編程練習題：（待更新.........）
（10.2~10.3節）+（10.4~10.8節）+（10.9節）+（第10.10~10.11節）
（10.2~10.3節）
*10.1（時間類Time）
首先普及一下（什麼是GMT時間）
GMT時間（格林尼治標準時間）一般指世界時間， 即0時區的區時，比北京時間（東8區）晚8小時；所以，
GMT時間+8小時所得結果就是北京時間。
這是我運行時的時間：![]()
下午15:46
對象1運行的GMT時間與我當前的時間差8小時。（運行正確）
package p10;
public class Time {
private long hour;
private long minute;
private long second;
//無參構造方法
public Time() {
//獲取當前時間,可以用 System.currentTimeMillis()方法獲取當前總的毫秒數
long totalMilliseconds=System.currentTimeMillis();
// 總的毫秒數/1000=總的秒數
long totalSeconds=totalMilliseconds/1000;
//總的秒數%60=當前秒數
long currentSeconds=totalSeconds%60;
this.second=currentSeconds;
// 總的秒數/60=總的分鐘數
long totalMinutes=totalSeconds/60;
//總的分鐘數%60=當前分鐘數
long currentMinutes=totalMinutes%60;
this.minute=currentMinutes;
// 總的分鐘數/60=總的小時數
long totalHours=totalMinutes/60;
//總小時數%24=當前小時數
long currentHours=totalHours%24;
this.hour =currentHours;
}
public Time(long elapseTime) {
// 總的毫秒數/1000=總的秒數
long totalSeconds=elapseTime/1000;
//總的秒數%60=當前秒數
long currentSeconds=totalSeconds%60;
this.second=currentSeconds;
// 總的秒數/60=總的分鐘數
long totalMinutes=totalSeconds/60;
//總的分鐘數%60=當前分鐘數
long currentMinutes=totalMinutes%60;
this.minute=currentMinutes;
// 總的分鐘數/60=總的小時數
long totalHours=totalMinutes/60;
//總小時數%24=當前小時數
long currentHours=totalHours%24;
this.hour =currentHours;
}
public Time(long hour, long minute, long second) {
this.hour=hour;
this.minute=minute;
this.second=second;
}
public long getHour() {
return hour;
}
public long getMinute() {
return minute;
}
public long getSecond() {
return second;
}
public void setTime(long elapseTime) {
// 總的毫秒數/1000=總的秒數
long totalSeconds=elapseTime/1000;
//總的秒數%60=當前秒數
long currentSeconds=totalSeconds%60;
this.second=currentSeconds;
// 總的秒數/60=總的分鐘數
long totalMinutes=totalSeconds/60;
//總的分鐘數%60=當前分鐘數
long currentMinutes=totalMinutes%60;
this.minute=currentMinutes;
// 總的分鐘數/60=總的小時數
long totalHours=totalMinutes/60;
//總小時數%24=當前小時數
long currentHours=totalHours%24;
this.hour =currentHours;
}
}
package p10;
public class Test1 {
public static void main(String[] args) {
Time object1=new Time();
Time object2=new Time(555550000);
//顯示object1的時間
System.out.println("object1's Current time is "
+object1.getHour()+":"+object1.getMinute()+":"+object1.getSecond()+" GMT");
//顯示object2的時間
System.out.println("object2's Current time is "
+object2.getHour()+":"+object2.getMinute()+":"+object2.getSecond()+" GMT");
}
}
10.2（BMI類）
10.3（MyInteger類）
package p10;
public class MyInteger {
//存儲這個對象表示的int值
public int value;
public MyInteger(int value) {
this.value=value;
}
public int getInt() {
return this.value;
}
//判斷是否是偶數，偶數：能被2整除的數，包括正偶數、負偶數和零
public boolean isEven() {
if(getInt() % 2 == 0)
return true;
else
return false;
}
//判斷是否是奇數，奇數：不能被2整除的數
public boolean isOdd() {
if(getInt() % 2 != 0)
return true;
else
return false;
}
//素數：在大於1的整數中，只能被1和這個數本身整除的數，如2,3,5,7,11
public boolean isPrime() {
for(int divisor=2; divisor<=getInt()/2; divisor++) {
if(getInt()%divisor==0) {
return false;
}
}
return true;
}
public static boolean isEven(int value) {
if(value%2==0)
return true;
else
return false;
}
public static boolean isOdd(int value) {
if(value%2!=0)
return true;
else
return false;
}
public static boolean isPrime(int value) {
for(int divisor=2; divisor<=value/2; divisor++) {
if(value%divisor==0) {
return false;
}
}
return true;
}
public static boolean isEven(MyInteger myInteger) {
if(myInteger.value % 2 == 0)
return true;
else
return false;
}
public static boolean isOdd(MyInteger myInteger) {
if(myInteger.value % 2 != 0)
return true;
else
return false;
}
public static boolean isPrime(MyInteger myInteger) {
for(int divisor=2; divisor<=myInteger.value/2; divisor++) {
if(myInteger.value % divisor == 0) {
return false;
}
}
return true;
}
public boolean equals(int count) {
if(this.value==count)
return true;
else
return false;
}
public boolean equals(MyInteger myInteger) {
if(myInteger.value==this.value)
return true;
else
return false;
}
public static int parseInt(char[] ch) {
return Integer.valueOf(new String(ch));
}
public static int parseInt(String s) {
return Integer.valueOf(s);
}
}
10.4(MyPoint類)
package p10;
public class MyPoint {
public double x;
public double y;
public double getX() {
return x;
}
public double getY() {
return y;
}
public MyPoint() {
this.x=0;
this.y=0;
}
public MyPoint(double x, double y) {
this.x=x;
this.y=y;
}
public double distance(MyPoint myPoint) {
return Math.sqrt(Math.pow((this.x-myPoint.x),2) + Math.pow((this.y-myPoint.y),2));
}
public double distance(double x, double y) {
