逗号拼接字符串
可以使用String类的静态方法join()来实现这个功能，示例代码如下：
```java
public class PhoneNumbers {
public static void main(String[] args) {
String phoneNumber1 = "18801083588";
String phoneNumber2 = "15709106355";
String phoneNumber3 = "18001931933";
String phoneNumberString = String.join(",", phoneNumber1, phoneNumber2, phoneNumber3);
System.out.println(phoneNumberString);
}
}
```
输出结果为：
```text
18801083576,15709106355,18001931933
```