Randomly generated character in a string

Question

I need to generate a random character in string java when the user clicks a button. for example: if we take the cat example, I should use a character in the string, for example:

Gearbox, ACT, TAC, TS

Thanks in advance

Aswan

Answer 1

Hi, thanks for everything, finally I got a solution for my problem.

public String RandomString(String word){

    int no=word.length();
    String temp="";
    String temp2=null;
     while(no>0){
         int genNo=ran.nextInt(word.length());
         if(temp2==null){
             temp2=""+genNo;
             temp=Character.toString(word.charAt(genNo));
             no--;
         }else{
            if(!temp2.contains(""+genNo)){
                temp2=temp2+""+genNo;
                temp=temp+Character.toString(word.charAt(genNo));
                no--;
            }
         }
     }

    if(!temp.equals(word)){
         Log.v("check","temp2 = "+temp2);
         Log.v("check","String = "+temp);
        return temp;
    }else{
        RandomGenerate(word);
    }
    return null;

}

Answer 2

In the Fisher-Yates shuffling algorithm

Fisher-Yates shuffle is a standard shuffle algorithm. Here's the pseudo code:

To shuffle an array a of n elements:
   for i from n - 1 downto 0 do
         j ← random integer with 0 ≤ j ≤ i
         exchange a[j] and a[i]

Here is a simple Java implementation:

static String shuffled(String s) {
    char[] a = s.toCharArray();
    final int N = a.length;
    Random r = new Random();
    for (int i = N - 1; i >= 0; i--) {
        int j = r.nextInt(i + 1);
        swap(a, i, j);
    }
    return new String(a);
}
static void swap(char[] a, int i, int j) {
    char t = a[i];
    a[i] = a[j];
    a[j] = t;
}

Then you can:

    String text = "stackoverflow";
    for (int i = 0; i < 10; i++) {
        System.out.println(shuffled(text));
    }

This will result in 10 line shuffling "stackoverflow"( see also at ideone.com ).

---

Guava + Java Collections Framework

​​ Guava, . :

• Guava Chars.asList(char...), List<Character> char[]. ( ).
• java.util.Collections shuffle(List<?>)

, :

import com.google.common.primitives.*;
import java.util.*;

public class AnagramCreator {
    public static void main(String[] args) {
        String text = "stackoverflow";
        char[] arr = text.toCharArray();
        List<Character> list = Chars.asList(arr);

        for (int i = 0; i < 10; i++) {
            Collections.shuffle(list);
            System.out.println(new String(arr));
        }
    }
}

10 "stackoverflow".

, Guava List<Character> char[]. A char[] autoboxed Character[] ( ), Arrays.asList(T...) .

.

• Java/

• Arrays.asList() ?