Java 如何打乱字符串中的字符
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How to shuffle characters in a string
提问by user339108
How do I shuffle the characters in a string (e.g. hello could be ehlol or lleoh or ...). I don't want to use the Collections.shuffle(...)method, is there anything simpler?
我如何打乱字符串中的字符（例如，hello 可以是 ehlol 或 lleoh 或 ...）。我不想用这个Collections.shuffle(...)方法，有没有更简单的方法？
采纳答案by bragboy
I dont know anything simpler. But you can use the Math.rand() functionality to generate a random number within the range of the character's length without replace and that would give you a shuffled output
我不知道什么更简单。但是您可以使用 Math.rand() 功能在字符长度范围内生成一个随机数而无需替换，这会给您一个混洗的输出
public class Shuffle {
public static void main(String[] args) {
Shuffle s = new Shuffle();
s.shuffle("hello");
}
public void shuffle(String input){
List<Character> characters = new ArrayList<Character>();
for(char c:input.toCharArray()){
characters.add(c);
}
StringBuilder output = new StringBuilder(input.length());
while(characters.size()!=0){
int randPicker = (int)(Math.random()*characters.size());
output.append(characters.remove(randPicker));
}
System.out.println(output.toString());
}
}
/*
Sample outputs
hlleo
llheo
leohl
lleho
*/
回答by Tarski
You could iterate over all the characters, comparing each one with the next. Then if Math.rand() > 0.5 swap this character with the next, otherwise move on to the next character.
您可以遍历所有字符，将每个字符与下一个进行比较。然后如果 Math.rand() > 0.5 将这个字符与下一个交换，否则移动到下一个字符。
回答by amra
E.g.:
例如：
static String shuffle(String text){
if (text.length()<=1)
return text;
int split=text.length()/2;
String temp1=shuffle(text.substring(0,split));
String temp2=shuffle(text.substring(split));
if (Math.random() > 0.5)
return temp1 + temp2;
else
return temp2 + temp1;
}
回答by user272043
class ShuffleString
{
public static String shuffle(String s)
{
String shuffledString = "";
while (s.length() != 0)
{
int index = (int) Math.floor(Math.random() * s.length());
char c = s.charAt(index);
s = s.substring(0,index)+s.substring(index+1);
shuffledString += c;
}
return shuffledString;
}
}
public class foo{
static public void main(String[] args)
{
String test = "hallo";
test = ShuffleString.shuffle(test);
System.out.println(test);
}
}
Output: ahlol
输出：ahlo
回答by Nick Bolton
Not great performance, but quite readable in my opinion:
不是很好的表现，但在我看来相当可读：
public static String shuffleString(String string)
{
List<String> letters = Arrays.asList(string.split(""));
Collections.shuffle(letters);
String shuffled = "";
for (String letter : letters) {
shuffled += letter;
}
return shuffled;
}
回答by Karl Giesing
Here's code that requires neither recursion, nor converting to a Collection.
这是既不需要递归也不需要转换为集合的代码。
public static String shuffle(String string) {
StringBuilder sb = new StringBuilder(string.length());
double rnd;
for (char c: string.toCharArray()) {
rnd = Math.random();
if (rnd < 0.34)
sb.append(c);
else if (rnd < 0.67)
sb.insert(sb.length() / 2, c);
else
sb.insert(0, c);
}
return sb.toString();
}
回答by mac
Not sure why you wouldn't want to use shuffle, unless it's for school. ;)
不知道为什么你不想使用 shuffle，除非它是为了学校。;)
And if you're concerned with performance, you definitely can't use any solution that concatenates strings with "+".
如果你关心性能，你绝对不能使用任何用“+”连接字符串的解决方案。
Here's the most compact solution I could come up with:
这是我能想到的最紧凑的解决方案：
public static String shuffle(String string) {
if (StringUtils.isBlank(string) {
return string;
}
final List<Character> randomChars = new ArrayList<>();
CollectionUtils.addAll(randomChars, ArrayUtils.toObject(string.toCharArray()));
Collections.shuffle(randomChars);
return StringUtils.join(randomChars, "");
}
回答by cherouvim
How about this:
这个怎么样：
public static String shuffle(String text) {
char[] characters = text.toCharArray();
for (int i = 0; i < characters.length; i++) {
int randomIndex = (int)(Math.random() * characters.length);
char temp = characters[i];
characters[i] = characters[randomIndex];
characters[randomIndex] = temp;
}
return new String(characters);
}
回答by s13o
String shuffled;
do {
shuffled = Stream.of(text.split("")).sorted((o1, o2) -> ThreadLocalRandom.current().nextInt(3) - 1).collect(Collectors.joining());
}while(shuffled.equals(text));
回答by Chris
What an annoying problem. I finally ended up with this:
多么烦人的问题。我最终得到了这个：
import java.util.Collections;
import com.google.common.primitives.Chars;
import org.apache.commons.lang3.StringUtils;
String shuffle(String s) {
List<Character> chars = Chars.asList(s.toCharArray());
Collections.shuffle(chars);
return StringUtils.join(chars.stream().toArray());
}
Yes, two libraries :)
是的，两个图书馆:)
