我必须编写一个可以滚动10个骰子的代码＆＃34; N＆＃34;次数。我必须使用＆＃34; *＆＃34;来制作结果的直方图（10到60）。显示应出现的钟形曲线。如何组合所有不同的ArrayLists，使我的代码看起来更干净？是否有更简单的方法可以一起完成这一切？
我得到了正确的结果;我只需要一种更清晰或更有效的方式来显示我的代码。
public class TenDice {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter number of trials: ");
int roll = scan.nextInt();
ArrayList<String> results10 = new ArrayList<>();
ArrayList<String> results11 = new ArrayList<>();
ArrayList<String> results12 = new ArrayList<>();
ArrayList<String> results13 = new ArrayList<>();
ArrayList<String> results14 = new ArrayList<>();
ArrayList<String> results15 = new ArrayList<>();
ArrayList<String> results16 = new ArrayList<>();
ArrayList<String> results17 = new ArrayList<>();
ArrayList<String> results18 = new ArrayList<>();
ArrayList<String> results19 = new ArrayList<>();
ArrayList<String> results20 = new ArrayList<>();
ArrayList<String> results21 = new ArrayList<>();
ArrayList<String> results22 = new ArrayList<>();
ArrayList<String> results23 = new ArrayList<>();
ArrayList<String> results24 = new ArrayList<>();
ArrayList<String> results25 = new ArrayList<>();
ArrayList<String> results26 = new ArrayList<>();
ArrayList<String> results27 = new ArrayList<>();
ArrayList<String> results28 = new ArrayList<>();
ArrayList<String> results29 = new ArrayList<>();
ArrayList<String> results30 = new ArrayList<>();
ArrayList<String> results31 = new ArrayList<>();
ArrayList<String> results32 = new ArrayList<>();
ArrayList<String> results33 = new ArrayList<>();
ArrayList<String> results34 = new ArrayList<>();
ArrayList<String> results35 = new ArrayList<>();
ArrayList<String> results36 = new ArrayList<>();
ArrayList<String> results37 = new ArrayList<>();
ArrayList<String> results38 = new ArrayList<>();
ArrayList<String> results39 = new ArrayList<>();
ArrayList<String> results40 = new ArrayList<>();
ArrayList<String> results41 = new ArrayList<>();
ArrayList<String> results42 = new ArrayList<>();
ArrayList<String> results43 = new ArrayList<>();
ArrayList<String> results44 = new ArrayList<>();
ArrayList<String> results45 = new ArrayList<>();
ArrayList<String> results46 = new ArrayList<>();
ArrayList<String> results47 = new ArrayList<>();
ArrayList<String> results48 = new ArrayList<>();
ArrayList<String> results49 = new ArrayList<>();
ArrayList<String> results50 = new ArrayList<>();
ArrayList<String> results51 = new ArrayList<>();
ArrayList<String> results52 = new ArrayList<>();
ArrayList<String> results53 = new ArrayList<>();
ArrayList<String> results54 = new ArrayList<>();
ArrayList<String> results55 = new ArrayList<>();
ArrayList<String> results56 = new ArrayList<>();
ArrayList<String> results57 = new ArrayList<>();
ArrayList<String> results58 = new ArrayList<>();
ArrayList<String> results59 = new ArrayList<>();
ArrayList<String> results60 = new ArrayList<>();
for (int i = 0; i < roll; i++) {
double dice1 = Math.random();
dice1 = (int) (dice1 * 6);
double dice2 = Math.random();
dice2 = (int) (dice2 * 6);
double dice3 = Math.random();
dice3 = (int) (dice3 * 6);
double dice4 = Math.random();
dice4 = (int) (dice4 * 6);
double dice5 = Math.random();
dice5 = (int) (dice5 * 6);
double dice6 = Math.random();
dice6 = (int) (dice6 * 6);
double dice7 = Math.random();
dice7 = (int) (dice7 * 6);
double dice8 = Math.random();
dice8 = (int) (dice8 * 6);
double dice9 = Math.random();
dice9 = (int) (dice9 * 6);
double dice10 = Math.random();
dice10 = (int) (dice10 * 6);
double total = dice1 + dice2 + dice3 + dice4 + dice5 +
dice6 + dice7 + dice8 + dice9 + dice10;
if (total == 10) {
results10.add("*");
}
if (total == 11) {
results11.add("*");
}
if (total == 12) {
results12.add("*");
}
if (total == 13) {
results13.add("*");
}
if (total == 14) {
results14.add("*");
}
if (total == 15) {
results15.add("*");
}
if (total == 16) {
results16.add("*");
}
if (total == 17) {
results17.add("*");
}
if (total == 18) {
results18.add("*");
}
