類和對象的基本概念

封裝

Private權限修飾符

this關鍵字

構造方法：

標準的javaBean類

插件PTG可以一鍵生成javabean標準類

成員變量和局部變量

練習：文字版格斗游戲

Role類

import java.util.Random;public class Role {private String name;private int blood;//空參public Role(){}//全參public Role(String name,int blood){this.name=name;this.blood=blood;}public String getName(){return name;}public void setName(String name){this.name=name;}public int getBlood(){return blood;}public void setblood(int blood){this.blood=blood;}public void attack(Role role){//方法的調用者去攻擊參數(shù),參數(shù)是對象，而不是一個name了Random rd=new Random();int hurt=rd.nextInt(20);//剩余血量int remainblood=role.getBlood()-hurt;remainblood=remainblood<0?0:remainblood;//剩余血量如果為負數(shù)了，就修改為0role.setblood(remainblood);//這里要修改一下，被揍的人的血量，其血量為當前所剩的血量System.out.println(this.name+"舉起拳頭打了"+role.name+"一下,造成了"+hurt+"點傷害，"+role.getName()+"還剩下"+remainblood+"點血");}}

test類

public class test {public static void main(String[] args) {Role role1 = new Role("喬峰", 100);Role role2 = new Role("鳩摩智", 100);while(true){role1.attack(role2);if(role2.getBlood()==0){System.out.println(role1.getName()+"K.O了"+role2.getName());break;}role2.attack(role1);if(role1.getBlood()==0){System.out.println(role2.getName()+"K.O了"+role1.getName());break;}}} }

文字版格斗游戲升級版（加招式，性別，樣貌）

Role類

import java.util.Random;public class Role {private String name;private int blood;private char gender;private String face;//長相是隨機的String[] boyface ={"風流俊雅", "氣宇軒昂","面目猙獰"};String[] girlface={"美輪美奐","沉魚落雁","相貌丑陋"};String[] attacks_desc={"%s使出了一招【背心釘】，轉到對方的身后，一掌向%s背心的靈臺穴拍去。","%s使出了一招【游空】，飛起身形子半空中變掌為抓鎖向%s。","%s大喝一聲，一招【劈裂墜地】，錘向%s雙腿",};String[] injureds_desc={"結果%s退了半步，毫發(fā)無傷","結果給%s造成了一處瘀傷",};//空參public Role(){}//全參public Role(String name,int blood,char gender){this.name=name;this.blood=blood;this.gender=gender;setFace(gender);//this.face=face;隨機長相，所以不是在創(chuàng)建對象的時候給的}public char getGender(){return gender;}public void setgender(){this.gender=gender;}public String getFace(){return face;}public void setFace(char gender){Random rd=new Random();if(gender =='男'){int index=rd.nextInt(boyface.length);this.face=boyface[index];}else if(gender=='女'){int index=rd.nextInt(girlface.length);this.face=girlface[index];}else{this.face="面目猙獰";}}public String getName(){return name;}public void setName(String name){this.name=name;}public int getBlood(){return blood;}public void setblood(int blood){this.blood=blood;}public void attack(Role role){//方法的調用者去攻擊參數(shù),參數(shù)是對象，而不是一個name了Random r=new Random();int index2=r.nextInt(attacks_desc.length);String kunfu=attacks_desc[index2];//輸出一個攻擊效果System.out.printf(kunfu,this.getName(),role.getName());//souf沒有換行效果System.out.println();int hurt=r.nextInt(20);//剩余血量int remainblood=role.getBlood()-hurt;remainblood=remainblood<0?0:remainblood;//剩余血量如果為負數(shù)了，就修改為0role.setblood(remainblood);//這里要修改一下，被揍的人的血量，其血量為當前所剩的血量//受傷效果的描述//血量>90 0索引描述if(remainblood>90){System.out.printf(injureds_desc[0],role.getName());//此處要有souf，其中%s表示占位，后面的參數(shù)表示填充進去}else{System.out.printf(injureds_desc[1],role.getName());}System.out.println();//System.out.println(this.name+"舉起拳頭打了"+role.name+"一下,造成了"+hurt+"點傷害，"+role.getName()+"還剩下"+remainblood+"點血");}public void showRoleinfo(){System.out.println("姓名為："+getName());System.out.println("血量為："+getBlood());System.out.println("性別為："+getGender());System.out.println("長相為："+getFace());}}

test類

public class test {public static void main(String[] args) {Role role1 = new Role("喬峰", 100, '男');Role role2 = new Role("鳩摩智", 100, '男');role1.showRoleinfo();role2.showRoleinfo();while(true){role1.attack(role2);if(role2.getBlood()==0){System.out.println(role1.getName()+"K.O了"+role2.getName());break;}role2.attack(role1);if(role1.getBlood()==0){System.out.println(role2.getName()+"K.O了"+role1.getName());break;}}} }

