可以对课程进行添加，删除以及跳转到PersonActivity功能和通过ListView将所有课程显示在页面上，在PersonActivity中可以对person表数据进行增、删、改等操作和通过ListView将所有学生信息显示在页面上，在这个

应用程序中，我们需要创建两个Java类和两个XML布局文件，其中一个布局文件是用于CourseActivity，另一个布局文件是用于PersonActivity。以下是详细的代码和XML文件。

CourseActivity.java:

public class CourseActivity extends AppCompatActivity {

    private ListView courseListView;
    private CourseAdapter courseAdapter;
    private List<Course> courseList;

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

        courseListView = findViewById(R.id.course_list_view);
        courseList = new ArrayList<>();

        courseAdapter = new CourseAdapter(this, R.layout.course_list_item, courseList);
        courseListView.setAdapter(courseAdapter);

        Button addCourseBtn = findViewById(R.id.add_course_btn);
        addCourseBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(CourseActivity.this, AddCourseActivity.class);
                startActivityForResult(intent, 1);
            }
        });

        courseListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Intent intent = new Intent(CourseActivity.this, PersonActivity.class);
                intent.putExtra("course_name", courseList.get(i).getName());
                startActivity(intent);
            }
        });

        courseListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, final int i, long l) {
                AlertDialog.Builder builder = new AlertDialog.Builder(CourseActivity.this);
                builder.setMessage("确定要删除此课程？")
                        .setPositiveButton("确认", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int j) {
                                courseList.remove(i);
                                courseAdapter.notifyDataSetChanged();
                            }
                        })
                        .setNegativeButton("取消", null);
                builder.create().show();
                return true;
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == 1 && resultCode == RESULT_OK) {
            String courseName = data.getStringExtra("course_name");
            int credit = data.getIntExtra("credit", 0);
            Course course = new Course(courseName, credit);
            courseList.add(course);
            courseAdapter.notifyDataSetChanged();
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}

PersonActivity.java:

public class PersonActivity extends AppCompatActivity {

    private ListView personListView;
    private PersonAdapter personAdapter;
    private List<Person> personList;

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

        personListView = findViewById(R.id.person_list_view);
        personList = new ArrayList<>();

        personAdapter = new PersonAdapter(this, R.layout.person_list_item, personList);
        personListView.setAdapter(personAdapter);

        Button addPersonBtn = findViewById(R.id.add_person_btn);
        addPersonBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(PersonActivity.this, AddPersonActivity.class);
                startActivityForResult(intent, 1);
            }
        });

        personListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, final int i, long l) {
                AlertDialog.Builder builder = new AlertDialog.Builder(PersonActivity.this);
                builder.setMessage("确定要删除此学生？")
                        .setPositiveButton("确认", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int j) {
                                personList.remove(i);
                                personAdapter.notifyDataSetChanged();
                            }
                        })
                        .setNegativeButton("取消", null);
                builder.create().show();
                return true;
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == 1 && resultCode == RESULT_OK) {
            String name = data.getStringExtra("name");
            String sex = data.getStringExtra("sex");
            int age = data.getIntExtra("age", 0);
            Person person = new Person(name, sex, age);
            personList.add(person);
            personAdapter.notifyDataSetChanged();
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}

activity_course.xml:

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

    <Button
        android:id="@+id/add_course_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="添加课程"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_marginBottom="20dp"
        android:layout_marginRight="20dp"/>

    <ListView
        android:id="@+id/course_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/add_course_btn"/>

</RelativeLayout>

course_list_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="horizontal">

    <TextView
        android:id="@+id/course_name_tv"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:textSize="18sp"
        android:textStyle="bold"
        android:padding="10dp"/>

    <TextView
        android:id="@+id/course_credit_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:textStyle="bold"
        android:padding="10dp"/>

</LinearLayout>

activity_person.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">

    <Button
        android:id="@+id/add_person_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="添加学生"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"/>

    <ListView
        android:id="@+id/person_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

person_list_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="horizontal">

    <TextView
        android:id="@+id/person_name_tv"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:textSize="18sp"
        android:textStyle="bold"
        android:padding="10dp"/>

    <TextView
        android:id="@+id/person_sex_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:textStyle="bold"
        android:padding="10dp"/>

    <TextView
        android:id="@+id/person_age_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:textStyle="bold"
        android:padding="10dp"/>

</LinearLayout>

CourseAdapter.java:

public class CourseAdapter extends ArrayAdapter<Course> {

    private int resourceId;

    public CourseAdapter(Context context, int resourceId, List<Course> objects) {
        super(context, resourceId, objects);
        this.resourceId = resourceId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Course course = getItem(position);
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.courseNameTv = view.findViewById(R.id.course_name_tv);
            viewHolder.courseCreditTv = view.findViewById(R.id.course_credit_tv);
            view.setTag(viewHolder);
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }
        viewHolder.courseNameTv.setText(course.getName());
        viewHolder.courseCreditTv.setText(String.valueOf(course.getCredit()));
        return view;
    }

    class ViewHolder {
        TextView courseNameTv;
        TextView courseCreditTv;
    }
}

PersonAdapter.java:

public class PersonAdapter extends ArrayAdapter<Person> {

    private int resourceId;

    public PersonAdapter(Context context, int resourceId, List<Person> objects) {
        super(context, resourceId, objects);
        this.resourceId = resourceId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Person person = getItem(position);
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.personNameTv = view.findViewById(R.id.person_name_tv);
            viewHolder.personSexTv = view.findViewById(R.id.person_sex_tv);
            viewHolder.personAgeTv = view.findViewById(R.id.person_age_tv);
            view.setTag(viewHolder);
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }
        viewHolder.personNameTv.setText(person.getName());
        viewHolder.personSexTv.setText(person.getSex());
        viewHolder.personAgeTv.setText(String.valueOf(person.getAge()));
        return view;
    }

    class ViewHolder {
        TextView personNameTv;
        TextView personSexTv;
        TextView personAgeTv;
    }
}

AddCourseActivity.java:

public class AddCourseActivity extends AppCompatActivity {

    private EditText courseNameEt;
    private EditText creditEt;

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

        courseNameEt = findViewById(R.id.course_name_et);
        creditEt = findViewById(R.id.credit_et);

        Button confirmBtn = findViewById(R.id.confirm_btn);
        confirmBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent();
                intent.putExtra("course_name", courseNameEt.getText().toString());
                intent.putExtra("credit", Integer.parseInt(creditEt.getText().toString()));
                setResult(RESULT_OK, intent);
                finish();
            }
        });

        Button cancelBtn = findViewById(R.id.cancel_btn);
        cancelBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
    }
}

AddPersonActivity.java:

public class AddPersonActivity extends AppCompatActivity {

    private EditText nameEt;
    private EditText sexEt;
    private EditText ageEt;

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

        nameEt = findViewById(R.id.name_et);
        sexEt = findViewById(R.id.sex_et);
        ageEt = findViewById(R.id.age_et);

        Button confirmBtn = findViewById(R.id.confirm_btn);
        confirmBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent();
                intent.putExtra("name", nameEt.getText().toString());
                intent.putExtra("sex", sexEt.getText().toString());
                intent.putExtra("age", Integer.parseInt(ageEt.getText().toString()));
                setResult(RESULT_OK, intent);
                finish();
            }
        });

        Button cancelBtn = findViewById(R.id.cancel_btn);
        cancelBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
    }
}

以上是一个简单的学生选课系统的实现，其中CourseActivity界面可以对课程进行添加、删除以及跳转到PersonActivity功能，PersonActivity界面可以对person表数据进行增、删、改等操作。