Java基础学习Day08

「爱情、让人受尽委屈。」 2021-11-02 00:48 340阅读 0赞

#### 知识点 ####

1.  抽象类
2.  接口

##### 抽象类 #####

如何使用抽象类？  
抽象类用abstract修饰，抽象类中一旦有抽象方法，子类必须全部重写，否则也定义为抽象类  
注意事项：

1.  抽象类不能实例化对象
2.  抽象方法声明时不能加方法体
3.  abstra不能与final共存

##### 抽象类练习 #####

具体事物：基础班学员，就业班学员  
共性：姓名，学习，休假。  
code

public abstract class Student {
    	private String name;
    	
    	public String getName() {
    		return name;
    	}
    	
    	public void setName(String name) {
    		this.name = name;
    	}
    	
    	public abstract void study();
    	
    	public abstract void vacation();
    }

package com.day08;
    
    public class BasicClassStudent extends Student{
        
    	@Override
    	public void study() {
        
    		System.out.println("基础班学生学习");
    	}
    
    	@Override
    	public void vacation() {
        
    		System.out.println("基础班学生放假");
    	}
    }

package com.day08;
    
    public class EmploymentClassStudent extends Student{
        
    	@Override
    	public void study() {
        
    		System.out.println("就业班学生学习");
    	}
    
    	@Override
    	public void vacation() {
        
    		System.out.println("就业班学生放假");
    	}
    }

package com.day08;
    
    public class StudentTest {
        
    	public static void main(String[] args) {
        
    		BasicClassStudent student1 = new BasicClassStudent();
    		EmploymentClassStudent student2 = new EmploymentClassStudent();
    		
    		student1.setName("小明");
    		System.out.println(student1.getName());
    		student1.study();
    		student1.vacation();
    		
    		student1.setName("小红");
    		System.out.println(student1.getName());
    		student2.study();
    		student2.vacation();
    	}
    }

##### 接口 #####

接口(interface)名首字母要加一个I  
实现接口的类末尾要加Impl  
接口中默认属性：public static final  
接口中默认方法：public abstract  
实现接口的类要实现接口中所有的方法用implements  
类既可以继承一个的的同时实现多个接口  
如：`public class StudentImpl extends Student implements IStudent`

##### 接口练习 #####

具体事物：基础班学员，就业班学员  
共性：姓名，学习，休假。  
code

package com.day08;
    
    public interface IStudent {
        
    	public abstract void name();
    	public abstract void study();
    	public abstract void vacation();
    }

package com.day08;
    
    public class BasicClassStudentImpl implements IStudent{
        
    	@Override
    	public void name() {
        
    		System.out.println("基础班学生小明");
    	}
    	
    	@Override
    	public void study() {
        
    		System.out.println("基础班学生学习");
    	}
    
    	@Override
    	public void vacation() {
        
    		System.out.println("基础班学生放假");
    	}
    }

package com.day08;
    
    public class EmploymentClassStudentImpl implements IStudent{
        
    	@Override
    	public void name() {
        
    		System.out.println("就业班学生小红");
    	}
    	
    	@Override
    	public void study() {
        
    		System.out.println("就业班学生学习");
    	}
    
    	@Override
    	public void vacation() {
        
    		System.out.println("就业班学生放假");
    	}
    }

package com.day08;
    
    public class IStudentTest {
        
    	public static void main(String[] args) {
        	
    		BasicClassStudentImpl student01 = new BasicClassStudentImpl();
    		EmploymentClassStudentImpl student02 = new EmploymentClassStudentImpl();
    		
    		student01.name();
    		student01.study();
    		student01.vacation();
    		
    		student02.name();
    		student02.study();
    		student02.vacation();
    	}
    }

用接口实现一个登陆注册系统

package com.day08;
    
    public class User {
        
    	private int id;
    	private String name;
    	private String password;
    	private int age;
    	private String sex;
    	
    	public int getId() {
        
    		return id;
    	}
    	
    	public void setId(int id) {
        
    		this.id = id;
    	}
    	
    	public String getName() {
        
    		return name;
    	}
    	
    	public void setName(String name) {
        
    		this.name = name;
    	}
    	
    	public String getPassword() {
        
    		return password;
    	}
    	
    	public void setPassword(String password) {
        
    		this.password = password;
    	}
    	
    	public int getAge() {
        
    		return age;
    	}
    	
    	public void setAge(int age) {
        
    		this.age = age;
    	}
    	
    	public String getSex() {
        
    		return sex;
    	}
    	
    	public void setSex(String sex) {
        
    		this.sex = sex;
    	}
    	
    	public void print() {
        
    		System.out.printf("ID:%d\tName:%s\tPassword:%s\tAge:%d\tSex:%s\n",
    				id, name, password, age, sex);
    	}
    }

package com.day08;
    
    public interface IFuncation {
        
    	public abstract void add();
    	public abstract void delete();
    	public abstract void revise();
    	public abstract void query();
    }

package com.day08;
    
    import java.util.Scanner;
    
    public class FuncationImpl implements IFuncation{
        
    	private int count = 1;
    	private Scanner sca = new Scanner(System.in);
    	public static User[] user = new User[5];
    
