目标：完成一个 JAVA Application 应用开发：时钟日历 ，要求实现待办项功能：支持在日历中添加代办项，允许用户在日历中的某一天中插入一定数量的待办项，而后用户 可以勾选这些待办项是否完成，以及增删代办项。

好的，以下是一个简单的实现示例，供您参考：

1. 创建GUI界面

可以使用Java Swing或JavaFX来创建GUI界面，这里以JavaFX为例。界面中包含一个时钟模块、一个日历模块和一个待办项列表，以及添加、删除待办项的按钮。

public class ClockCalendarApp extends Application {
    private Label clockLabel;
    private DatePicker calendar;
    private ListView<TodoItem> todoList;

    @Override
    public void start(Stage primaryStage) {
        // 创建界面组件
        clockLabel = new Label();
        calendar = new DatePicker();
        todoList = new ListView<>();
        Button addButton = new Button("添加");
        Button deleteButton = new Button("删除");

        // 设置界面布局
        VBox layout = new VBox();
        layout.getChildren().addAll(clockLabel, calendar, todoList, addButton, deleteButton);
        Scene scene = new Scene(layout, 400, 400);

        // 显示界面
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}

2. 实现时钟模块

可以使用Java的Timeline类来实现定时更新界面上的时钟。

    @Override
    public void start(Stage primaryStage) {
        // ...

        // 更新时钟
        Timeline timeline = new Timeline(new KeyFrame(Duration.seconds(1), event -> {
            clockLabel.setText(new SimpleDateFormat("HH:mm:ss").format(new Date()));
        }));
        timeline.setCycleCount(Timeline.INDEFINITE);
        timeline.play();
    }

3. 实现日历模块

可以监听DatePicker的日期变化事件来更新日历显示。

    @Override
    public void start(Stage primaryStage) {
        // ...

        // 更新日历
        calendar.setOnAction(event -> {
            LocalDate date = calendar.getValue();
            System.out.println("Selected date: " + date);
        });
    }

4. 实现待办项的添加和删除功能

可以使用Java的ObservableList和Map来存储待办项，其中Map的键为日期，值为该日期下的所有待办项。

public class TodoItem {
    private String content;
    private boolean completed;

    public TodoItem(String content) {
        this.content = content;
        this.completed = false;
    }

    public String getContent() {
        return content;
    }

    public boolean isCompleted() {
        return completed;
    }

    public void setCompleted(boolean completed) {
        this.completed = completed;
    }
}

public class ClockCalendarApp extends Application {
    // ...

    private ObservableList<TodoItem> todoItems;
    private Map<LocalDate, List<TodoItem>> todoMap;

    @Override
    public void start(Stage primaryStage) {
        // ...

        // 初始化待办项列表和Map
        todoItems = FXCollections.observableArrayList();
        todoMap = new HashMap<>();

        // 添加待办项
        addButton.setOnAction(event -> {
            LocalDate date = calendar.getValue();
            if (date == null) {
                System.out.println("请先选择日期！");
                return;
            }
            TextInputDialog dialog = new TextInputDialog();
            dialog.setTitle("添加待办项");
            dialog.setHeaderText("请输入待办项内容：");
            Optional<String> result = dialog.showAndWait();
            result.ifPresent(content -> {
                TodoItem todoItem = new TodoItem(content);
                todoItems.add(todoItem);
                List<TodoItem> todoList = todoMap.getOrDefault(date, new ArrayList<>());
                todoList.add(todoItem);
                todoMap.put(date, todoList);
            });
        });

        // 删除待办项
        deleteButton.setOnAction(event -> {
            TodoItem selected = todoList.getSelectionModel().getSelectedItem();
            if (selected == null) {
                System.out.println("请先选择待办项！");
                return;
            }
            LocalDate date = calendar.getValue();
            todoItems.remove(selected);
            List<TodoItem> todoList = todoMap.get(date);
            todoList.remove(selected);
            if (todoList.isEmpty()) {
                todoMap.remove(date);
            }
        });

        // 绑定待办项列表
        todoList.setItems(todoItems);
        todoList.setCellFactory(param -> new ListCell<>() {
            @Override
            protected void updateItem(TodoItem item, boolean empty) {
                super.updateItem(item, empty);
                if (empty || item == null) {
                    setText(null);
                } else {
                    setText(item.getContent() + (item.isCompleted() ? " (已完成)" : ""));
                }
            }
        });

        // 勾选待办项
        todoList.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue != null) {
                newValue.setCompleted(!newValue.isCompleted());
                todoList.refresh();
            }
        });
    }
}

5. 实现保存和读取待办项的功能

可以使用Java的文件读写API来实现，比如将待办项存储在一个文本文件中。

    @Override
    public void stop() throws Exception {
        // 保存待办项
        try (PrintWriter writer = new PrintWriter(new FileWriter("todo.txt"))) {
            for (Map.Entry<LocalDate, List<TodoItem>> entry : todoMap.entrySet()) {
                LocalDate date = entry.getKey();
                List<TodoItem> todoList = entry.getValue();
                for (TodoItem todoItem : todoList) {
                    writer.printf("%s\t%s\t%s\n", date, todoItem.getContent(), todoItem.isCompleted());
                }
            }
        }
    }

    @Override
    public void start(Stage primaryStage) {
        // ...

