學習Java05

學習Java的第三天展示下成果:
1.一個簡單的判斷登陸正確與否的程序:

class LoginValidate{
	private String username;
	private String password;
	public LoginValidate(String username,String password){
	this.username=username;
	this.password=password;
	}
	public boolean IsValidate(){
	if("heyao".equals(this.username) && "123456".equals(this.password)){
			return true;
			}
			return false;
	}
}
class Operate{
	private String data[];
	public Operate(String data[])
	{this.data=data;
	this.Exit();}
	public void Exit(){
	if(this.data.length!=2){
	System.out.println("error parameter");
	System.exit(1);
	}
	}
	public String GetInfo(){
		if(new LoginValidate(this.data[0],this.data[1]).IsValidate()){
		return "Login success!";}
		return "Login failed!";
		}
	
}
public class Day {
         public static void main(String args[]) {
                System.out.println(new Operate(args).GetInfo());
                   }
         }

2.一個簡單的數據表以及對應的一個java類:

DROP TABLE car PURGE;
DROP TABLE member PURGE;
DROP SEQUENCE member_seq;
DROP SEQUENCE car_seq;
CREATE SEQUENCE member_seq;
CREATE SEQUENCE car_seq;
CREATE TABLE member(
	mid				NUMBER;
	name			VARCHAR2(20) 		NOT NULL;
	CONSTRAINT pk_mid PRIMARY KEY (mid)
	);
CREATE TABLE car(
	mid				NUMBER;
	title			VARCHAR2(50);
	color			VARCHAR2(10);
	CONSTRAINT pk_mid PRIMARY KEY (cid);
	CONSTRAINT fk_mid FOREIGN KEY (mid) REFERENCES member(mid) ON DELETE SET NULL;
	);
	//Java類: 熟悉2個類的關聯  以及類內部的關聯
	class Member{
	private int mid;
	private String name;
	private Car car;
	private Member child;
	public Member(int mid ,String name){
	this.mid =mid;
	this.name=name;
	}
	public void setCar(Car car){
	this.car = car;
	}
	public Car getCar(){
	return this.car;
	}
	public void setChild(Member child){
	this.child=child;
	}
	public Member getChild(Member child){
	return this.child;
	}
	public String getMemberInfo(){
	return "NO."+ this.mid+",NAME:"+this.name;
	}
}
class Car {
	private String title;
	private String color;
	private Member member;
	public Car(String title,String color){
	this.title=title;
	this.color=color;
	}
	public void setMember(Member member){
	this.member=member;
	}
	public Member getMember(){
	return this.member;
	}

	public String getCarInfo(){
	return "CARNAME:"+this.title+"COLOR"+this.color;

	}
}

public class Day {
         public static void main(String args[]) {
               Member mem = new Member(22,"Eric");
			   Member chd = new Member(6,"xiaohai");
			   Car car = new Car("BMW",",RED");
			   Car c =new Car("auto0","Black");
			   mem.setCar(car);
			   car.setMember(mem);
			   mem.setChild(chd);
			   chd.setCar(c);
			   c.setMember(chd);
			   System.out.println("Find child's Car:" + mem.getChild().getCar().getCarInfo());
			   System.out.println(mem.getMemberInfo());
			   System.out.println(mem.getCar().getCarInfo());
			   System.out.println(car.getMember().getMemberInfo());
			   
                   }
         }

3.一對多的一個關聯的聯繫------對象數組:

class Emp{
	private int empno;
	private String ename;
	private String job;
	private double sal;
	private double comm;
	private Dept dept;
	private Emp mgr;
	public Emp(){}
	public Emp(int empno,String ename,String job,double sal,double comm){
		this.empno=empno;
		this.ename=ename;
		this.job=job;
		this.sal=sal;
		this.comm=comm;
		}
		public void setDept(Dept dept){
		this.dept=dept;
		}
		public Dept getDept(){
		return this.dept;
		}
		public void setMgr(Emp mgr){
		this.mgr=mgr;
		}
		public Emp getMgr(){
		return this.mgr;
		}
		public String getEmpInfo(){
	
		return "NO."+ this.empno+", NAME:"+this.ename+", LOCATION:"+
		this.job+", Salary:"+this.sal+", Commission:"+this.comm;
		}
}
class Dept{
	private int deptno;
	private String dname;
	private String loc;
	private Emp emps[];
	public Dept(){}
	public Dept(int deptno,String dname,String loc){
	this.deptno=deptno;
	this.dname=dname;
	this.loc=loc;
	}
	public void setEmps(Emp emp[]){
	this.emps=emps;
	}
	public Emp[] getEmps(){
	return this.emps;
	}
	public String getDeptInfo(){
		return "DEPN0."+this.deptno+", DEPNAME:"+this.dname+",Loc"+ this.loc;
	
		}
}
public class Day {
         public static void main(String args[]) {
               //配置關係
			   Dept dept =new Dept(10,"ACOOUNTING","NEW YORK");
			   Emp empa =new Emp (1,"fdsafda","Clerk",888.0,0.0);
			   Emp empb =new Emp (2,"ewrqewreqw","Manager",8888.0,0.0);
			   Emp empc =new Emp (4,"vcxzvzvz","Presidnent",88899.0,0.0);
			   //設置僱員和領導的關係
			   empa.setMgr(empb);
			   empb.setMgr(empc);
			   //官員是屬於部門的
			   empa.setDept(dept);
			   empb.setDept(dept);
			   empc.setDept(dept);
			   //部門有多個僱員
			   dept.setEmps(new Emp[]{empa,empb,empc});
			   //取得關係
			   System.out.println(dept.getDeptInfo());
			   for (int x = 0; x < dept.getEmps().length; x ++){
					System.out.println(dept.getEmps()[0].getEmpInfo());
					}
                   }
         
}


	

最後一個for循環出現空指向錯誤 不知爲何.還望高手指點.