Java第二次Blog
前言：
第四次作业难度较大，题量大，三道题，难度依次递减，知识点涉及了复杂的正则表达式，聚合，继承。第五次作业难度中等，题量大，共5道题，难度依次递增，知识点涉及了字符串的处理，合并两个有序数组，三种排序，正则表达式，升级版聚合。第六次作业难度简单，题量中等，共6道题，难度依次递增，知识点涉及了简单的正则表达式，继承和多态，接口和多态。可以看出题目一次次深入，并有对重要知识点的训练。
题目集4（7-2）源码：
import java.util.Scanner;
class DateUtil {
Day day;
public DateUtil(){
}
public DateUtil(int d, int m, int y){
this.day = new Day(d,m,y);
}
public Day getDay() {
return day;
}
public void setDay(Day d) {
this.day = d;
}
public boolean checkInputValidity(){
if(this.getDay().getMonth().getYear().validate()&&this.getDay().getMonth().validate()&&day.validate())
return true;
return false;
}
public boolean compare1(DateUtil date){
if (date.getDay().getMonth().getYear().getValue()==this.getDay().getMonth().getYear().getValue()
&&date.getDay().getMonth().getValue()==this.getDay().getMonth().getValue()
&&date.getDay().getValue()<this.getDay().getValue())
return true;
else
return false;
}
public boolean equal(DateUtil date){
if(equalMonth(date)){
return false;
}
else
return true;
}
public boolean compareDates(DateUtil date){
if (compare1(date))
return false;
if (date.getDay().getMonth().getYear().getValue()<this.getDay().getMonth().getYear().getValue())
return false;
else if (date.getDay().getMonth().getYear().getValue()==this.getDay().getMonth().getYear().getValue()
&&date.getDay().getMonth().getValue()<this.getDay().getMonth().getValue())
return false;
return true;
}
public boolean equalDay(DateUtil date){
if (this.getDay().getValue()==date.getDay().getValue())
return true;
else
return false;
}
public boolean equalMonth(DateUtil date){
if(this.getDay().getMonth().getValue()==date.getDay().getMonth().getValue())
return true;
else
return false;
}
public boolean equalYear(DateUtil date){
if( this.getDay().getMonth().getYear().getValue()==date.getDay().getMonth().getYear().getValue())
return true;
else
return false;
}
public boolean equalTwoDates(DateUtil date){
if (equalDay(date) &&equalYear(date)&& equalMonth(date))
return true;
else
return false;
}
public boolean equals(DateUtil date){
if(equalDay(date)){
return false;
}
else
return true;
}
public String showDate(){
return this.getDay().getMonth().getYear().getValue()+"-"+this.getDay().getMonth().getValue()+"-"+this.getDay().getValue();
}
public int deom(DateUtil m) {
int n = 0;
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
for (int i = m.getDay().getMonth().getValue()+1; i <=12; i++) {
n=n+mon_maxnum[i-1];
}
n=n+mon_maxnum[m.getDay().getMonth().getValue()-1]-m.getDay().getValue();
if(m.getDay().getMonth().getYear().isLeapYear()&&m.getDay().getMonth().getValue()<=2)
n++;
return n;
}
public DateUtil getNextNDays(int n){
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
int year, month, day;
int s = deom(this);
if (s>n) {
year=this.getDay().getMonth().getYear().getValue();
int m = mon_maxnum[this.getDay().getMonth().getValue()-1];
if (this.getDay().getMonth().getYear().isLeapYear()&&this.getDay().getMonth().getValue()==2) {
m++;
}
m=m-this.getDay().getValue();
if (m>=n) {
month = this.getDay().getMonth().getValue();
day = n+this.getDay().getValue();
}
else{
n=n-m;
month = this.getDay().getMonth().getValue()+1;
int k = month;
while(n-mon_maxnum[k-1]>0&&k<=12){
n -= mon_maxnum[k-1];
month++;
k++;
}
day = n;
}
}
else {
n=n-s;
year = this.getDay().getMonth().getYear().getValue()+1;
int y = 365;
if (new Year(year).isLeapYear()) {
y++;
}
for(;n>y;){
n-=y;
year++;
y=365;
if (new Year(year).isLeapYear())
y++;
}
int k = 1;
while(n-mon_maxnum[k-1]>0&&k<=12){
n =n- mon_maxnum[k-1];
k++;
}
month = k;
day = n;
}
return new DateUtil(year,month,day);
}
public DateUtil getPreviousNDays(int n) {
int year, month, day;
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
int d = 365 - deom(this);
if (this.getDay().getMonth().getYear().isLeapYear()) {
d++;
}
if (d> n) {
int i=0;
if(i!=0){
i++;
}
year = this.getDay().getMonth().getYear().getValue();
int s = this.getDay().getValue();
if (s > n) {
month = this.getDay().getMonth().getValue();
day = s- n;
} else {
n = n-s;
month = this.getDay().getMonth().getValue() - 1;
if (month == 0) {
month = 12;
year = this.getDay().getMonth().getYear().getValue() - 1;
}
int k = month;
while (n - mon_maxnum[k-1] > 0 && k >= 0) {
n =n- mon_maxnum[k-1];
month--;
k--;
}
day = mon_maxnum[k-1] - n;
if (new Year(year).isLeapYear() && month == 2) {
day++;
}
}
} else {
n =n- d;
year = this.getDay().getMonth().getYear().getValue() - 1;
int y = 365;
if (new Year(year).isLeapYear()) {
y++;
}
for(;n>y;){
n =n- y;
year--;
y = 365;
if (new Year(year).isLeapYear())
y++;
}
int k = 12;
while (n - mon_maxnum[k-1] > 0 && k >= 0) {
n =n- mon_maxnum[k-1];
k--;
}
month = k;
day =mon_maxnum[k-1] - n;
if (new Year(year).isLeapYear() && month == 2) {
day++;
}
}
return new DateUtil(year, month, day);
}
public int getDaysofDates(DateUtil date){
DateUtil a = this;
DateUtil b = date;
if (this.equalTwoDates(date)) {
return 0;
}
else if (!this.compareDates(date)) {
a = date;
b = this;
}
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
int m,n,d = 0;
for(m=a.getDay().getMonth().getYear().getValue()+1;m<b.getDay().getMonth().getYear().getValue();m++) {
d=d+365;
if(new Year(m).isLeapYear())
d++;
}
if (a.getDay().getMonth().getYear().getValue()!=b.getDay().getMonth().getYear().getValue()) {
for(n=1;n<b.getDay().getMonth().getValue();n++)
d+=mon_maxnum[n-1];
for(n=a.getDay().getMonth().getValue()+1;n<=12;n++)
d=d+mon_maxnum[n-1];
d+=mon_maxnum[a.getDay().getMonth().getValue()-1]-a.getDay().getValue();
d+=b.getDay().getValue();
if(a.getDay().getMonth().getYear().isLeapYear()&&a.getDay().getMonth().getValue()<=2)
d++;
if (b.getDay().getMonth().getYear().isLeapYear()&&b.getDay().getMonth().getValue()>2) {
d++;
}
}
else if(a.getDay().getMonth().getYear().getValue()==b.getDay().getMonth().getYear().getValue()&&a.getDay().getMonth().getValue()!=b.getDay().getMonth().getValue()){
for(n=a.getDay().getMonth().getValue()+1;n<=b.getDay().getMonth().getValue()-1;n++)
d+=mon_maxnum[n-1];
d+=mon_maxnum[a.getDay().getMonth().getValue()-1]-a.getDay().getValue();
d+=b.getDay().getValue();
if(a.getDay().getMonth().getYear().isLeapYear()&&a.getDay().getMonth().getValue()<=2)
d++;
}
else if(a.getDay().getMonth().getYear().getValue()==b.getDay().getMonth().getYear().getValue()&&a.getDay().getMonth().getValue()==b.getDay().getMonth().getValue()){
d=b.getDay().getValue()-a.getDay().getValue();
}
return d;
}
}
class Year{
int value;
public Year() {
}
public Year(int value) {
this.value = value;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public boolean isLeapYear(){
if (((value % 4 == 0) && (value % 100 != 0)) || (value % 400 == 0))
return true;
else
return false;
}
public boolean validate() {
if(value>2050||value<1900)
return false;
else
return true;
}
public void yearIncrement() {
value++;
}
public void yearReduction() {
value--;
}
}
class Month{
int value;
Year year;
public Month() {
}
public Month(int yearValue,int monthValue) {
this.year = new Year(yearValue);
this.value = monthValue;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public Year getYear() {
return year;
}
public void setYear(Year year) {
this.year = year;
}
public void resetMin() {
value=1;
}
public void resetMax() {
value=12;
}
public boolean validate() {
if(value>12||value<1)
return false;
else
return true;
}
public void monthIncrement() {
value++;
}
public void monthReduction() {
value--;
}
}
class Day{
int value;
Month month;
int mon_maxnum[]= {31,28,31,30,31,30,31,31,30,31,30,31};
public Day() {
}
public Day(int yearValue,int monthValue,int dayValue) {
this.value = dayValue;
this.month = new Month(yearValue,monthValue);
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public Month getMonth() {
return month;
}
