初识JAVA

//studen类

public class Student {

public String name;
public String sex;
public int age;
public long num;
public int QQ;
public String adress;

public Student() {
super();
// TODO 自动生成的构造函数存根
}


public Student(String name,String sex,int age,long num,int QQ,String adress){
this.name=name;
this.sex=sex;
this.age=age;
this.QQ=QQ;
this.num=num;
this.adress=adress;

}

@Override
public String toString() {
return "Student [名字=" + name + ", 性别=" + sex + ", 年龄=" + age
+ ", 手机号=" + num + ", QQ=" + QQ + ", 地址=" + adress + "]";
}

}

//实现对学生资料的管理

import java.util.Scanner;




public class Num {
static Student[] student=new Student[50];
static Scanner sc=new Scanner(System.in);
 
static Student s;


public static void main(String[] args)  {
// TODO Auto-generated method stub
int n=0;
do{
System.out.println("----------------电话管理系统------------");
System.out.println("1.添加\t2.删除\t3.修改\t4.查询所有\t5.根据姓名查询\t0.退出");
System.out.println("----------------电话管理系统------------");
student[0]=new Student("王二","男",22,123124,312421,"sd");
student[1]=new Student("李四","男",22,123124,312421,"sd");
student[2]=new Student("张三","男",22,123124,312421,"sd");

n=sc.nextInt();
switch(n){


case 1:
add();break;
case 2:
delete();break;
case 3:chage();break;
case 4:find();break;
case 5:find1();break;

default:
System.out.println("输入错误，重新输入");
break;
}
}while(n!=0);
}


public static void add(){
s=new Student();
for(int i=0;i<50;i++){
if(student[i]==null){


System.out.println("依次输入学生信息");
System.out.println("姓名：");
s.name=sc.next();
System.out.println("性别：");
s.sex=sc.next();
System.out.println("年龄：");
s.age=sc.nextInt();
System.out.println("电话：");
s.num=sc.nextInt();
System.out.println("QQ：");
s.QQ=sc.nextInt();
System.out.println("地址：");
s.adress=sc.next();
student[i]=s;
System.out.println("添加的学生信息为："+student[i]);

break;}
}
  
}
public static void delete(){
System.out.println("请输入要删除的人名：");
String na=sc.next();
int a=0;

for(int i=0;i<student.length;i++){
if(student[i].name.equals(na)){
a=i;
break;
}
}
System.out.println(student[a]+"已删除");
student[a]=new Student("null","null",0,0,0,"null");
 
}
public static void chage(){
System.out.println("请输入要修改人的姓名:");
String na=sc.next();
int a=0;

for(int i=0;i<student.length;i++){
if(student[i].name.equals(na)){
a=i;break;
}
}
System.out.println(student[a]+"\n已找到");
System.out.println("依次输入学生信息");
System.out.print("姓名：");
s.name=sc.next();
System.out.println("haha");
System.out.print("性别：");
s.sex=sc.next();
System.out.print("年龄：");
s.age=sc.nextInt();
System.out.print("电话：");
s.num=sc.nextInt();
System.out.print("QQ：");
s.QQ=sc.nextInt();
System.out.print("地址：");
s.adress=sc.next();
student[a]=s;
System.out.println("学生的信息更改为："+student[a]);
 
 
}
public static void find(){
for(int i=0;i<50;i++){
if(student[i]!=null){
System.out.println(student[i]);
}
else 
break;
}

}

public static void find1(){
System.out.println("请输入要修要查找人的姓名:");
String na=sc.next();
int a=0;

for(int i=0;i<student.length;i++){
if(student[i].name.equals(na)){
a=i;break;
}
}

}
}

初学java遇到很多问题，但是java代码真的很强大，能实现好多功能。