我正在尝试创建一个待办事项列表程序，但在寻找通过搜索特定项来删除元素的方法时遇到了一些问题。
我正试图实现 indexOf() 它将返回一个元素的索引，该元素包含在项目的arraylist中搜索的项目，但它只返回-1，而不是found。
我在todo类中重载了函数，并在item类中重载了equals（object o）和hashcode（）。
任何帮助都将不胜感激。

import java.util.*;
import java.lang.*;

public class ToDo {

    ArrayList<Item> TodoList = new ArrayList<>();

    static String [] itemData = new String[100];       //to index items added to list
    //itemData = new String[100];
    static int size=0;

    public void addItem(String item, String category, int priority)
    {
        TodoList.add(new Item(item,category,priority));
        itemData[size] = item;  //for indexing
        size++;
    }

    //remove item at specified index spot
    private void removeItem(int i )
    {

        TodoList.remove(i);

    }

    public void getList()
    {
        for (Item item : TodoList)
        {
            System.out.println(item.toString());
        }
    }

    public int getIndex(String item)
    {
        return (TodoList.indexOf(item));

    }

    public int indexOf(Object o) {
        if (o == null) {
            for (int i = 0; i < size; i++)
                if (itemData[i]==null)
                    return i;
        } else {
            for (int i = 0; i < size; i++)
                if (o.equals(itemData[i]))
                    return i;
        }
        return -1;
    }

    public void print() {
        System.out.println("To-do List: ");
        System.out.println("-----------");
        getList();
        if (TodoList == null) {
            System.out.println("You're all done for today!");
        }
    }

    public static void main(String[] args) {

        ToDo todo = new ToDo();

        todo.addItem("Get pickles", "Shopping", 2);
        todo.addItem("Read book", "School", 3);
        todo.addItem("Send letter", "Other", 1);
        todo.addItem("Buy planner", "School", 4);
        todo.addItem("Get potatoes", "Shopping", 3);
        todo.print();

        System.out.println("------------");
        //todo.removeItem("Read book","School","3");
        //todo.removeItem(1);

        System.out.println("INDEX OF READ BOOK (1) :" + todo.getIndex("ReadBook"));

        //todo.removeItem(todo.getIndex("ReadBook"));
        //todo.print();

        System.out.println("SIZE: " + size);

    }

}

public class Item {

    public int i;
    private String item;
    private String category;
    private int priority;

    //default constructor to initialize
    public Item(String item, String category, int priority){
        this.item = item;
        this.category = category;
        this.priority = priority;
    }

    public String getItem() {
        return item;
    }

    public void setItem(String item) {
        this.item = item;
    }

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public void setPriority(int priority) {
        this.priority = priority;
    }

    public int getPriority() {
        return priority;
    }

    //used in order to overload indexOf() method
    //*****************************************************
    @Override
    public boolean equals(Object o) {
        if (o instanceof Item) {
            //item comparison
            Item mo = (Item)o;
            return mo.item.equals(item);
        }
        return false;
    }

    public int hashCode() {
        return java.util.Objects.hashCode(item);
    }

    //*****************************************************

    public String translatePriority()
    {
        if (priority == 1)
            return "low";
        else if (priority == 2)
            return "medium";
        else if (priority == 3)
            return "high";
        else if (priority == 4)
            return "urgent";
        else
            return "invalid priority";

    }

    public String toString() {
        return  "Category : " + category + " || Priority Level: " + translatePriority() + "\nTask : " + item + "\n";
    }

}