Day08
昨日回顾
案例演示
1.学生类
class Demo1_Student
{
public static void main ( String[ ] args)
{
Student s1 = new Student ( ) ;
s1. setName ( "李四" ) ;
s1. setAge ( 25 ) ;
System. out. println ( "此人姓名是" + s1. getName ( ) + ",此人年龄是" + s1. getAge ( ) ) ;
System. out. println ( "------------" ) ;
Student s2 = new Student ( "张三" , 23 ) ;
s2. show ( ) ;
}
}
class Student
{
private String name;
private int age;
public Student ( ) { }
public Student ( String name , int age) {
this . name = name ;
this . age = age;
}
public void setName ( String name) {
this . name = name;
}
public String getName ( ) {
return name;
}
public void setAge ( int age) {
this . age = age;
}
public int getAge ( ) {
return age;
}
public void show ( ) {
System. out. println ( "此人姓名是" + name + ",此人年龄是" + age) ;
}
}
2.手机类
class Demo2_Phone
{
public static void main ( String[ ] args)
{
Phone p1 = new Phone ( ) ;
p1. setBrand ( "锤子" ) ;
p1. setPrice ( 1499 ) ;
System. out. println ( "手机品牌是" + p1. getBrand ( ) + ",价格是" + p1. getPrice ( ) ) ;
System. out. println ( "-----------------" ) ;
Phone p2 = new Phone ( "红米note7" , 1499 ) ;
p2. show ( ) ;
}
}
class Phone {
private String brand;
private int price;
public Phone ( ) { } ;
public Phone ( String brand, int price) {
this . brand = brand;
this . price = price;
}
public void setBrand ( String brand)
{
this . brand = brand;
}
public String getBrand ( ) {
return brand;
}
public void setPrice ( int price) {
this . price = price ;
}
public int getPrice ( ) {
return this . price;
}
public void show ( ) {
System. out. println ( "手机品牌是" + brand + ",价格是" + price) ;
}
}
面向对象
创建一个对象的步骤
class Demo3_Student {
public static void main ( String[ ] args) {
Student s = new Student ( ) ;
s. show ( ) ;
}
}
class Student {
private String name = "张三" ;
private int age = 23 ;
public Student ( ) {
name = "李四" ;
age = 24 ;
}
public void show ( ) {
System. out. println ( name + "..." + age) ;
}
}
作业案例
import java. util. Scanner;
class Test1_Rectangle {
public static void main ( String[ ] args) {
Scanner sc = new Scanner ( System. in) ;
Rectangle r = new Rectangle ( ) ;
System. out. println ( "请输入矩形的长" ) ;
int width = sc. nextInt ( ) ;
r. setWidth ( width) ;
System. out. println ( "请输入矩形的宽" ) ;
int height = sc. nextInt ( ) ;
r. setHeight ( height) ;
System. out. println ( "矩形的周长是" + r. getLength ( ) ) ;
System. out. println ( "矩形的面积是" + r. getArea ( ) ) ;
}
}
class Rectangle {
private int height;
private int width;
public Rectangle ( ) { } ;
public Rectangle ( int width, int height) {
this . width = width;
this . height = height;
}
public void setWidth ( int width) {
this . width = width;
}
public int getWidth ( ) {
return width;
}
public void setHeight ( int height) {
this . height = height;
}
public int getHeight ( ) {
return height;
}
public int getLength ( ) {
int length = ( this . width + this . height) * 2 ;
return length;
}
public int getArea ( ) {
int area = this . width * this . height ;
return area;
}
}
class Test2_Employee {
public static void main ( String[ ] args) {
Employee e1 = new Employee ( ) ;
e1. setName ( "王麻子" ) ;
e1. setId ( "A16235" ) ;
e1. setSalary ( 20000 ) ;
System. out. println ( "员工姓名是" + e1. getName ( ) + ",工号是" + e1. getId ( ) + ",薪资是" + e1. getSalary ( ) ) ;
System. out. println ( "----------------" ) ;
Employee e2 = new Employee ( "黄俊" , "0103597" , 15000 ) ;