        // 读取待办项
        try (Scanner scanner = new Scanner(new File("todo.txt"))) {
            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                String[] parts = line.split("\t");
                LocalDate date = LocalDate.parse(parts[0]);
                String content = parts[1];
                boolean completed = Boolean.parseBoolean(parts[2]);
                TodoItem todoItem = new TodoItem(content);
                todoItem.setCompleted(completed);
                todoItems.add(todoItem);
                List<TodoItem> todoList = todoMap.getOrDefault(date, new ArrayList<>());
                todoList.add(todoItem);
                todoMap.put(date, todoList);
            }
        } catch (FileNotFoundException e) {
            // 文件不存在，忽略
        }
    }

6. 完整的代码示例

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.util.*;

public class ClockCalendarApp extends Application {
    private Label clockLabel;
    private DatePicker calendar;
    private ListView<TodoItem> todoList;
    private ObservableList<TodoItem> todoItems;
    private Map<LocalDate, List<TodoItem>> todoMap;

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) {
        // 创建界面组件
        clockLabel = new Label();
        calendar = new DatePicker();
        todoList = new ListView<>();
        Button addButton = new Button("添加");
        Button deleteButton = new Button("删除");

        // 设置界面布局
        VBox layout = new VBox();
        layout.getChildren().addAll(clockLabel, calendar, todoList, addButton, deleteButton);
        Scene scene = new Scene(layout, 400, 400);

        // 更新时钟
        Timeline timeline = new Timeline(new KeyFrame(Duration.seconds(1), event -> {
            clockLabel.setText(new SimpleDateFormat("HH:mm:ss").format(new Date()));
        }));
        timeline.setCycleCount(Timeline.INDEFINITE);
        timeline.play();

        // 更新日历
        calendar.setOnAction(event -> {
            LocalDate date = calendar.getValue();
            System.out.println("Selected date: " + date);
        });

        // 初始化待办项列表和Map
        todoItems = FXCollections.observableArrayList();
        todoMap = new HashMap<>();

        // 添加待办项
        addButton.setOnAction(event -> {
            LocalDate date = calendar.getValue();
            if (date == null) {
                System.out.println("请先选择日期！");
                return;
            }
            TextInputDialog dialog = new TextInputDialog();
            dialog.setTitle("添加待办项");
            dialog.setHeaderText("请输入待办项内容：");
            Optional<String> result = dialog.showAndWait();
            result.ifPresent(content -> {
                TodoItem todoItem = new TodoItem(content);
                todoItems.add(todoItem);
                List<TodoItem> todoList = todoMap.getOrDefault(date, new ArrayList<>());
                todoList.add(todoItem);
                todoMap.put(date, todoList);
            });
        });

        // 删除待办项
        deleteButton.setOnAction(event -> {
            TodoItem selected = todoList.getSelectionModel().getSelectedItem();
            if (selected == null) {
                System.out.println("请先选择待办项！");
                return;
            }
            LocalDate date = calendar.getValue();
            todoItems.remove(selected);
            List<TodoItem> todoList = todoMap.get(date);
            todoList.remove(selected);
            if (todoList.isEmpty()) {
                todoMap.remove(date);
            }
        });

        // 绑定待办项列表
        todoList.setItems(todoItems);
        todoList.setCellFactory(param -> new ListCell<>() {
            @Override
            protected void updateItem(TodoItem item, boolean empty) {
                super.updateItem(item, empty);
                if (empty || item == null) {
                    setText(null);
                } else {
                    setText(item.getContent() + (item.isCompleted() ? " (已完成)" : ""));
                }
            }
        });

        // 勾选待办项
        todoList.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue != null) {
                newValue.setCompleted(!newValue.isCompleted());
                todoList.refresh();
            }
        });

        // 读取待办项
        try (Scanner scanner = new Scanner(new File("todo.txt"))) {
            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                String[] parts = line.split("\t");
                LocalDate date = LocalDate.parse(parts[0]);
                String content = parts[1];
                boolean completed = Boolean.parseBoolean(parts[2]);
                TodoItem todoItem = new TodoItem(content);
                todoItem.setCompleted(completed);
                todoItems.add(todoItem);
                List<TodoItem> todoList = todoMap.getOrDefault(date, new ArrayList<>());
                todoList.add(todoItem);
                todoMap.put(date, todoList);
            }
        } catch (FileNotFoundException e) {
            // 文件不存在，忽略
        }

        // 保存待办项
        primaryStage.setOnCloseRequest(event -> {
            try (PrintWriter writer = new PrintWriter(new FileWriter("todo.txt"))) {
                for (Map.Entry<LocalDate, List<TodoItem>> entry : todoMap.entrySet()) {
                    LocalDate date = entry.getKey();
                    List<TodoItem> todoList = entry.getValue();
                    for (TodoItem todoItem : todoList) {
                        writer.printf("%s\t%s\t%s\n", date, todoItem.getContent(), todoItem.isCompleted());
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        });

        // 显示界面
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static class TodoItem {
        private String content;
        private boolean completed;

        public TodoItem(String content) {
            this.content = content;
            this.completed = false;
        }

        public String getContent() {
            return content;
        }

        public boolean isCompleted() {
            return completed;
        }

        public void setCompleted(boolean completed) {
            this.completed = completed;
        }
    }
}