return Math.sqrt(Math.pow((this.x-x),2) + Math.pow((this.y-y),2));
}
}
package p10;
public class Test4 {
public static void main(String[] args) {
MyPoint a=new MyPoint();
MyPoint b=new MyPoint(10,30.5);
System.out.printf("兩點間的距離爲：%.2f", a.distance(b));
}
}
（10.4~10.8節）
*10.5（顯示素數因子）
書上寫有這個類，在本書第320頁，類的實現也有：
package p10;
public class StackOfIntegers {
private int[] elements;
private int size;
public static final int DEFAULT_CAPACITY=16;
public StackOfIntegers() {
this(DEFAULT_CAPACITY);
}
public StackOfIntegers(int capacity) {
elements=new int[capacity];
}
public void push(int value) {
if(size>=elements.length) {
int[] temp=new int[elements.length*2];
System.arraycopy(elements, 0, temp, 0, elements.length);
elements=temp;
}
elements[size++]=value;
}
public int pop() {
return elements[--size];
}
public int peek() {
return elements[size-1];
}
public boolean empty() {
return size==0;
}
public int getSize() {
return size;
}
}
package p10;
import java.util.Scanner;
public class Test5 {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
System.out.print("請輸入一個正整數：");
int number=input.nextInt();
input.close();
//創建一個棧類
StackOfIntegers stack=new StackOfIntegers();
int i=2;
while(number/i!=0) {
if(number%i==0) {
number=number/i;
stack.push(i);
//System.out.println(i);顯示最小因子
}
else if(number%i!=0){
i++;
}
}
//先進先出後進後出
while(!stack.empty()) {
System.out.print(stack.pop()+" ");
}
}
}
*10.5（顯示素數）
package p10;
public class Test6 {
public static void main(String[] args) {
//創建一個棧類
StackOfIntegers stack=new StackOfIntegers();
PrintPrimeNumbers(50);
//先進先出後進後出
while(!stack.empty()) {
System.out.print(stack.pop()+" ");
}
}
//書上183頁代碼
private static void PrintPrimeNumbers(int i) {
final int NUMBER_OF_PRIMES_PER_LINE=10;
int count=0;
int number=2;
while(count<i) {
if(isPrime(number)) {
count++;
if(count % NUMBER_OF_PRIMES_PER_LINE==0) {
//顯示小於120的所有素數
if(number<120) {
System.out.printf("%-5s\n", number);
}
}
else
//顯示小於120的所有素數
if(number<120) { //顯示小於120的所有素數
System.out.printf("%-5s", number);
}
}
number++;
}
}
private static boolean isPrime(int number) {
for(int divisor=2; divisor<=number/2; divisor++) {
if(number%divisor==0) {
return false;
}
}
return true;
}
}
**10.7（遊戲：ATM機）
演示結果：
package p10;
import java.util.Scanner;
import p9.Account;//賬戶類
public class Test7 {
public static void main(String[] args) {
//首先創建一個對象數組：創建一個有10個賬戶的數組
Account[] accountArray=new Account[100];
//初始化對象數組
for(int i=0; i<accountArray.length; i++) {
accountArray[i]=new Account(i,100);
}
//我讓這個大循環進行100次
int n=0;
while(n<100) {
n++;
System.out.println("循環第"+n+"次");
int id=-1;
Scanner input=new Scanner(System.in);
System.out.print("Enter an id:");
//判斷 id 是否正確
while(id==-1) {
String s=input.nextLine();
if( Character.isDigit(s.charAt(0))) {
id=s.charAt(0);
}
else {
System.out.print("Please input an id that is valid:");
}
}
//主菜單循環
int choose=-2;
while(choose!=4) {
System.out.println();
//輸出主菜單
System.out.println(" Main menu \n"
+" 1: check balance \n"
+" 2: withdraw \n"
+" 3: deposit \n"
+" 4: exit");
System.out.print("Enter a choice: ");
choose=input.nextInt();
if(choose==1) {
System.out.println("The balance is "+accountArray[id].getBalance());
}
else if(choose==2) {
System.out.print("Enter an amount to withdraw:");
int withdraw=input.nextInt();
accountArray[id].withDraw(withdraw);
}
else if(choose==3) {
System.out.print("Enter an amount to deposit:");
int deposit=input.nextInt();
accountArray[id].deposit(deposit);
}
else if(choose==4) {
System.out.println();
break;//退出循環
}
}
}
}
}
package p9;
import java.util.Date;
public class Account {
public int id=0;//用戶名
public double balance=0;//餘額
public double annualInteresRate=0;//當前利率
public java.util.Date dateCreated;//存儲開戶時間
//無參構造方法
public Account(){
}
//有參構造方法
public Account(int id, double balance){
this.id=id;
this.balance=balance;
}
public int getId(){
return id;
}
public double getBalance() {
return balance;
}
public double getAnualInterestRate() {
return annualInteresRate;
}
public void setId(int id){
this.id=id;
}
public void setBalance(double balance) {
this.balance=balance;
}
public void setAnnualInterestRate(double annualInterestRate) {
this.annualInteresRate=annualInterestRate;
}
public void setDateCreated(Date dateCreated){
System.out.println(dateCreated.toString());
}
//月利息
public double getMonthlyInterestRate() {
return annualInteresRate/12;
}
//取錢
public double withDraw(double withdraw) {
return this.balance=this.balance-withdraw;
}
//存錢
public double deposit(double deposit) {
return this.balance=this.balance+deposit;
}
}
***10.8（財務：稅款類Tax）
