@Override public String toString()

这是一个 Java 语言中的方法，用于将对象转换为字符串并返回该字符串。通常情况下，这个方法会被重写，以便返回有意义的字符串描述对象的状态。例如：

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "Person{name='" + name + "', age=" + age + "}";
    }
}

在上面的例子中，我们重写了 `toString()` 方法，以便返回一个包含对象名称、姓名和年龄的字符串。这样就可以方便地打印出 Person 对象的信息了：

Person p = new Person("Alice", 25);
System.out.println(p); // 输出：Person{name='Alice', age=25}

相关问题

class Contact { protected String name; protected String phone; protected String remark; public Contact(String name, String phone, String remark) { this.name = name; this.phone = phone; this.remark = remark; } public void display() { System.out.println(toString()); } @Override public String toString() { return "姓名：" + name + "，电话：" + phone + "，备注：" + remark; } } class Family extends Contact { private String address; private String homePhone; public Family(String name, String phone, String remark, String address, String homePhone) { super(name, phone, remark); this.address = address; this.homePhone = homePhone; } @Override public void display() { System.out.println(toString()); } @Override public String toString() { return super.toString() + "，地址：" + address + "，固定电话：" + homePhone; } } class Friend extends Contact { private String category; public Friend(String name, String phone, String remark, String category) { super(name, phone, remark); this.category = category; } @Override public void display() { System.out.println(toString()); } @Override public String toString() { return super.toString() + "，类别：" + category; } } class WorkContact extends Contact { private String company; private String department; private String position; public WorkContact(String name, String phone, String remark, String company, String department, String position) { super(name, phone, remark); this.company = company; this.department = department; this.position = position; } @Override public void display() { System.out.println(toString()); } @Override public String toString() { return super.toString() + "，公司：" + company + "，部门：" + department + "，职务：" + position; } }此程序的UML图怎么画

以下是此程序的UML图：

+------------------+
|     Contact      |
+------------------+
| - name: String    |
| - phone: String   |
| - remark: String  |
+------------------+
| + Contact(name: String, phone: String, remark: String) |
| + display(): void |
| + toString(): String |
+------------------+

        ^
        |
        |
+-------+-------+
|               |
|               |
|               |
|               |
|               |
|               |
|               |
|               |
|               |
|               |
|               |
|               |
|     Family    |      +-----------+
|               |      | WorkContact|
|               |      +-----------+
|               |              ^
|               |              |
|               |              |
|               |              |
|               |              |
|               |              |
|               |              |
|               |              |
|               |              |
|               |              |
|               |              |
+---------------+              |
| - address: String            |
| - homePhone: String          |
+---------------+              |
| + Family(name: String, phone: String, remark: String, address: String, homePhone: String) |
| + display(): void |
| + toString(): String |
+---------------+              |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                                 |
                        +--------+--------+
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |               |
                        |    Friend     |
                        |               |
                        +---------------+
                        | - category: String |
                        +---------------+
                        | + Friend(name: String, phone: String, remark: String, category: String) |
                        | + display(): void |
                        | + toString(): String |
                        +---------------+

@Override public String toString() { return cases +"\t"+ deaths; }

这是Java中的一个重写toString()方法，它的作用是将该对象的属性cases和deaths转化为String类型并返回。在该方法中，将属性cases和deaths转换成字符串并用制表符"\t"分隔，然后将它们拼接成一个字符串并返回。如果需要在程序中输出该对象的字符串形式，就可以直接调用该方法。