if (total == 19) {
results19.add("*");
}
if (total == 20) {
results20.add("*");
}
if (total == 21) {
results21.add("*");
}
if (total == 22) {
results22.add("*");
}
if (total == 23) {
results23.add("*");
}
if (total == 24) {
results24.add("*");
}
if (total == 25) {
results25.add("*");
}
if (total == 26) {
results26.add("*");
}
if (total == 27) {
results27.add("*");
}
if (total == 28) {
results28.add("*");
}
if (total == 29) {
results29.add("*");
}
if (total == 30) {
results30.add("*");
}
if (total == 31) {
results31.add("*");
}
if (total == 32) {
results32.add("*");
}
if (total == 33) {
results33.add("*");
}
if (total == 34) {
results34.add("*");
}
if (total == 35) {
results35.add("*");
}
if (total == 36) {
results36.add("*");
}
if (total == 37) {
results37.add("*");
}
if (total == 38) {
results38.add("*");
}
if (total == 39) {
results39.add("*");
}
if (total == 40) {
results40.add("*");
}
if (total == 41) {
results41.add("*");
}
if (total == 42) {
results42.add("*");
}
if (total == 43) {
results43.add("*");
}
if (total == 44) {
results44.add("*");
}
if (total == 45) {
results45.add("*");
}
if (total == 46) {
results46.add("*");
}
if (total == 47) {
results47.add("*");
}
if (total == 48) {
results48.add("*");
}
if (total == 49) {
results49.add("*");
}
if (total == 50) {
results50.add("*");
}
if (total == 51) {
results51.add("*");
}
if (total == 52) {
results52.add("*");
}
if (total == 53) {
results53.add("*");
}
if (total == 54) {
results54.add("*");
}
if (total == 55) {
results55.add("*");
}
if (total == 56) {
results56.add("*");
}
if (total == 57) {
results57.add("*");
}
if (total == 58) {
results58.add("*");
}
if (total == 59) {
results59.add("*");
}
if (total == 60) {
results60.add("*");
}
}
System.out.println("10: " + results10 + "\n" + "11: " + results11 + "\n" + "12: " + results12 + "\n" + "13: " + results13 + "\n" +
"14: " + results14 + "\n" + "15: " + results15 + "\n" + "16: " + results16 + "\n" + "17: " + results17 + "\n" +
"18: " + results18 + "\n" + "19: " + results19 + "\n" + "20: " + results20 + "\n" + "21: " + results21 + "\n" +
"22: " + results22 + "\n" + "23: " + results23 + "\n" + "24: " + results24 + "\n" + "25: " + results25 + "\n" +
"26: " + results26 + "\n" + "27: " + results27 + "\n" + "28: " + results28 + "\n" + "29: " + results29 + "\n" +
"30: " + results30 + "\n" + "31: " + results31 + "\n" + "32: " + results32 + "\n" + "33: " + results33 + "\n" +
"34: " + results34 + "\n" + "35: " + results35 + "\n" + "36: " + results36 + "\n" + "37: " + results37 + "\n" +
"38: " + results38 + "\n" + "39: " + results39 + "\n" + "40: " + results40 + "\n" + "41: " + results41 + "\n" +
"42: " + results42 + "\n" + "43: " + results43 + "\n" + "44: " + results44 + "\n" + "45: " + results45 + "\n" +
"46: " + results46 + "\n" + "47: " + results47 + "\n" + "48: " + results48 + "\n" + "49: " + results49 + "\n" +
"50: " + results50 + "\n" + "51: " + results51 + "\n" + "52: " + results52 + "\n" + "53: " + results53 + "\n" +
"54: " + results54 + "\n" + "55: " + results55 + "\n" + "56: " + results56 + "\n" + "57: " + results57 + "\n" +
"58: " + results58 + "\n" + "59: " + results59 + "\n" + "60: " + results60);
}
}
答案 0 :(得分：1)
是时候在Java 8中使用Stream API了。
要获得10个骰子的总和，从1到6，你可以做到
Random rnd = new Random();
long sum = IntStream.range(0, 10).map(i -> rand.nextInt(6) + 1).sum();
你可以制作很多卷并分发这些卷。
Map<Long, Long> rollCount =
IntStream.range(0, roll)
.map(r -> rnd.ints(10, 1, 7).sum())
.collect(Collectors.groupingBy(s -> s, Collectors.counting()));
所以这将滚动10个骰子，roll次，并计算每个结果。
您可以使用
打印发行版rollCount.entrySet().stream()
.sorted(e -> e.getKey())
.forEach(e -> System.out.println(e + ": " +
IntStream.range(0, 10).mapToObj(i -> "*").collect(Collectors.joining("")));
让我们说我们不能使用Java 8.我们可以使用循环和更简单的代码。
List<String> countList = new ArrayList<>();
for(int i = 0; i <= 6 * 10; i++)
countList.add(""); // start with nothing.