e2. show ( ) ;
}
}
class Employee {
private String name;
private String id;
private int salary;
public Employee ( ) { } ;
public Employee ( String name, String id, int salary) {
this . name = name;
this . id = id;
this . salary = salary;
}
public void setName ( String name) {
this . name = name;
}
public String getName ( ) {
return this . name;
}
public void setId ( String id) {
this . id = id;
}
public String getId ( ) {
return id;
}
public void setSalary ( int salary) {
this . salary = salary;
}
public int getSalary ( ) {
return salary;
}
public void show ( ) {
System. out. println ( "员工姓名是" + name + ",工号是" + id + ",薪资是" + salary) ;
}
}
static 关键字
class Demo2_Static {
public static void main ( String[ ] args) {
Demo. print ( ) ;
}
}
class Demo {
int num1 = 10 ;
static int num2 = 20 ;
public void print1 ( ) {
System. out. println ( num1) ;
System. out. println ( num2) ;
}
public static void print ( ) {
System. out. println ( num2) ;
}
}
静态
静态变量和成员变量的区别
main方法的格式详解
class Demo3_Main {
public static void main ( String[ ] args) {
System. out. println ( args. length) ;
for ( int i = 0 ; i < args. length ; i++ ) {
System. out. println ( args[ i] ) ;
}
}
}
工具类中使用静态
class ArrayTool {
private ArrayTool ( ) { } ;
public static int getMax ( int [ ] arr) {
int max = arr[ 0 ] ;
for ( int i = 1 ; i < arr. length ; i++ ) {
if ( arr[ i] > max ) {
max = arr[ i] ;
}
}
return max;
}
public static void print ( int [ ] arr) {
for ( int i = 0 ; i < arr. length ; i++ ) {
System. out. print ( arr[ i] + " " ) ;
}
}
public static void reverse ( int [ ] arr) {
for ( int i = 0 ; i < arr. length/ 2 ; i++ ) {
int temp = arr[ i] ;
arr[ i] = arr[ arr. length- i- 1 ] ;
arr[ arr. length- i- 1 ] = temp;
}
}
}
class Demo_ArrayTool {
public static void main ( String[ ] args) {
int [ ] arr = { 33 , 11 , 22 , 55 , 44 } ;
ArrayTool. print ( arr) ;
}
}
说明书的制作过程
A: 对工具类加入文档注释;
B: 通过javadoc命令生成说明书;
* @author ( 提取作者内容)
* @version ( 提取版本内容)
javadoc - d 指定的文件目录 - author - version ArrayTool, java
* @param 参数名称
* @return 函数运行完返回的数据
public class ArrayTool {
private ArrayTool ( ) { } ;
public static int getMax ( int [ ] arr) {
int max = arr[ 0 ] ;
for ( int i = 1 ; i < arr. length ; i++ ) {
if ( arr[ i] > max ) {
max = arr[ i] ;
}
}
return max;
}
public static void print ( int [ ] arr) {
for ( int i = 0 ; i < arr. length ; i++ ) {
System. out. print ( arr[ i] + " " ) ;
}
}
public static void reverse ( int [ ] arr) {
for ( int i = 0 ; i < arr. length/ 2 ; i++ ) {
int temp = arr[ i] ;
arr[ i] = arr[ arr. length- i- 1 ] ;
arr[ arr. length- i- 1 ] = temp;
}
}
}
JDK帮助文档的使用
Math类生成随机数功能的简单了解
class Math_Random {
public static void main ( String[ ] args) {
for ( int i = 0 ; i < 10 ; i++ ) {
System. out. println ( Math. random ( ) ) ;
}
for ( int i = 0 ; i < 10 ; i++ ) {
System. out. println ( ( int ) ( Math. random ( ) * 100 ) + 1 ) ;
}
}
}
案例演示
import java. util. Scanner;
class Test_GuessNum {
public static void main ( String[ ] args) {
Scanner sc = new Scanner ( System. in) ;
System. out. println ( "请输入一个1-100的整数" ) ;
int guessNum = ( int ) ( Math. random ( ) * 100 ) + 1 ;
while ( true ) {
int result = sc. nextInt ( ) ;
if ( result > guessNum) {
System. out. println ( "大了" ) ;
} else if ( result < guessNum) {
System. out. println ( "小了" ) ;
} else {
System. out. println ( "中了" ) ;
break ;
}
}
}
}