public void setMonth(Month value) {
this.month = value;
}
public void resetMin() {
value=1;
}
public void resetMax() {
value=mon_maxnum[month.getValue()-1];
}
public boolean validate() {
if(this.getMonth().getYear().isLeapYear())
mon_maxnum[1]=29;
if(value>mon_maxnum[ month.getValue()-1]||value<1)
return false;
else
return true;
}
public void dayIncrement() {
value++;
}
public void dayReduction() {
value--;
}
}
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int year,month,day;
int num= input.nextInt();
if (num == 1) {
int m = 0;
year = Integer.parseInt(input.next());
month = Integer.parseInt(input.next());
day = Integer.parseInt(input.next());
DateUtil date = new DateUtil(year, month, day);
if (date.checkInputValidity()==false) {
System.out.println("Wrong Format");
System.exit(0);
}
m = input.nextInt();
if (m < 0) {
System.out.println("Wrong Format");
System.exit(0);
}
System.out.println(date.getNextNDays(m).showDate());
} else if (num == 2) {
int n = 0;
year = Integer.parseInt(input.next());
month = Integer.parseInt(input.next());
day = Integer.parseInt(input.next());
DateUtil date = new DateUtil(year, month, day);
if (date.checkInputValidity()==false) {
System.out.println("Wrong Format");
System.exit(0);
}
n = input.nextInt();
if (n < 0) {
System.out.println("Wrong Format");
System.exit(0);
}
System.out.println(date.getPreviousNDays(n).showDate());
} else if (num == 3) {
int y= Integer.parseInt(input.next());
int m = Integer.parseInt(input.next());
int d = Integer.parseInt(input.next());
year = Integer.parseInt(input.next());
month = Integer.parseInt(input.next());
day = Integer.parseInt(input.next());
DateUtil f = new DateUtil(year, month, day);
DateUtil t = new DateUtil(y, m,d);
if (f.checkInputValidity() && t.checkInputValidity()) {
System.out.println(f.getDaysofDates(t));
} else {
System.out.println("Wrong Format");
System.exit(0);
}
} else {
System.out.println("Wrong Format");
System.exit(0);
}
}
}
报表：
类图：
踩坑心得：刚开始看不懂类中传入的参数，后来才明白这样做可以才可以让本类做好自己的工作，日期的算法不止一种，第一种一天一天算可能会超时，我改进后的代码就提高效率。
改进建议：改进日期的常规算法，避免一天一天进行计算。
题目集5（7-5）源码：
import java.util.Scanner;
class DateUtil {
Day day;
public DateUtil(){
}
public DateUtil(int d, int m, int y){
this.day = new Day(d,m,y);
}
public Day getDay() {
return day;
}
public void setDay(Day d) {
this.day = d;
}
public boolean checkInputValidity(){
if(this.getDay().getMonth().getYear().validate()&&this.getDay().getMonth().validate()&&day.validate())
return true;
return false;
}
public boolean compare1(DateUtil date){
if (date.getDay().getMonth().getYear().getValue()==this.getDay().getMonth().getYear().getValue()
&&date.getDay().getMonth().getValue()==this.getDay().getMonth().getValue()
&&date.getDay().getValue()<this.getDay().getValue())
return true;
else
return false;
}
public boolean equal(DateUtil date){
if(equalMonth(date)){
return false;
}
else
return true;
}
public boolean compareDates(DateUtil date){
if (compare1(date))
return false;
if (date.getDay().getMonth().getYear().getValue()<this.getDay().getMonth().getYear().getValue())
return false;
else if (date.getDay().getMonth().getYear().getValue()==this.getDay().getMonth().getYear().getValue()
&&date.getDay().getMonth().getValue()<this.getDay().getMonth().getValue())
return false;
return true;
}
public boolean equalDay(DateUtil date){
if (this.getDay().getValue()==date.getDay().getValue())
return true;
else
return false;
}
public boolean equalMonth(DateUtil date){
if(this.getDay().getMonth().getValue()==date.getDay().getMonth().getValue())
return true;
else
return false;
}
public boolean equalYear(DateUtil date){
if( this.getDay().getMonth().getYear().getValue()==date.getDay().getMonth().getYear().getValue())
return true;
else
return false;
}
public boolean equalTwoDates(DateUtil date){
if (equalDay(date) &&equalYear(date)&& equalMonth(date))
return true;
else
return false;
}
public boolean equals(DateUtil date){
if(equalDay(date)){
return false;
}
else
return true;
}
public String showDate(){
return this.getDay().getMonth().getYear().getValue()+"-"+this.getDay().getMonth().getValue()+"-"+this.getDay().getValue();
}
public int deom(DateUtil m) {
int n = 0;
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
for (int i = m.getDay().getMonth().getValue()+1; i <=12; i++) {
n=n+mon_maxnum[i-1];
}
n=n+mon_maxnum[m.getDay().getMonth().getValue()-1]-m.getDay().getValue();
if(m.getDay().getMonth().getYear().isLeapYear()&&m.getDay().getMonth().getValue()<=2)
n++;
return n;
}
public DateUtil getNextNDays(int n){
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
int year, month, day;
int s = deom(this);
if (s>n) {
year=this.getDay().getMonth().getYear().getValue();
int m = mon_maxnum[this.getDay().getMonth().getValue()-1];
if (this.getDay().getMonth().getYear().isLeapYear()&&this.getDay().getMonth().getValue()==2) {
m++;
}
m=m-this.getDay().getValue();
if (m>=n) {
month = this.getDay().getMonth().getValue();
day = n+this.getDay().getValue();
}
else{
n=n-m;
month = this.getDay().getMonth().getValue()+1;
int k = month;
while(n-mon_maxnum[k-1]>0&&k<=12){
n -= mon_maxnum[k-1];
month++;
k++;
}
day = n;
}
}
else {
n=n-s;
year = this.getDay().getMonth().getYear().getValue()+1;
int y = 365;
if (new Year(year).isLeapYear()) {
y++;
}
for(;n>y;){
n-=y;
year++;
y=365;
if (new Year(year).isLeapYear())
y++;
}
int k = 1;
while(n-mon_maxnum[k-1]>0&&k<=12){
n =n- mon_maxnum[k-1];
k++;
}
month = k;
day = n;
}
return new DateUtil(year,month,day);
}
public DateUtil getPreviousNDays(int n) {
int year, month, day;
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
int d = 365 - deom(this);
if (this.getDay().getMonth().getYear().isLeapYear()) {
d++;
}
if (d> n) {
int i=0;
if(i!=0){
i++;
}
year = this.getDay().getMonth().getYear().getValue();
int s = this.getDay().getValue();
if (s > n) {
month = this.getDay().getMonth().getValue();
day = s- n;
} else {
n = n-s;
month = this.getDay().getMonth().getValue() - 1;
if (month == 0) {
month = 12;
year = this.getDay().getMonth().getYear().getValue() - 1;
}
int k = month;
while (n - mon_maxnum[k-1] > 0 && k >= 0) {
n =n- mon_maxnum[k-1];
month--;
k--;
}
day = mon_maxnum[k-1] - n;
if (new Year(year).isLeapYear() && month == 2) {
day++;
}
}
} else {
n =n- d;
year = this.getDay().getMonth().getYear().getValue() - 1;
int y = 365;
if (new Year(year).isLeapYear()) {
y++;
}
for(;n>y;){
n =n- y;
year--;
y = 365;
if (new Year(year).isLeapYear())
y++;
}
int k = 12;
while (n - mon_maxnum[k-1] > 0 && k >= 0) {
n =n- mon_maxnum[k-1];
k--;
}
month = k;
day =mon_maxnum[k-1] - n;
if (new Year(year).isLeapYear() && month == 2) {
day++;
}
}
return new DateUtil(year, month, day);
}
public int getDaysofDates(DateUtil date){
DateUtil a = this;
DateUtil b = date;
if (this.equalTwoDates(date)) {
return 0;
}
else if (!this.compareDates(date)) {
a = date;
b = this;
}
int []mon_maxnum={31,28,31,30,31,30,31,31,30,31,30,31};
int m,n,d = 0;
for(m=a.getDay().getMonth().getYear().getValue()+1;m<b.getDay().getMonth().getYear().getValue();m++) {
d=d+365;
if(new Year(m).isLeapYear())
d++;
}
if (a.getDay().getMonth().getYear().getValue()!=b.getDay().getMonth().getYear().getValue()) {
for(n=1;n<b.getDay().getMonth().getValue();n++)
d+=mon_maxnum[n-1];
for(n=a.getDay().getMonth().getValue()+1;n<=12;n++)
d=d+mon_maxnum[n-1];
d+=mon_maxnum[a.getDay().getMonth().getValue()-1]-a.getDay().getValue();
d+=b.getDay().getValue();
if(a.getDay().getMonth().getYear().isLeapYear()&&a.getDay().getMonth().getValue()<=2)
d++;
if (b.getDay().getMonth().getYear().isLeapYear()&&b.getDay().getMonth().getValue()>2) {
d++;
}
}
else if(a.getDay().getMonth().getYear().getValue()==b.getDay().getMonth().getYear().getValue()&&a.getDay().getMonth().getValue()!=b.getDay().getMonth().getValue()){