Random rnd = new Random();
for (int r = 0; r < roll; r++) {
int sum = 0;
for (int i = 0; i < 10; i++)
sum += rnd.randInt(6) + 1;
String stars = countList.get(sum);
stars += "*";
countList.set(sum, stars);
}
答案 1 :(得分：0)
为什么不在每个试验中使用嵌套的arraylist？
public class TenDice {
private static String strJoin(String[] lst, String delimeter) {
StringBuilder sb = new StringBuilder();
for (String s : lst) {
if (s != null) {
sb.append(s).append(delimeter);
}
}
sb.setLength(sb.length() - delimeter.length());
return sb.toString();
}
public static class HistogramBar {
private String[] data;
private int top;
private int size;
public HistogramBar(int size) {
data = new String[size];
}
public void add(String s) {
data[top++] = s;
size++;
}
public String[] getData() {
return data;
}
public int getSize() {
return size;
}
}
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter number of trials: ");
int trials = scan.nextInt();
int numberDice = 10;
int sidesPerDice = 6;
HistogramBar[] results = getDiceTrialHistogram(numberDice, sidesPerDice, trials);
System.out.println(results.length);
for (int i = 0; i < results.length; i++) {
int sum = i + 10;
int length = results[i].getSize();
System.out.printf("%d: %d\n", sum, length);
}
System.out.println("\nHistogram");
for (HistogramBar histBar : results) {
System.out.printf("|%s\n", strJoin(histBar.getData(), ""));
}
}
private static HistogramBar[] getDiceTrialHistogram(int numberDice, int sidesPerDice, int trials) {
int totalSum = numberDice * sidesPerDice;
int size = totalSum - numberDice + 1;
HistogramBar[] results = new HistogramBar[size];
for (int i = 0; i < size; i++) {
results[i] = new HistogramBar(trials);
}
Random r = new Random();
for (int i = 0; i < trials; i++) {
int total = 0;
for (int rolls = 0; rolls < numberDice; rolls++) {
total += r.nextInt(6) + 1;
}
HistogramBar totalList = results[total - numberDice + 1];
totalList.add("*");
}
return results;
}
}
<强>输出
Enter number of trials:
1000
10: 0
11: 0
12: 0
13: 0
14: 0
15: 0
16: 0
17: 0
18: 0
19: 0
20: 1
21: 1
22: 5
23: 7
24: 7
25: 20
26: 28
27: 24
28: 47
29: 40
30: 48
31: 43
32: 69
33: 58
34: 64
35: 77
36: 73
37: 62
38: 85
39: 33
40: 51
41: 36
42: 33
43: 19
44: 29
45: 10
46: 11
47: 7
48: 8
49: 4
50: 0
51: 0
52: 0
53: 0
54: 0
55: 0
56: 0
57: 0
58: 0
59: 0
1000
Histogram
|
|
|
|
|
|
|
|
|
|
|*
|*
|***
|********
|************
|***********************
|*********************
|**************************
|**************************
|*********************************************
|***********************************************
|**********************************************************
|**********************************************************
|**************************************************************************
|*******************************************************************************************
|******************************************************************
|*******************************************************************
|*****************************************************
|********************************************************************
|**************************************************************
|**************************************
|********************************
|**************************************
|***************************
|******************
|***********
|******
|**********
|*****
|****
|*
|
|
|
|
|
|
|
|
|
答案 2 :(得分：0)
在Java 8中
int numberDice = 10;
int sidesPerDice = 6;
int roll = 1000;
Random random = new Random();
int[] freq = IntStream.range(0, roll)
.map(r -> random.ints(numberDice, 1, sidesPerDice + 1).sum())
.collect(() -> new int[numberDice * sidesPerDice + 1], (a, e) -> ++a[e],
(a, b) -> { for (int i = 0; i < a.length; ++i) a[i] += b[i];});
IntStream.range(numberDice, freq.length)
.forEach(i -> System.out.printf("%4d:%4d:%s%n", i, freq[i],
String.format("%" + (freq[i] + 1) + "s", "").substring(1).replaceAll(" ", "*")));
结果
10: 0:
11: 0:
12: 0:
13: 0:
14: 0:
15: 0:
16: 0:
17: 0:
18: 0:
19: 0:
20: 1:*
21: 5:*****
22: 6:******
23: 5:*****
24: 10:**********
25: 18:******************
26: 23:***********************
27: 31:*******************************
28: 40:****************************************
29: 41:*****************************************
30: 45:*********************************************
31: 51:***************************************************
32: 54:******************************************************
33: 62:**************************************************************
34: 72:************************************************************************
35: 76:****************************************************************************
36: 71:***********************************************************************
37: 67:*******************************************************************
38: 71:***********************************************************************
39: 56:********************************************************
40: 46:**********************************************
41: 36:************************************
42: 31:*******************************
43: 24:************************
44: 23:***********************
45: 15:***************
46: 5:*****
47: 5:*****
48: 5:*****
49: 3:***
50: 1:*
51: 1:*
52: 0:
53: 0:
54: 0:
55: 0:
56: 0:
57: 0:
58: 0:
59: 0:
60: 0: