Random Elements From Array

[Victor]

Just wondering, how do you get x number of elements (pseudo randomly) from an array and set it to a string. I've been Googling but its either random numbers or something like it.

[John]

I have no idea what you mean.

[gszauer]

Im not clear on what you mean eather....
Please provide your array definition.
Im not shure what you mean, but if you are looking to pull a random element from a string of arrays...

public class RandomElement {
  public static int arrayLength, randomElement;
  // Use Array Length to set the length of the array
 
  public static void main (String[] args){
    String[] myArray = [arrayLength];
    // Code to populate array
    randomElement = (int)(Math.random() * (myArray.length - 1));
    System.out.println(myArray[randomElement]);
  }
} 

[Victor]

I want to generate a random 8 digit string from an array

[gszauer]

This should do it mate:

public class GenerateString {
  private static int[] myArray = {5, 2, 6, 9, 8, 7, 4, 1, 2, 3, 7, 5, 6, 8, 5, 8, 7, 0};
  private static int randomNum, randStrLen = 8;
  private static String random;
 
  public static String generateStr(){
    random = "";
    for (int i = 0; i < randStrLen; i++){
        randomNum = (int)(Math.random() * (myArray.length - 1));
        random += myArray[randomNum];
    }
    return random;
  }
 
  public static void main (String[] args){
    System.out.println(generateStr());
  }
} 

Or if you want a re-usable function try this:

public class GenerateString {
 
  // The generateStr function takes 2 arguments
  // and integer array for the array to generate the number from
  // and an integer, wich is the length of the string to be generated
  // this function can be called like so: generateStr(myArray, 8)
  // this function returns a String value
  public static String generateStr(int[] arrayTarget, int randStrLen){
    int randomNum;
    String random = "";
    for (int i = 0; i < randStrLen; i++){
        randomNum = (int)(Math.random() * (arrayTarget.length - 1));
        random += arrayTarget[randomNum];
    }
    return random;
  }
 
  public static void main (String[] args){
    int[] myArray = {5, 2, 6, 9, 8, 7, 4, 1, 2, 3, 7, 5, 6, 8, 5, 8, 7, 0};
    System.out.println(generateStr(myArray, 8));
  }
} 

A nother option would be to create an object... But i dont think it would be practical.

[Victor]

I tried your method and its works, but I do need to be able to get it as a string because I need to display it in a GUI and write it to a file.

[gszauer]

The second method does that, would you like some sample code of how to use it?

[Victor]

Yes please

[gszauer]

The below example should demonstrate.
Note that the first number will be output in the console. the rest is a gui

import javax.swing.*;
 
public class GenerateString {
  
  public static String generateStr(int[] arrayTarget, int randStrLen){
    int randomNum;
    String random = "";
    for (int i = 0; i < randStrLen; i++){
        randomNum = (int)(Math.random() * (arrayTarget.length - 1));
        random += arrayTarget[randomNum];
    }
    return random;
  }
 
  public static void main (String[] args){
    int[] myArray = {5, 2, 6, 9, 8, 7, 4, 1, 2, 3, 7, 5, 6, 8, 5, 8, 7, 0};
    int arrayLength;
    String input;
    String s1, s2, s3;
    
    s1 = "Random string 1: "+generateStr(myArray, 8);
    s2 = "Random string 2: "+generateStr(myArray, 8);
    
    System.out.println(s1);
    JOptionPane.showMessageDialog(null, s2, "Random String", JOptionPane.PLAIN_MESSAGE);
    
    input = JOptionPane.showInputDialog("Please enter string length (no more than 15)");
    arrayLength = Integer.parseInt(input);
    s3 = "Random string 3: "+generateStr(myArray, arrayLength);
    JOptionPane.showMessageDialog(null, s3, "Random String", JOptionPane.PLAIN_MESSAGE);
  }
}