for(n=a.getDay().getMonth().getValue()+1;n<=b.getDay().getMonth().getValue()-1;n++)
d+=mon_maxnum[n-1];
d+=mon_maxnum[a.getDay().getMonth().getValue()-1]-a.getDay().getValue();
d+=b.getDay().getValue();
if(a.getDay().getMonth().getYear().isLeapYear()&&a.getDay().getMonth().getValue()<=2)
d++;
}
else if(a.getDay().getMonth().getYear().getValue()==b.getDay().getMonth().getYear().getValue()&&a.getDay().getMonth().getValue()==b.getDay().getMonth().getValue()){
d=b.getDay().getValue()-a.getDay().getValue();
}
return d;
}
}
class Year{
int value;
public Year() {
}
public Year(int value) {
this.value = value;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public boolean isLeapYear(){
if (((value % 4 == 0) && (value % 100 != 0)) || (value % 400 == 0))
return true;
else
return false;
}
public boolean validate() {
if(value>2020||value<1820)
return false;
else
return true;
}
public void yearIncrement() {
value++;
}
public void yearReduction() {
value--;
}
}
class Month{
int value;
Year year;
public Month() {
}
public Month(int yearValue,int monthValue) {
this.year = new Year(yearValue);
this.value = monthValue;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public Year getYear() {
return year;
}
public void setYear(Year year) {
this.year = year;
}
public void resetMin() {
value=1;
}
public void resetMax() {
value=12;
}
public boolean validate() {
if(value>12||value<1)
return false;
else
return true;
}
public void monthIncrement() {
value++;
}
public void monthReduction() {
value--;
}
}
class Day{
int value;
Month month;
int mon_maxnum[]= {31,28,31,30,31,30,31,31,30,31,30,31};
public Day() {
}
public Day(int yearValue,int monthValue,int dayValue) {
this.value = dayValue;
this.month = new Month(yearValue,monthValue);
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public Month getMonth() {
return month;
}
public void setMonth(Month value) {
this.month = value;
}
public void resetMin() {
value=1;
}
public void resetMax() {
value=mon_maxnum[month.getValue()-1];
}
public boolean validate() {
if(this.getMonth().getYear().isLeapYear())
mon_maxnum[1]=29;
if(value>mon_maxnum[ month.getValue()-1]||value<1)
return false;
else
return true;
}
public void dayIncrement() {
value++;
}
public void dayReduction() {
value--;
}
}
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int year,month,day;
int num= input.nextInt();
if (num == 1) {
int m = 0;
year = Integer.parseInt(input.next());
month = Integer.parseInt(input.next());
day = Integer.parseInt(input.next());
DateUtil date = new DateUtil(year, month, day);
if (date.checkInputValidity()==false) {
System.out.println("Wrong Format");
System.exit(0);
}
m = input.nextInt();
if (m < 0) {
System.out.println("Wrong Format");
System.exit(0);
}
System.out.print(date.getDay().getMonth().getYear().value + "-" + date.getDay().getMonth().value + "-" + date.getDay().value + " next " + m + " days is:");
System.out.println(date.getNextNDays(m).showDate());
} else if (num == 2) {
int n = 0;
year = Integer.parseInt(input.next());
month = Integer.parseInt(input.next());
day = Integer.parseInt(input.next());
DateUtil date = new DateUtil(year, month, day);
if (date.checkInputValidity()==false) {
System.out.println("Wrong Format");
System.exit(0);
}
n = input.nextInt();
if (n < 0) {
System.out.println("Wrong Format");
System.exit(0);
}
System.out.print(date.getDay().getMonth().getYear().value + "-" + date.getDay().getMonth().value + "-" + date.getDay().value + " previous " + n + " days is:");
System.out.println(date.getPreviousNDays(n).showDate());
} else if (num == 3) {
int y= Integer.parseInt(input.next());
int m = Integer.parseInt(input.next());
int d = Integer.parseInt(input.next());
year = Integer.parseInt(input.next());
month = Integer.parseInt(input.next());
day = Integer.parseInt(input.next());
DateUtil f = new DateUtil(year, month, day);
