JAVA语言程序设计课后习题----第八单元解析（仅供参考）

1　　本题主要考的是方法的克隆，与c++里面的拷贝有点相似，具体看书本p147

import java.util.Objects;

public class Square implements Cloneable{
    private int length;

    public Square(int length) {
        this.length = length;
    }

    @Override
    public String toString() {
        return "Square[" +
                "length=" + length +
                ']';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Square square = (Square) o;
        return length == square.length;
    }

    @Override
    public int hashCode() {
        return Objects.hash(length);
    }

    public static void main(String[] args) throws CloneNotSupportedException{
        Square s1=new Square(100);
        Square  s2=(Square)s1.clone();
        System.out.println(s1==s2);
        System.out.println(s1.equals(s2));
        System.out.println(s2.toString());

    }
}

2　　本题水题，主要就是考数组，把产生的需求数存在数组里

public class Suiji {
    public static int a[]=new int[6];
    public static void main(String[] args) {
        Suiji s=new Suiji();
        System.out.println("随机产生1000个1-6的数");
        s.stc(6);

        for (int i = 1; i <=6 ; i++) {
            System.out.println(i+"的概率是"+(a[i-1]*1.0/1000)*100+"%");
        }
        System.out.println("****************************");
        System.out.println("随机产生1000个1-1000的数");
        for (int i = 0; i < a.length; i++) {
            a[i]=0;
        }
        s.stc(1000);
        for (int i = 1; i <=6 ; i++) {
            System.out.println(i+"的概率是"+(a[i-1]*1.0/1000)*100+"%");
        }

    }
    public void stc(int num){
        for (int i = 0; i <1000 ; i++) {
            switch ((int)(Math.random()*num+1)){
                case 1:a[0]++;
                    break;
                case 2:a[1]++;
                    break;
                case 3:a[2]++;
                    break;
                case 4:a[3]++;
                    break;
                case 5:a[4]++;
                    break;
                case 6:a[5]++;
                    break;
            }
        }
    }
}

3　　本题注意sinx x是弧度即可

public class Area {
    public static void main(String[] args) {
        float a=4.0f,b=5.0f;

        float t= (float) Math.sin(30*(Math.PI/180));
       // System.out.println("三角形的面积为:"+(1*1.0/2)*a*b*t);
        System.out.println(((1*1.0/2)*a*b*t));
    }

}

4　　本题只要记得如何求最大值、最小值的封装方法即可（MAX_VALUE、MIN_VALUE）

public class Baozhuang {
    //    Integer integer;
    public static void main(String[] args) {
        Integer integer = null;
        System.out.println("Integer的最大值"+integer.MAX_VALUE+"	"+"Integer的最小值"+integer.MIN_VALUE);
        Long l=null;
        System.out.println("Long的最大值"+l.MAX_VALUE+"	"+"Long的最小值"+l.MIN_VALUE);
        Float f=null;
        System.out.println("Float的最大值"+f.MAX_VALUE+"	"+"Float的最小值"+f.MIN_VALUE);
        Double d=null;
        System.out.println("Double的最大值"+d.MAX_VALUE+"	"+"Double的最小值"+d.MIN_VALUE);
        Character character=null;
        System.out.println(" Character的最大值"+character.MAX_VALUE+"	"+" Character的最小值"+character.MIN_VALUE);
        Byte b=null;
        System.out.println(" Byte的最大值"+b.MAX_VALUE+"	"+" Byte的最小值"+b.MIN_VALUE);
        Short s=null;
        System.out.println("Short的最大值"+s.MAX_VALUE+"	"+" Short的最小值"+s.MIN_VALUE);

    }
}

5　　本题自行百度查看

6　　本题水题，plusDays就是给当前对象增加几天

import java.text.ParseException;
import java.time.LocalDate;
public class ch06 {
    public static void main(String[] args) throws ParseException {
        LocalDate pday=LocalDate.of(2017,1,1).plusDays(256);
        System.out.println(pday);
    }
}

7　　本题主要就是知道如何求天数，对什么值求模

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class ch07 {
    public static void main(String[] args) throws ParseException {
        Scanner input =new Scanner(System.in);
        String dbtime1 = input.next();  //第二个日期
        String dbtime2 = input.next();  //第一个日期
//算两个日期间隔多少天
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Date date1 = format.parse(dbtime1);
        Date date2 = format.parse(dbtime2);

        int a = (int) ((date1.getTime() - date2.getTime()) / (1000*3600*24));
        System.out.println(a);
    }
}