    	@Override
    	public void add() {
        	
    		if(count > 10) {
        
    			System.out.println("用户已满，禁止添加0-0");
    			return ;
    		}
    		User temp = new User();
    		System.out.print("请输入添加的用户名：");
    		temp.setName(sca.next());
    		System.out.print("请设置该用户的密码：");
    		temp.setPassword(sca.next());
    		System.out.print("请设置该用户的年龄：");
    		temp.setAge(sca.nextInt());
    		System.out.print("请设置该用户的性别：");
    		temp.setSex(sca.next());
    		count++;
    		temp.setId(count);
    		user[count - 1] = temp;
    		System.out.println("添加成功0-0");
    		return ;
    	}
    
    	@Override
    	public void delete() {
        
    		if(count < 1) {
        
    			System.out.println("用户不可再删，删除失败0-0");
    			return ;
    		}
    		System.out.print("请输入要删除的编号：");
    		int id = sca.nextInt();
    		for(int i = 0; i < count; i++) {
        
    			if(id == user[i].getId()) {
        
    				for(int j = i; j < count - 1; j++) {
        
    					user[j] = user[j + 1];
    					user[j].setId(user[j].getId() - 1);
    				}
    				count--;
    				System.out.println("删除成功0-0");
    				return ;
    			}
    		}
    		System.out.println("查找不到所输入的编号0-0");
    		return ;
    	}
    
    	@Override
    	public void revise() {
        
    		System.out.print("请输入您索要修改的编号：");
    		int id = sca.nextInt();
    		for(int i = 0; i < count; i++) {
        
    			if(id == user[i].getId()) {
        
    				System.out.println("请修改以下数据：");
    				System.out.print("Name:");
    				user[i].setName(sca.next());
    				System.out.print("Age:");
    				user[i].setAge(sca.nextInt());
    				System.out.print("Sex:");
    				user[i].setSex(sca.next());
    				System.out.println("修改成功0-0");
    				return ;
    			}
    		}
    		System.out.println("查找不到所输入的编号0-0");
    		return ;
    	}
    
    	@Override
    	public void query() {
        
    		for(int i = 0; i < count; i++) {
        
    			user[i].print();			
    		}
    	}
    	
    	
    }

package com.day08;
    
    import java.util.Scanner;
    
    public class LemonSystem {
        
    	private static int n;
    	private static Scanner sca = new Scanner(System.in);
    	public static void main(String[] args) {
        
    		FuncationImpl funcationImpl = new FuncationImpl();
    		while(true) {
        
    			System.out.println("欢迎来到小柠檬系统0-0");
    			System.out.println("1. 登陆");
    			System.out.println("2. 注册");
    			System.out.println("0. 退出");
    			n = sca.nextInt();
    			if(n == 1) {
        
    				login(funcationImpl);
    			}
    			if(n == 2) {
        
    				register(funcationImpl);
    			}
    			if(n == 0) {
        
    				return ;
    			}			
    		}
    	}
    	
    	public static void register(FuncationImpl funcationImpl) {
        
    		User temp = new User();
    		System.out.print("请输入用户名：");
    		temp.setName(sca.next());
    		System.out.print("请设置该用户的密码：");
    		temp.setPassword(sca.next());
    		System.out.print("请设置该用户的年龄：");
    		temp.setAge(sca.nextInt());
    		System.out.print("请设置该用户的性别：");
    		temp.setSex(sca.next());
    		temp.setId(1);
    		FuncationImpl.user[0] = temp;
    		System.out.println("注册成功0-0");
    		return ;
    	}
    	
    	public static void login(FuncationImpl funcationImpl) {
        
    		System.out.print("请输入用户名：");
    		String name = sca.next();
    		System.out.print("请输入密码：");
    		String password = sca.next();
    		if(funcationImpl.user[0].getName().equals(name) && 
    				funcationImpl.user[0].getPassword().equals(password)) {
        
    			System.out.println("登陆成功0-0");
    			while(true) {
        
    				System.out.println("欢迎进入小柠檬内部系统0-0");
    				System.out.println("1. 添加");
    				System.out.println("2. 删除");
    				System.out.println("3. 修改");
    				System.out.println("4. 查询");
    				System.out.println("0. 退出");
    				n = sca.nextInt();
    				if(n == 1) {
        
    					funcationImpl.add();
    				}
    				if(n == 2) {
        
    					funcationImpl.delete();
    				}
    				if(n == 3) {
        
    					funcationImpl.revise();
    				}
    				if(n == 4) {
        
    					funcationImpl.query();
    				}
    				if(n == 0) {
        
    					break ;
    				}
    			}
    			return ;
    		}
    		System.out.println("登陆失败0-0");
    		return ;
    	}
    }