Android studio的登录代码，登录后跳到一个新界面，新界面为一张课程表，课程表的布局使用gridview控件，并且控件下面有三个按钮，能对课程表做出修改，删除，查询，修改界面能修改课程时间，地点以及添加课程名称，课程时间，课程地点，删除界面能删除选定课程，并且更新修改后的课程表

以下是一个简单的 Android Studio 登录代码，登录成功后跳转到一个新界面，新界面包含一个 GridView 控件和三个按钮，用于对课程表进行修改、删除和查询：

public class LoginActivity extends AppCompatActivity {

    private EditText usernameEditText;
    private EditText passwordEditText;

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

        usernameEditText = findViewById(R.id.username_edit_text);
        passwordEditText = findViewById(R.id.password_edit_text);

        Button loginButton = findViewById(R.id.login_button);
        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = usernameEditText.getText().toString().trim();
                String password = passwordEditText.getText().toString().trim();

                // 检查用户名和密码是否正确
                if (username.equals("admin") && password.equals("123456")) {
                    Intent intent = new Intent(LoginActivity.this, CourseTableActivity.class);
                    startActivity(intent);
                } else {
                    Toast.makeText(LoginActivity.this, "用户名或密码不正确", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

在 CourseTableActivity 中，我们可以使用一个 GridView 控件来展示课程表。以下是一个示例代码：

public class CourseTableActivity extends AppCompatActivity {

    private GridView gridView;
    private ArrayList<Course> courseList;
    private CourseAdapter courseAdapter;

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

        // 初始化课程表数据
        courseList = new ArrayList<>();
        courseList.add(new Course("数学", "周一 1-2节", "教学楼101"));
        courseList.add(new Course("英语", "周二 3-4节", "教学楼201"));
        courseList.add(new Course("物理", "周三 5-6节", "教学楼301"));
        courseList.add(new Course("化学", "周四 7-8节", "教学楼401"));
        courseList.add(new Course("计算机", "周五 9-10节", "教学楼501"));

        // 初始化 GridView 控件
        gridView = findViewById(R.id.grid_view);
        courseAdapter = new CourseAdapter(this, courseList);
        gridView.setAdapter(courseAdapter);

        // 初始化按钮点击事件
        Button modifyButton = findViewById(R.id.modify_button);
        modifyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 跳转到修改课程界面
            }
        });

        Button deleteButton = findViewById(R.id.delete_button);
        deleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 跳转到删除课程界面
            }
        });

        Button queryButton = findViewById(R.id.query_button);
        queryButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 跳转到查询课程界面
            }
        });
    }

    private static class CourseAdapter extends BaseAdapter {

        private Context context;
        private ArrayList<Course> courseList;

        public CourseAdapter(Context context, ArrayList<Course> courseList) {
            this.context = context;
            this.courseList = courseList;
        }

        @Override
        public int getCount() {
            return courseList.size();
        }

        @Override
        public Object getItem(int position) {
            return courseList.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = LayoutInflater.from(context).inflate(R.layout.item_course, parent, false);
            }

            TextView nameTextView = convertView.findViewById(R.id.name_text_view);
            TextView timeTextView = convertView.findViewById(R.id.time_text_view);
            TextView locationTextView = convertView.findViewById(R.id.location_text_view);

            Course course = courseList.get(position);
            nameTextView.setText(course.getName());
            timeTextView.setText(course.getTime());
            locationTextView.setText(course.getLocation());

            return convertView;
        }
    }
}

在 CourseTableActivity 中，我们还需要添加修改、删除和查询课程的方法。具体实现方式可以根据具体需求进行设计，以下是一个简单的示例代码：

public class CourseTableActivity extends AppCompatActivity {

    // ...

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

        // ...

        // 初始化按钮点击事件
        Button modifyButton = findViewById(R.id.modify_button);
        modifyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 跳转到修改课程界面
                Intent intent = new Intent(CourseTableActivity.this, ModifyCourseActivity.class);
                startActivity(intent);
            }
        });

        Button deleteButton = findViewById(R.id.delete_button);
        deleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 跳转到删除课程界面
                Intent intent = new Intent(CourseTableActivity.this, DeleteCourseActivity.class);
                startActivityForResult(intent, DELETE_COURSE_REQUEST_CODE);
            }
        });

        Button queryButton = findViewById(R.id.query_button);
        queryButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 跳转到查询课程界面
                Intent intent = new Intent(CourseTableActivity.this, QueryCourseActivity.class);
                startActivity(intent);
            }
        });
    }

    // 处理删除课程后的回调
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == DELETE_COURSE_REQUEST_CODE && resultCode == RESULT_OK) {
            // 更新课程表数据
            courseList.clear();
            courseList.addAll((ArrayList<Course>) data.getSerializableExtra("courseList"));
            courseAdapter.notifyDataSetChanged();
        }
    }

    // ...
}

在 ModifyCourseActivity、DeleteCourseActivity 和 QueryCourseActivity 中，我们可以实现具体的修改、删除和查询课程的逻辑。以下是一个简单的示例代码：

public class ModifyCourseActivity extends AppCompatActivity {

    private EditText nameEditText;
    private EditText timeEditText;
    private EditText locationEditText;

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

        nameEditText = findViewById(R.id.name_edit_text);
        timeEditText = findViewById(R.id.time_edit_text);
        locationEditText = findViewById(R.id.location_edit_text);

        Button modifyButton = findViewById(R.id.modify_button);
        modifyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 修改课程信息
            }
        });
    }
}

public class DeleteCourseActivity extends AppCompatActivity {

    private GridView gridView;
    private ArrayList<Course> courseList;
    private CourseAdapter courseAdapter;

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

        // 初始化课程表数据
        courseList = new ArrayList<>();
        courseList.add(new Course("数学", "周一 1-2节", "教学楼101"));
        courseList.add(new Course("英语", "周二 3-4节", "教学楼201"));
        courseList.add(new Course("物理", "周三 5-6节", "教学楼301"));
        courseList.add(new Course("化学", "周四 7-8节", "教学楼401"));
        courseList.add(new Course("计算机", "周五 9-10节", "教学楼501"));

        // 初始化 GridView 控件
        gridView = findViewById(R.id.grid_view);
        courseAdapter = new CourseAdapter(this, courseList);
        gridView.setAdapter(courseAdapter);

        Button deleteButton = findViewById(R.id.delete_button);
        deleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 删除选定课程
                SparseBooleanArray selectedItems = gridView.getCheckedItemPositions();
                ArrayList<Course> selectedCourses = new ArrayList<>();
                for (int i = 0; i < selectedItems.size(); i++) {
                    int position = selectedItems.keyAt(i);
                    if (selectedItems.valueAt(i)) {
                        selectedCourses.add(courseList.get(position));
                    }
                }
                courseList.removeAll(selectedCourses);
                courseAdapter.notifyDataSetChanged();

                // 返回结果并关闭当前界面
                Intent intent = new Intent();
                intent.putExtra("courseList", courseList);
                setResult(RESULT_OK, intent);
                finish();
            }
        });
    }

    // ...
}

public class QueryCourseActivity extends AppCompatActivity {

    private EditText nameEditText;

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

        nameEditText = findViewById(R.id.name_edit_text);

        Button queryButton = findViewById(R.id.query_button);
        queryButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = nameEditText.getText().toString().trim();

                // 查询课程信息
                // ...

                // 返回查询结果并关闭当前界面
                Intent intent = new Intent();
                intent.putExtra("courseList", courseList);
                setResult(RESULT_OK, intent);
                finish();
            }
        });
    }
}