DateUtil t = new DateUtil(y, m,d);
if (f.checkInputValidity() && t.checkInputValidity()) {
System.out.println("The days between " +t.showDate() + " and " + f.showDate() + " are:"
+ f.getDaysofDates(t));
} else {
System.out.println("Wrong Format");
System.exit(0);
}
} else {
System.out.println("Wrong Format");
System.exit(0);
}
}
}
报表：
类图：
踩坑心得：弄清输入格式谁是先输入的日期谁是后输入的日期。
改进建议：
日期算法的简化，做到不超时。
两种日期类聚合优劣比较：
第一种聚合优缺点：
它采用的是依次往下找的形式，如果我要达到某个地方，那我一定要经过之前的位置，这样的结构可以使程序的整体性更强，执行起来更加有章法。其缺点是如果类很多，那么程序依次往下走就会很费时间，代码很长，有时太过复杂容易出错。
第二中聚合优缺点：
它采用的是一个类控制其他所有类的聚合关系，每一个类各管个的，只需要一个类来调用他们并使用里面的属性。有一个明显的优点就是显得更加简洁，非常容易让人理解，缺点是类与类之间几乎无关联，所以在写代码就忘了这个类的作用。
题目集4（7-3）源代码：
import java.util.Scanner;
class Shape
{
public Shape()
{
System.out.println("Constructing Shape");
}
public double getArea()
{
return 0.0;
}
}
class Circle extends Shape
{
private double radius;
public Circle()
{
System.out.println("Constructing Circle");
}
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea() {
return Math.PI*radius*radius;
}
}
class Rectangle extends Shape
{
private double length;
private double width;
public Rectangle()
{
System.out.println("Constructing Rectangle");
}
public double getLength() {
return length;
}
public void setLength(double length) {
this.length = length;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
public double getArea() {
return 1.0*width*length;
}
}
class Ball extends Circle
{
public Ball()
{
System.out.println("Constructing Ball");
}
public double getArea() {
return 4.0*Math.PI*getRadius()*getRadius();
}
public double getVolume()
{
return 4.0/3.0*Math.PI*getRadius()*getRadius()*getRadius();
}
}
class Box extends Rectangle
{
private double height;
public Box()
{
System.out.println("Constructing Box");
}
public void setHeight(double height) {
this.height = height;
}
public double getHeight() {
return height;
}
public double getArea() {
return 2*(getWidth()*getLength()+getLength()*height+getWidth()*height);
}
public double getVolume()
{
return height*getLength()*getWidth();
}
}
public class Main {
public static void main(String[] args) {
int num;
Scanner scanner=new Scanner(System.in);
num=scanner.nextInt();
switch(num)
{
case 1:
double r=scanner.nextDouble();
if(r<0) {
System.out.println("Wrong Format");
}
else {
Circle circle=new Circle();
circle.setRadius(r);
System.out.printf("Circle's area:%.2f\n",circle.getArea());
}
break;
case 2:
double length=scanner.nextDouble();
double width=scanner.nextDouble();
if(width<0||length<0) {
System.out.println("Wrong Format");
}
else {
Rectangle rectangle=new Rectangle();
rectangle.setLength(length);
rectangle.setWidth(width);
System.out.printf("Rectangle's area:%.2f\n",rectangle.getArea());
}
break;
case 3:
double r2=scanner.nextDouble();
if(r2<0) {
System.out.println("Wrong Format");
}
else {
Ball ball=new Ball();
ball.setRadius(r2);
System.out.printf("Ball's surface area:%.2f\n",ball.getArea());
System.out.printf("Ball's volume:%.2f\n",ball.getVolume());
}
break;
case 4:
double width2=scanner.nextDouble();
double length2=scanner.nextDouble();
double height=scanner.nextDouble();
if(width2<0||length2<0||height<0) {
System.out.println("Wrong Format");
}
else {
Box box=new Box();
box.setHeight(height);
box.setWidth(width2);
box.setLength(length2);
System.out.printf("Box's surface area:%.2f\n",box.getArea());
System.out.printf("Box's volume:%.2f\n",box.getVolume());
}
break;
default:
System.out.println("Wrong Format");
}
}
}
报表：
类图：
踩坑心得：
继承关键字extends，数据类型是double,别忘了系数前面是乘以1.0。
改进建议：
利用好重写方法，简化代码。
题目集6（7-5）源码：
import java.util.Arrays;
import java.util.Scanner;
import static java.lang.System.exit;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int ci, tr, re;
ci= sc.nextInt();
re = sc.nextInt();
tr = sc.nextInt();
if (ci < 0 || tr < 0 || re < 0) {
System.out.println("Wrong Format");
exit(0);
}
Circle []a=new Circle[ci];
Rectangle []b=new Rectangle[re];
Triangle []c=new Triangle[tr];
double[] area=new double [ci+tr+re];
double sumArea=0;
int num=0;
for(int i=0;i<ci;i++){
double radius=sc.nextDouble();
a[i]=new Circle(radius);
area[num]=a[i].getArea();
num++;
if(a[i].validate()==false){
System.out.println("Wrong Format");
exit(0);
}
}
for(int i=0;i<re;i++){
double width=sc.nextDouble();
double length=sc.nextDouble();
b[i]=new Rectangle(width,length);
area[num]=b[i].getArea();
num++;
if(b[i].validate()==false){
System.out.println("Wrong Format");
exit(0);
}
}
for(int i=0;i<tr;i++){
double m=sc.nextDouble(),n=sc.nextDouble(),k=sc.nextDouble();
c[i]=new Triangle(m,n,k);
area[num]=c[i].getArea();
num++;
if(c[i].validate()==false){
System.out.println("Wrong Format");
exit(0);
}
}
System.out.println("Original area:");
for(int i=0;i<ci+tr+re;i++){
System.out.printf("%.2f ",area[i]);
sumArea+=area[i];
}
System.out.printf("\n");
System.out.printf("Sum of area:");
System.out.printf("%.2f\n",sumArea);
System.out.println("Sorted area:");
Arrays.sort(area);
for(int i=0;i<ci+tr+re;i++){
System.out.printf("%.2f ",area[i]);
}
System.out.printf("\n");
System.out.printf("Sum of area:%.2f",sumArea);
}
}
class Circle extends Shape{
private double radius;
public Circle(){
}
public Circle(double radius){
this.radius=radius;
}
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea() {
return Math.PI*radius*radius;
}
public boolean validate(){
if(radius<=0)
return false;
return true;
}
}
class Triangle extends Shape {
double side1,side2,side3;
public Triangle(double a, double b, double c) {
this.side1 = a;
this.side2 = b;
this.side3 = c;
}
public double getArea() {
double p = (side1 + side2 + side3) / 2;
return 1.0*Math.sqrt(p * (p - side1) * (p - side2) * (p - side3));
}
public boolean validate() {
if (side1 <= 0 || side2 <= 0 || side3 <=0) {
return false;
}
if(side1+side2>side3&&side1+side3>side2&&side3+side2>side1)
return true;
else
return false;
}
}
class Rectangle extends Shape{
private double length;
private double width;
public Rectangle()
{
}
public double getLength() {
return length;
}
public void setLength(double length) {
this.length = length;
}
public Rectangle(double width, double length) {
this.width=width;
this.length = length;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
public double getArea() {
return 1.0*width*length;
}
public boolean validate(){
if(width<=0||length<=0){
return false;
}
return true;
}
}
abstract class Shape {
public abstract boolean validate ();
public abstract double getArea();
}
报表：
类图：
踩坑心得：
应该注意到不能被显而易见的测试点，如创造0个矩形对象，三角形判断。
改进建议：
海伦公式求面积的应用，和调用Math.
题目集6（7-6）源码：
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
double s=sc.nextDouble();
double a=sc.nextDouble();
double b=sc.nextDouble();
GetArea i=new Circle(s);
GetArea j=new Rectangle(a,b);
if(s<=0){
System.out.println("Wrong Format");
}
else if(a<=0||b<=0) {
System.out.println("Wrong Format");
}
else{
System.out.printf("%.2f",i.getArea());
System.out.print("\n");
System.out.printf("%.2f",j.getArea());
}
}
}
class Circle implements GetArea{
private double radius;
public Circle(){
}
public Circle(double radius){
this.radius=radius;
}
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public double getArea() {
return Math.PI*radius*radius;
}
}
class Rectangle implements GetArea{
private double length;
private double width;
public Rectangle()
{
}
public double getLength() {
return length;
}
public void setLength(double length) {
this.length = length;
}
public Rectangle(double width, double length) {
this.width=width;
this.length = length;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
public double getArea() {
return 1.0*width*length;
}
}
interface GetArea {
public default double getArea(){
return 1.0;
}
}
报表：
类图：
踩坑心得：
接口关键字是 implements，在这个接口里面定义一个抽象方法，当这些类对这个接口进行调用后自行对这个接口进行重写，与正常的类一样。
改进建议：
