Java语言程序设计与数据结构（基础篇）课后练习题 第十章（一）
10.1
public class dishizhang {
public static void main(String[] args) {
// TODO Auto-generated method stub
Time time1 = new Time();
Time time2 = new Time(555550000);
System.out.printf("%dh/%dm/%ds\n", time1.getHour(), time1.getMinute(), time1.getSecond());
System.out.printf("%dh/%dm/%ds\n", time2.getHour(), time2.getMinute(), time2.getSecond());
}
}
class Time {
private int hour;
private int minute;
private int second;
public Time() {
long t = System.currentTimeMillis();
long seconds = t / 1000;
second = (int) seconds % 60;
seconds /= 60;
minute = (int) seconds % 60;
seconds /= 60;
hour = (int) seconds % 24;
}
public Time(long t) {
long seconds = t / 1000;
second = (int) seconds % 60;
seconds /= 60;
minute = (int) seconds % 60;
seconds /= 60;
hour = (int) seconds % 24;
}
int getHour() {
return hour;
}
int getMinute() {
return minute;
}
int getSecond() {
return second;
}
public void setTime(long elapseTime) {
long seconds = elapseTime / 1000;
second = (int) seconds % 60;
seconds /= 60;
minute = (int) seconds % 60;
seconds /= 60;
hour = (int) seconds % 24;
}
}
10.2
前面课文有提及，添加一个方法就行。
public class BMI {
private String name;
private int age;
private double weight;
private double height;
public static final double KILOGRAMS_PER_POUND = 0.45359237;
public static final double METERS_PER_INCH = 0.0254;
public BMI(String name,int age,double weight,double height){
this.name = name;
this.weight = weight;
this.height = height;
this.age = age;
}
public BMI(String name,double weight,double height){
this(name,20,weight,height);
}
public double getBMI(){
double bmi = weight * KILOGRAMS_PER_POUND / ((height * METERS_PER_INCH) * (height * METERS_PER_INCH));
return Math.round(bmi * 100) / 100.0;
}
public String getStatus(){
double bmi = getBMI();
if (bmi < 18.5)
return "Underweight";
else if (bmi < 25)
return "Normal";
else if (bmi < 30)
return "Overweight";
else
return "Obese";
}
public String getName(){
return name;
}
public int getAge(){
return age;
}
public double getWeight(){
return weight;
}
public double getHeight() {
return height;
}
public BMI(String name,int age,double weight,double feet,double inches){
this.name = name;
this.age = age;
this.weight = weight;
this.height = feet * 12 + inches;
}
}
10.3
import java.util.Scanner;
public class dishizhang {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
System.out.print("Enter n1: ");
MyInteger n1 = new MyInteger(input.nextInt());
System.out.println("Is n1 a even?" + '\t' + n1.isEven());
System.out.println("Is n1 a prime?" + '\t' + n1.isPrime());
System.out.println("Is n1 a prime2?" + '\t' + MyInteger.isPrime(n1));
System.out.println("Is n1 a odd?" + '\t' + n1.isOdd());
System.out.println("Is n1 a odd2?" + '\t' + MyInteger.isOdd(n1));
System.out.print("Enter n2: ");
MyInteger n2 = new MyInteger(input.nextInt());
System.out.println("Are n1 and n2 equal?" + '\t' + n1.equals(n2));
System.out.println("Are n1 and 5 equal?" + '\t' + n1.equals(5));
}
}
class MyInteger {
private int value;
public MyInteger(int value) {
this.value = value;
}
public int getValue() {
return value;
}
public static boolean isEven(int value) {
if (value % 2 == 0)
return true;
else
return false;
}
public boolean isEven() {
return isEven(value);
}
public boolean isOdd() {
return isOdd(value);
}
public boolean isOdd(int value) {
if (value % 2 != 0)
return true;
else
return false;
}
public boolean isPrime() {
return isPrime(value);
}
public static boolean isPrime(int value) {
for (int i = 2; i < value - 1; i++)
if (value % i == 0)
return false;
return true;
}
public static boolean isEven(MyInteger m) {
if (m.getValue() % 2 == 0)
return true;
else
return false;
}
public static boolean isOdd(MyInteger m) {
if (m.getValue() % 2 != 0)
return true;
else
return false;
}
public static boolean isPrime(MyInteger m) {
for (int i = 2; i < m.getValue() - 1; i++) {
if (m.getValue() % 2 == 0)
return false;
}
return true;
}
public boolean equals(int value) {
if (this.value == value)
return true;
else
return false;
}
public boolean equals(MyInteger m) {
if (this.value == m.getValue())
return true;
else
return false;
}
}
10.4
public class dishizhang {
public static void main(String[] args) {
// TODO Auto-generated method stub
MyPoint p1 = new MyPoint(0,0);
MyPoint p2 = new MyPoint(10,30.5);
System.out.println("The distance is "+p1.distance(p2));
}
}
class MyPoint{
private double x;
private double y;
MyPoint(){
this.x = 0.0;
this.y = 0.0;
}
public MyPoint(double x,double y){
this.x = x;
this.y = y;
}
public double distance(double x,double y){
double s;
s = Math.sqrt((this.x - x)*(this.x - x)+(this.y - y)*(this.y - y));
