JAVA语言程序设计课后习题----第八单元解析（仅供参考）
2024-09-05 07:04:43
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+"\t"+"Integer的最小值"+integer.MIN_VALUE);
Long l=null;
System.out.println("Long的最大值"+l.MAX_VALUE+"\t"+"Long的最小值"+l.MIN_VALUE);
Float f=null;
System.out.println("Float的最大值"+f.MAX_VALUE+"\t"+"Float的最小值"+f.MIN_VALUE);
Double d=null;
System.out.println("Double的最大值"+d.MAX_VALUE+"\t"+"Double的最小值"+d.MIN_VALUE);
Character character=null;
System.out.println(" Character的最大值"+character.MAX_VALUE+"\t"+" Character的最小值"+character.MIN_VALUE);
Byte b=null;
System.out.println(" Byte的最大值"+b.MAX_VALUE+"\t"+" Byte的最小值"+b.MIN_VALUE);
Short s=null;
System.out.println("Short的最大值"+s.MAX_VALUE+"\t"+" 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];
}
}
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