我必须创建一个简单的Java彩票号码生成器，模仿Lotto 6/49(加拿大安大略省(。询问用户他们希望生成多少票。门票必须按数字升序排列，并且没有重复项。例如，如果我想要 3 张票，输出可能是：
8 12 17 25 32 47
6 10 21 30 39 42
1 8 16 37 45 49
尝试对数字进行排序时出现问题。我们被教导使用气泡排序，但是我的重复检查无法正常工作，因此我最终会得到如下所示的输出：
8 18 29 29 29 29
4 12 18 18 24 24
4 12 18 24 46 46
我的代码如下：
// The "Lotto" class.
import java.awt.*;
import hsa.Console;
public class Lotto
{
static Console c; // The output console
public static void main (String[] args)
{
c = new Console ();
int t = 0;
int num[];
num = new int[10];
c.println("How many Lotto 6/49 tickets do you wish to generate?");
t = c.readInt();
c.println("****************");
for (int a = 1; a <= t; a++)
{
for (int i = 1; i <= 6; i++)
{
num[i] = (int)(Math.random() * 49 + 1);
for (int x = 1; x <= 6; x++) // duplicate check
{
for (int y = x + 1; y <= 7; y++)
{
if (num[x] == num[y])
{
num[y] = (int)(Math.random() * 49 + 1);
}
}
} // end check
for (int p = 1; p <=6; p++) // start sort
{
for (int q = 1; q <=7; q++)
{
if (num[p] < num[q])
{
int temp = num[p];
num[p] = num[q];
num[q] = temp;
}
}
} // end sort
c.print(num[i] + " ");
}
c.println();
}
} // main method
} // Lotto class
对此事的任何帮助或解决方案将不胜感激。谢谢！
这是一个
糟糕的抽象。 我建议将所有逻辑嵌入到类中。 面向对象编程是关于抽象、封装和隐藏细节的。
以下是我的做法：
package gambling;
import java.util.Random;
import java.util.Set;
import java.util.TreeSet;
/**
* Created by Michael
* Creation date 3/21/2017.
* @link https://stackoverflow.com/questions/42932262/java-creating-simple-lottery-number-generator
*/
public class LottoTicket {
public static final int DEFAULT_NUM_TICKETS = 10;
public static final int DEFAULT_MAX_VALUE = 49;
public static final int DEFAULT_NUM_VALUES = 6;
private Random random;
public static void main(String[] args) {
int numTickets = (args.length > 0) ? Integer.parseInt(args[0]) : DEFAULT_NUM_TICKETS;
LottoTicket lottoTicket = new LottoTicket();
for (int i = 0; i < numTickets; ++i) {
System.out.println(lottoTicket.getNumbers(DEFAULT_NUM_VALUES, DEFAULT_MAX_VALUE));
}
}
public LottoTicket() {
this(null);
}
public LottoTicket(Long seed) {
this.random = (seed != null) ? new Random(seed) : new Random();
}
public Set<Integer> getNumbers(int numValues, int maxValue) {
Set<Integer> numbers = new TreeSet<>();
while (numbers.size() < numValues) {
numbers.add(this.random.nextInt(maxValue) + 1);
}
return numbers;
}
}
实际上，您的气泡排序和重复检查都不起作用。
对于重复检查，如果检测到重复项，则会生成一个新的随机数，但无法阻止代码生成相同的重复项。尝试将if (num[x] == num[y])更改为while (num[x] == num[y])
对于气泡排序，我认为您误解了算法。一般形式应为：
boolean changed = false;
do {
for (int i = 0; i < size - 1; i++) {
if (num[i] > num[i+1]) {
// swap
changed = true;
}
}
} while (changed);
虽然我认为这超出了您的问题范围，但可以使用 Java 8 在一个语句中生成整个集合：
int[] nums = random.ints(1, 50).distinct().limit(6).sorted().toArray();
这被解释为：生成 1 到 49 之间的无限随机数流，删除重复项，获取前 6 个，对它们进行排序并将它们作为数组返回。
这是我
的版本：
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
class LotoTicket {
private static final int NUM_NUMBERS = 6;
private static final int NUM_BALLS = 99;
private static final Random random = new Random();
private final int[] numbers;
private LotoTicket(final int[] numbers) {
this.numbers = numbers;
}
public static LotoTicket generateTicket() {
final int[] numbers = new int[NUM_NUMBERS];
final List<Integer> ballPool = IntStream.range(1, 1 + NUM_BALLS)
.mapToObj(i -> i)
.collect(Collectors.toList());
for (int i = 0; i < NUM_NUMBERS; i++) {
final int draw = random.nextInt(NUM_BALLS - i);
numbers[i] = ballPool.remove(draw);
}
Arrays.sort(numbers);
return new LotoTicket(numbers);
}
public int[] getNumbers() {
return numbers;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("LotoTicket{");
sb.append("numbers=").append(Arrays.toString(numbers));
sb.append('}');
return sb.toString();
}
public static void main(final String... args) {
System.out.println(LotoTicket.generateTicket());
System.out.println(LotoTicket.generateTicket());
System.out.println(LotoTicket.generateTicket());
}
}
编辑
这是一个兼容java1.5的版本，并实现了一个简单的气泡排序：
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
class LotoTicket {
private static final int NUM_NUMBERS = 6;
private static final int NUM_BALLS = 99;
private static final Random random = new Random();
private final int[] numbers;
private LotoTicket(final int[] numbers) {
this.numbers = numbers;
}
public static LotoTicket generateTicket() {
final int[] numbers = new int[NUM_NUMBERS];
final List<Integer> ballPool = new ArrayList<Integer>();
for (int i = 0; i < NUM_BALLS; i++) {
ballPool.add(i, i + 1);
}
for (int i = 0; i < NUM_NUMBERS; i++) {
final int draw = random.nextInt(NUM_BALLS - i);
numbers[i] = ballPool.remove(draw);
}
bubbleSort(numbers);
return new LotoTicket(numbers);
}
private static void bubbleSort(final int[] numbers) {
if (numbers.length <= 1) {
return;
}
boolean sorted;
do {
sorted = true;
for (int i = 1; i < numbers.length; i++) {
if (numbers[i - 1] > numbers[i]) {
final int temp = numbers[i];
numbers[i] = numbers[i - 1];
numbers[i - 1] = temp;
sorted = false;
}
}
} while (sorted == false);
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("LotoTicket{");
sb.append("numbers=").append(Arrays.toString(numbers));
sb.append('}');
return sb.toString();
}
public static void main(final String... args) {
System.out.println(LotoTicket.generateTicket());
System.out.println(LotoTicket.generateTicket());
System.out.println(LotoTicket.generateTicket());
}
}