return s;
}
public double distance(MyPoint mypoint){
double s;
s = Math.sqrt((this.x - mypoint.getX()) * (this.x - mypoint.getX())+(this.y - mypoint.getY()) * (this.y - mypoint.getY()));
return s;
}
public double getX(){
return x;
}
public double getY(){
return y;
}
}
10.5
import java.util.Arrays;
import java.util.Scanner;
public class dishizhang {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print("Please input a integer :");
Scanner input = new Scanner(System.in);
int integer=input.nextInt();
StackOfIntegers stackOfIntegers = new StackOfIntegers(integer);
int[] i=stackOfIntegers.Prime();
System.out.print("All the prime factors of the "+integer+ " are :");
System.out.print(Arrays.toString(i));
}
}
class StackOfIntegers{
private int integer;
public StackOfIntegers(int integer) {
this.integer = integer;
}
private static int k = 0;
private static int l = 0;
public int[] GetPrime() {
int[] getPrime = new int[this.integer];
boolean isPrime = true;
for (int i = 2; i < this.integer; i++) {
for (int j = 2; j < i; j++) {
if (i % j == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
getPrime[k] = i;
k++;
} else isPrime = true;
}
return getPrime;
}
public int[] Prime() {
int[] get = GetPrime();
int[] prime1 = new int[k];
boolean judge=false;
while (this.integer != 0) {
for (int a = k - 1; a >= 0; a--) {
if ((int) (this.integer / get[a]) == (double) this.integer / get[a]) {
prime1[l] = get[a];
this.integer /= get[a];
l++;
}
if (integer == get[a] || integer == 1) {
prime1[l] = get[a];
judge=true;
break;
}
}
if (judge)
break;
}
int[] prime=new int[l+1];
for (int i=0;i}
10.6
import java.util.Arrays;
import java.util.Scanner;
public class dishizhang {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print("Please input a integer :");
Scanner input = new Scanner(System.in);
int integer=input.nextInt();
StackOfIntegers stackOfIntegers = new StackOfIntegers(integer);
int[] i = stackOfIntegers.GetPrime();
System.out.print("All primes less than "+integer+ " are: ");
for(int j=0;j}
class StackOfIntegers{
```
private int integer;
public StackOfIntegers(int integer) {
this.integer = integer;
}
private static int k = 0;
public int[] GetPrime() {
int[] getPrime = new int[this.integer];
boolean isPrime = true;
for (int i = 2; i < this.integer; i++) {
for (int h = 2; h < i; h++) {
if (i % h == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
getPrime[k] = i;
k++;
} else isPrime = true;
}
return reverse(getPrime);
}
public int[] reverse(int[] prime){
int tmp;
for(int i=0; i}
10.7
import java.util.Date;
import java.util.Scanner;
public class dishizhang {
public static void main(String[] args) {
Account[] accounts = new Account[10];
for (int i = 0; i < 10; i++)
accounts[i] = new Account(1, 100);
System.out.print("Enter an id:");
Scanner input = new Scanner(System.in);
int id = input.nextInt();
while (id < 0 || id > 9) {
System.out.print("The if is nonExistent,please input again:");
id = input.nextInt();
}
mainMenu();
int choice = input.nextInt();
boolean judge = choice == 1 || choice == 2 || choice == 3;
while (judge) {
switch (choice) {
case 1:
System.out.println("The balance is "+accounts[id].getBalance());
break;
case 2:
System.out.print("Enter an amount to withdraw: ");
double withdraw = input.nextDouble();
accounts[id].withdraw(withdraw);
break;
case 3:
System.out.print("Enter an amount to deposit:");
double deposit=input.nextDouble();
accounts[id].deposit(deposit);
break;
}
mainMenu();
choice=input.nextInt();
judge = choice == 1 || choice == 2 || choice == 3;
}
dishizhang.main(args);
}
public static void mainMenu(){
System.out.println("Main menu");
System.out.println("1: check balance ");
System.out.println("2: withdraw ");
System.out.println("3: deposit ");
System.out.println("4: exit ");
System.out.print("Enter a choice: ");
}
}
class Account {
public Account() {
dateCreated = new Date();
}
public Account(int id,double balance){
this.id = id;
this.balance = balance;
dateCreated = new Date();
}
private int id;
private double balance;
private double annualInterestRate;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
public double getAnnualInterestRate() {
return annualInterestRate;
}
public void setAnnualInterestRate(double annualInterestRate) {
this.annualInterestRate = annualInterestRate;
}
private Date dateCreated=new Date();
public void Account() {
}
public double getMonthlyInterest() {
return balance*(annualInterestRate/100/12);
}
public void withdraw(double reduce) {
balance-=reduce;
}
public void deposit(double increase) {
balance+=increase;
}
public Date getDateCreated() {
return dateCreated;
}
}