对于可重写的东西可以是接口来表示。
三种渐进式图形设计的思路与技术运用：
题目集4（7-3）中circle类和rectangle类继承shape类，重写shape类的getArea()方法，ball类继承circle类，重写getArea()方法并定义求定义求体积方法。box类继承rectangle类的属性和getArea()方法，并定义新的属性height，重写父类的getArea()方法，并定义求立方体体积方法。各个子类封装自己的属性，属性无法被继承，只能重新定义。
题目集6（7-5）中circle类、rectangle类和triangle类继承同一个父类shape类，父类未定义属性，各个子类封装自己的属性，属性无法被继承，只能重新定义。
题目集6（7-6）中使用接口GetArea，定义方法getArea()，通过implements关键字实现接口，circle类和rectangle类重写getArea()方法。再circle类和rectangle类中定义它们自己的私有属性。
三次正则表达式的分析总结：
1、第一个正则表达式是水文数据，储存到固定的地址就显得十分复杂，我的写法是先将其按“|”分开再按“/”分开，每个数据两边匹配零个或多个空格，多次使用split对分好的字符串进行储存，实现算法，正则表达式如下：
String pi1=" *([1-9]\\d{0,3}/([1-9]|1[0-2])/([1-9]|1[0-2]|3[0-1])) (([02468]|1[02468]|2[02]):[0][0]) *";
String pi2=" *(([1-9]\\d{0,2}.[0-9]\\d{0,2})|([1-9]\\d{0,2})) *";
String pi3=" *([1-9].[0-9][0-9]) *";
String pi4=" *([1-9]\\d{0,1}.([0-9]\\d{0,2})|([1-9]\\d{0,2})) *";
2、第二个是关键字，需要匹配两种注释和字符串。
String pi1=("(.*)//(.*)"）；
String pi2=("\"(.*?)\"")；
String pi3=("/\\*(.*?)\\*/")；
3、第三个多种简单匹配
Pattern p=Pattern.compile("[^0]([0-9]{4,14})");
Pattern p=Pattern.compile("[a-z|A-Z|0-9]{4}");
Pattern p=Pattern.compile("2020(1[1234567]|61|7[123]|8[12])(([1-3][0-9])|40|01|02|03|04|05|06|07|08|09)");
题目集5（7-4）源码：
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
String str;
StringBuilder ss=new StringBuilder();
Map map=new HashMap();
String []key= { "abstract","assert","boolean","break","byte","case","catch",
"char","class","const","continue","default","do","double","else",
"enum","extends","false","final","finally","float",
"for","goto","if","implements","import","instanceof",
"int","interface","long","native","new","null","package",
"private","protected","public","return","short","static",
"strictfp","super","switch","synchronized","this","throw",
"throws","transient","true","try","void","volatile","while"
};
for(int i=0;;i++) {
str=input.nextLine();
if(str.equals("exit"))
break;
if(str.matches("(.*)//(.*)"))
{String a[]=str.split("//");
ss.append(a[0]+" ");
}
else
{ss.append(str+" ");
}
}
int l;
int j=0;
int num=0;
String s=ss.toString();
Pattern p=Pattern.compile("\"(.*?)\"");
Matcher m=p.matcher(s);
while(m.find()==true){
s=s.replace(m.group()," ");
m=p.matcher(s);
}
p=Pattern.compile("/\\*(.*?)\\*/");
m=p.matcher(s);
if(j>0){ j=0; }
while(m.find()==true){
s=s.replace(m.group()," ");
m=p.matcher(s);
}
p=Pattern.compile("\"(.*?)\"");//字符串中关键字
m=p.matcher(s);
while(m.find()==true)
{
s=s.replace(m.group()," ");
m=p.matcher(s);
}
panduan d=new panduan();
if(d.empty(s)==false)
{System.out.println("Wrong Format");
System.exit(0);
}
else
l=1;
s=s.replace("["," ");
s=s.replace("]"," ");
s=s.replace("-"," ");
s=s.replace("+"," ");
s=s.replace("*"," ");
s=s.replace("/"," ");
s=s.replace(">"," ");
s=s.replace("<"," ");
s=s.replace("="," ");
s=s.replace("!"," ");
s=s.replace(":"," ");
s=s.replace("\\"," ");
s=s.replace("[,"," ");
s=s.replace(",]"," ");
s=s.replace("[,]"," ");
s=s.replace("[],"," ");
s=s.replace("],[,"," ");
s=s.replaceAll("[^a-zA-Z]", " ");
String []aa=s.split("\\s");
for(int i=0;i<aa.length;i++)
{
for( j=0;j<key.length;j++)
if(aa[i].equals(key[j]))
{
map.put(key[j], 0);
}
if(key.length<0){
i++;
}
}
for( int i = 0;i<aa.length;i++)
{
for( j=0;j<key.length;j++)
if(aa[i].equals(key[j]))
{ num=(int)map.get(key[j]);
map.put(key[j], num+1);
}
}
Set t=map.keySet();
Object[] arr=t.toArray();
Arrays.sort(arr);
for(Object k:arr){
System.out.println(map.get(k)+"\t"+k);
}
}
}
class panduan{
boolean empty(String s){
if(s.isEmpty())
return false;
return true;
}
}
报表：
踩坑心得：
如何提取两种注释里面的内容，遇到后如何处理？遇到字符串又怎么处理？这些让我想了好长时间，换行注释怎么处理。
改进建议：
用空格来代替注释或者双引号等等。
Java集合框架应用分析总结：
用map集合进行处理，两个参数键值对和数值一一对应，用到了map的get方法和put方法对元素进行处理。
总结：
学到了如何灵活运用正则表达式，由易到难，如何深入理解聚合，对于java面向对象的特点有了更深的了解。学到了多态，继承，接口如何使用。对于更复杂的正则表达式，我还需要多练习，多于类的设计，我还需多思考如何做的最好。希望老师课上可以讲解pta里面需要讲的题，保证大家都要学会，没有疑问，不要拖着问题，作业难度和题量适中。
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