全部代码：

import java.util.Scanner;

class Contact {

String cellPhone;

String name;

}

public class Main {

private static void menu () {

System.out.println("************** 菜单 ******"

+ "************");

System.out.println(" 1.显示全部通讯录");

System.out.println(" 2.增加一条记录");

System.out.println(" 3.删除一条记录");

System.out.println(" 4.修改一条记录");

System.out.println(" 0.退出");

}

public static void main(String[] args) {

Scanner scn = new Scanner(System.in);

Contact[] contacts = new Contact[200];

int size = 0;

String cmd = "";

do {

menu();

System.out.print("请输入你得选择：(0-4)");

cmd = scn.nextLine();

if (cmd.equals("1")) {

if (size == 0)

System.out.println("系统当前无记录！");

else

for (int i = 0; i < size; i++) {

System.out.println(contacts[i].name + ":"

+ contacts[i].cellPhone);

}

} else if (cmd.equals("2")) {

System.out.print("请输入手机号：");

String cellphone = scn.nextLine();

System.out.print("请输入姓名：");

String name = scn.nextLine();

Contact contact = new Contact();

contact.cellPhone = cellphone;

contact.name = name;

if (size < contacts.length) {

contacts[size++] = contact;

System.out.println("添加成功！");

} else {

System.out.println("你最多只能添加" +

contacts.length + "条记录");

}

} else if (cmd.equals("3")) {

System.out.print("请输入要删除的手机号：");

String cellphone = scn.nextLine();

int index = -1;

for (int i = 0; i < size && i < contacts.length;

i++) {

if (contacts[i].cellPhone.equals(cellphone)) {

index = i;

break;

}

}

if (index == -1) {

System.out.println("该记录不存在！");

} else {

for (int i = index; i < size; i++) {

contacts[index] = contacts[index + 1];

}

contacts[size - 1] = null;

size--;

System.out.println("删除成功！");

}

} else if (cmd.equals("4")) {

System.out.print("请输入要修改的手机号：");

String cellphone = scn.nextLine();

int index = -1;

for (int i = 0; i < size && i < contacts.length;

i++) {

if (contacts[i].cellPhone.equals(cellphone)) {

index = i;

break;

}

}

if (index == -1) {

System.out.println("该记录不存在！");

} else {

System.out.print("请输入姓名：");

String name = scn.nextLine();

contacts[index].name = name;

}

}

} while (!cmd.equals("0"));

System.out.println("退出成功！");

scn.close();

System.exit(0);

}

}