練習：對象數(shù)組1

Goods類

public class Goods {private String id;private String name;private int price;private int remain;public Goods(){}public Goods(String id,String name,int price,int remain){this.id=id;this.name=name;this.price=price;this.remain=remain;}public String getId(){return id;}public void setId(){this.id=id;}public String getName(){return name;}public void setName(){this.name=name;}public int getPrice(){return price;}public void setPrice(){this.price=price;}public int getRemain(){return remain;}public void setRemain(){this.remain=remain;}}

test類

public class test {public static void main(String[] args) {//創(chuàng)建一個對象數(shù)組Goods[] arr=new Goods[3];//創(chuàng)建三個商品對象Goods g1=new Goods("001","華為p40",2000,100);Goods g2=new Goods("002","保溫杯",100,50);Goods g3=new Goods("003","鼠標",200,20);//把商品添加到數(shù)組中arr[0]=g1;arr[1]=g2;arr[2]=g3;//遍歷for (int i = 0; i < arr.length; i++) {Goods goods=arr[i];//創(chuàng)建一個新對象用來接收對象數(shù)組中的對象System.out.println(goods.getId()+","+goods.getName()+","+goods.getPrice()+","+goods.getPrice());}} }

鍵盤錄入

第一套體系：
nextInt();接收整數(shù)
nextDouble();接收小數(shù)
next();接收字符串
//第一套體系的特點：遇到空格，回車就停止接收，這些符號后面的數(shù)據(jù)就不會被接收了

第二套體系：
nextLine();接收字符串
//可以接收空格，制表符，遇到回車才停止接收數(shù)據(jù)

//注意兩套鍵盤錄入體系最好不要混用，先以第一套體系為主

練習：對象數(shù)組2

Car類

public class Car {private String brand;private int price;private String color;public Car(){}public Car( String brand, int price, String color){this.brand=brand;this.price=price;this.color=color;}public String getBrand(){return brand;}public void setBrand(String brand){this.brand=brand;}public int getPrice(){return price;}public void setPrice(int price){//沒有返回值用void，set方法要傳參數(shù)this.price=price;}public String getColor(){return color;}public void setColor(String color){this.color=color;}}

test類

import java.util.Scanner;public class test {public static void main(String[] args) {Car[] arr=new Car[3];Scanner sc=new Scanner(System.in);for (int i = 0; i < arr.length; i++) {Car c=new Car();System.out.println("請輸入汽車品牌");String brand=sc.next();c.setBrand(brand);System.out.println("請輸入汽車的價格");int price=sc.nextInt();c.setPrice(price);System.out.println("請輸入汽車的顏色");String color=sc.next();c.setColor(color);arr[i]=c;}for (int i = 0; i < arr.length; i++) {System.out.println(arr[i].getBrand()+","+arr[i].getPrice()+","+arr[i].getColor());}} }

練習：對象數(shù)組3（求平均價格）

Phone類

package day2;public class test {public static void main(String[] args) {GirlFriend[] arr=new GirlFriend[4];GirlFriend g1=new GirlFriend("小芳",29,'女',"唱歌");GirlFriend g2=new GirlFriend("小菜",26,'女',"hipop");GirlFriend g3=new GirlFriend("圓圓",18,'女',"跳舞");GirlFriend g4=new GirlFriend("方方",23,'女',"踢足球");arr[0]=g1;arr[1]=g2;arr[2]=g3;arr[3]=g4;int sum=0;int average=0;for (int i = 0; i < arr.length; i++) {sum+=arr[i].getAge();}average=sum/arr.length;System.out.println("女朋友的平均年齡是"+average);int count=0;for (int i = 0; i < arr.length; i++) {if(arr[i].getAge()<average){arr[i].showInfo();count++;}}System.out.println("比平均年齡小的共有"+count+"個");}}

test類

public class test {public static void main(String[] args) {Phone[] arr=new Phone[3];//定義對象數(shù)組//創(chuàng)建手機對象Phone phone1=new Phone("小米",1999,"粉色");//實例化對象Phone phone2=new Phone("華為",4999,"白色");Phone phone3=new Phone("魅族",3999,"黑色");int sum=0;double average=0.0;//把手機對象添加到數(shù)組中arr[0]=phone1;arr[1]=phone2;arr[2]=phone3;for (int i = 0; i < arr.length; i++) {sum+=arr[i].getPrice();}average=sum*1.0/arr.length;System.out.println(average);} }

