class Book{?private String title;?private int price;??public Book(String title,int price){???? //構(gòu)造器??this.title=title;??this.price=price;?}?public String getTitle() {??return title;?}?public void setTitle(String title) {??this.title = title;?}?public int getPrice() {??return price;?}?public void setPrice(int price) {??this.price = price;?}??public boolean equals(Object obj){??if(this==obj){???? //比較地址是否相同???return true;??}??if(obj==null){???? //判斷要比較的對(duì)象是否為空???return false;??}??if(!(obj instanceof Book)){// 判斷數(shù)據(jù)類型是否一樣???return false;??}??Book book=(Book) obj;? //強(qiáng)轉(zhuǎn)數(shù)據(jù)類型??if(this.title.equals(book.title)&&????this.price==book.price){?? //自定義比較規(guī)則???return true;??}else {???return false;??}??}?@Override?public String toString() {??return "Book [title=" + title + ", price=" + price + "]";?}??}?public class EqualsTest {?public static void main(String[] args) {??Book book1=new Book("java",20);??Book book2=new Book("java",21);??System.out.println(book1.equals(book2));??book1.toString();??book2.toString();???}?}?