8　　本题具体自行查看书本p159

import java.time.LocalDate;
import java.time.format.TextStyle;
import java.util.Locale;
import java.util.Scanner;

public class PromtCalendar {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("输入一个年份(如2018)：");
        int year = input.nextInt();

        for (int j = 1; j <=12; j++) {
            //        返回本月第一天
            LocalDate dates = LocalDate.of(year,j, 1);
            String monthName = dates.getMonth().getDisplayName(TextStyle.FULL, Locale.getDefault());
//        返回当月的天数
            int dayOFmonth = dates.lengthOfMonth();
            System.out.println(year + "年     " + monthName);
            System.out.println("-------------------------------");
            System.out.printf("%4s%3s%3s%3s%3s%3s%3s%n", "一", "二", "三", "四", "五", "六", "日");
            int dayOfWeek = dates.getDayOfWeek().getValue();
            for (int i = 2; i <= dayOfWeek; i++) {
                System.out.printf("%4s", " ");
            }
            for (int i = 1; i <= dayOFmonth; i++) {
                System.out.printf("%4d", i);
                if ((dayOfWeek + i - 1) % 7 == 0)
                    System.out.println();
            }
            System.out.println();
        }
    }
}

9　　本题主要考的数组里面值的存入问题，也可以用if语句逐一进行判断，注意要月份和天数都要满足

import java.util.Scanner;

public class xingzuo {
   /* public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("输入一个年份(如2018)：");
int year=input.nextInt();
        int month = input.nextInt();
//       输入天数
        int day = input.nextInt();
        LocalDate dates3 = LocalDate.of(year, month, day).plusDays(30);
        //dates3.plusDays(30);
        System.out.println(dates3);

        LocalDate[] desk = {LocalDate.of( 0,3, 20), LocalDate.of(0, 4, 20),
                LocalDate.of(0, 4, 19), LocalDate.of(0, 4, 21),
                LocalDate.of(0, 5, 20), LocalDate.of(0, 6, 22),
                LocalDate.of(0, 6, 21), LocalDate.of(0, 7, 23),
                LocalDate.of(0, 7, 22), LocalDate.of(0, 8, 23),
                LocalDate.of(0, 8, 22), LocalDate.of(0, 9, 24),
                LocalDate.of(0, 9, 22), LocalDate.of(0, 10, 24),
                LocalDate.of(0, 10, 23), LocalDate.of(0, 11, 23),
                LocalDate.of(0, 11, 22), LocalDate.of(0, 12, 22),
                LocalDate.of(0, 12, 21), LocalDate.of(0, 1, 20),
                LocalDate.of(0, 1, 19), LocalDate.of(0, 2, 19),
                LocalDate.of(0, 2, 18), LocalDate.of(0, 3, 21)};


        if (dates3.isAfter(desk[0]) && dates3.isBefore(desk[1])) {

            System.out.println("白羊座" );
        }
        else if (dates3.isAfter(desk[2]) && dates3.isBefore(desk[3])){
            System.out.println("金牛座");
        }
        else if (dates3.isAfter(desk[4]) && dates3.isBefore(desk[5])){
            System.out.println("双子");
        }
        else if (dates3.isAfter(desk[6]) && dates3.isBefore(desk[7])){
            System.out.println("巨蟹");
        }
        else if (dates3.isAfter(desk[8]) && dates3.isBefore(desk[9])){
            System.out.println("狮子");
        }
        else if (dates3.isAfter(desk[10]) && dates3.isBefore(desk[11])){
            System.out.println("处女");
        }
        else if (dates3.isAfter(desk[12]) && dates3.isBefore(desk[13])){
            System.out.println("天平");
        }
        else if (dates3.isAfter(desk[14]) && dates3.isBefore(desk[15])){
            System.out.println("天蝎");
        }
        else if (dates3.isAfter(desk[16]) && dates3.isBefore(desk[17])){
            System.out.println("射手");
        }
        else if (dates3.isAfter(desk[18]) && dates3.isBefore(desk[19])){
            System.out.println("摩羯");
        }
        else if (dates3.isAfter(desk[20]) && dates3.isBefore(desk[21])){
            System.out.println("水平");
        }
        else if (dates3.isAfter(desk[22]) && dates3.isBefore(desk[23])){
            System.out.println("双鱼");
        }
    }*/

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        System.out.println("请输入出生日期如（5 20）");
        System.out.println(
                getConstellation(input.nextInt(),input.nextInt())
        );
    }
    private final static int[] dayArr = new int[] { 20, 19, 21, 20, 21, 22, 23, 23, 23, 24, 23, 22 };
    private final static String[] constellationArr = new String[] { "摩羯座", "水瓶座", "双鱼座", "白羊座", "金牛座", "双子座", "巨蟹座", "狮子座", "处女座", "天秤座", "天蝎座", "射手座", "摩羯座" };
    public static String getConstellation(int month, int day) {
        return day < dayArr[month - 1] ? constellationArr[month - 1] : constellationArr[month];
    }
}