練習：對象數(shù)組4（定義女朋友對象）

GirlFriend類

package day2;public class GirlFriend {private String name;private int age;private char gender;private String hobby;public GirlFriend(){ }public GirlFriend(String name,int age,char gender,String hobby){this.name=name;this.age=age;this.gender=gender;this.hobby=hobby;}public String getName(){return name;}public void setName(String name){this.name=name;}public int getAge(){return age;}public void setAge(int age){this.age=age;}public char getGender(){return gender;}public void setGender(char gender){this.gender=gender;}public String getHobby(){return hobby;}public void setHobby(String hobby){this.hobby=hobby;}public void showInfo(){System.out.println(this.name+","+this.age+","+this.gender+","+this.hobby);}}

test類

package day2;public class test {public static void main(String[] args) {GirlFriend[] arr=new GirlFriend[4];GirlFriend g1=new GirlFriend("小芳",29,'女',"唱歌");GirlFriend g2=new GirlFriend("小菜",26,'女',"hipop");GirlFriend g3=new GirlFriend("圓圓",18,'女',"跳舞");GirlFriend g4=new GirlFriend("方方",23,'女',"踢足球");arr[0]=g1;arr[1]=g2;arr[2]=g3;arr[3]=g4;int sum=0;int average=0;for (int i = 0; i < arr.length; i++) {sum+=arr[i].getAge();}average=sum/arr.length;System.out.println("女朋友的平均年齡是"+average);int count=0;for (int i = 0; i < arr.length; i++) {if(arr[i].getAge()<average){arr[i].showInfo();count++;}}System.out.println("比平均年齡小的共有"+count+"個");}}

練習：對象數(shù)組5（學生信息管理）

Student類

package day2;public class Student {private String name;private int id;private int age;public Student(){}public Student(String name,int id,int age){this.name=name;this.id=id;this.age=age;}public String getName(){return name;}public void setName(String name){this.name=name;}public int getId(){return id;}public void setId(int id){this.id=id;}public int getAge(){return age;}public void setAge(int age){this.age=age;} }

Stutest類

package day2;import java.util.Scanner;public class Stutest {public static void main(String[] args) {Student[] arr=new Student[3];Student stu1=new Student("張三",202316,18);Student stu2=new Student("李四",202317,19);Student stu3=new Student("王五",202318,20);//將對象添加到數(shù)組當中arr[0]=stu1;arr[1]=stu2;arr[2]=stu3;//要添加的對象Student stu4=new Student("趙六",202319,35);//添加一個學生對象//數(shù)組已滿,需要創(chuàng)建新的數(shù)組，將老數(shù)組的元素添加到新數(shù)組中，數(shù)組長度為老數(shù)組+1//添加的時候要判斷學號的唯一性Student[] arr2=new Student[arr.length+1];if(!Repeat(arr,stu4)){if(getCount(arr)<arr.length){//數(shù)組中元素個數(shù)小于數(shù)組長度說明還有空位置arr[getCount(arr)]=stu4;Check(arr);}else{arr2=newArr(arr,stu4);Check(arr2);}}else{System.out.println("Id重復，請修改id后重新添加");}//通過id刪除學生信息Scanner sc=new Scanner(System.in);System.out.println();System.out.println("請輸入你想要學生年齡+1的ID");int num=sc.nextInt();if(index(num,arr2)>0){arr2[index(num,arr2)].setAge(arr2[index(num,arr2)].getAge()+1);}else{System.out.println("沒有找到");}Check(arr2);}//定義方法：按照指定id返回其數(shù)組下標public static int index(int idnum,Student[] Arr){for (int i = 0; i < Arr.length; i++) {if(Arr[i].getId()==idnum){return i;}}return -1;}//要判斷遍歷老數(shù)組還是新數(shù)組,代碼會重復，所以定義一個方法遍歷所有學生信息public static void Check(Student[] Arr){for (int i = 0; i < Arr.length; i++) {if(Arr[i]!=null){//不為空才打印System.out.println(Arr[i].getName()+","+Arr[i].getId()+","+Arr[i].getAge());}}}//定義方法：創(chuàng)建新的數(shù)組，并將老數(shù)組中的元素加到新數(shù)組中public static Student[] newArr(Student[] Arr,Student Stu4){Student[] Arr2=new Student[Arr.length+1];for (int i = 0; i < Arr.length; i++) {//將老數(shù)組的元素添加到新數(shù)組中Arr2[i]=Arr[i];}Arr2[Arr.length]=Stu4;return Arr2;}//定義方法獲得數(shù)組中元素的個數(shù)public static int getCount(Student[] arr){int count=0;for (int i = 0; i < arr.length; i++) {if(arr[i]!=null){count++;}}return count;}//判斷加的元素id是否重復public static Boolean Repeat(Student[] arr,Student Stu4){for (int i = 0; i < arr.length; i++) {//判斷id是否重復，不重復則添加if(arr[i]!=null) {//此處要加非空判斷if (arr[i].getId() == Stu4.getId()) {return true;}}}return false;} }

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