Random string from string array list

Question

I have list of countries in my array, I would like to pick random country from the list (using random probably?), but I haven't found out the answer myself...

This is what I have so far:

String[] list = {"Finland", "Russia", "Latvia", "Lithuania", "Poland"};
Random r = new Random();

score 37 · Accepted Answer · answered Jul 17 '11 at 21:42

37

Try:

list[r.nextInt(list.length)];

answered Jul 17 '11 at 21:42

Burleigh Bear

3,274
22
32

@roni: Burleigh Bear is correct, the value will never be list.length. As per the Java documentation: "Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value **(exclusive)**" – TaylorP Jul 17 '11 at 22:03
@Burleigh Bear Can you please tell me how can I choose a random string from that array and also I want some other string every time. I mean if I don't want to repeat the string value what's modification I need in this code . – Kunu Mar 09 '14 at 14:03
The usual way to do that is to permute the list (i.e. do a shuffle - you can look up Knuth's algorithm for this). Then you can just iterate through the list to return each item successively. – Burleigh Bear Mar 10 '14 at 06:39

Jimale Abdi · Answer 2 · 2019-06-29T10:20:22.923

The accepted answers is not working for me the solution worked for me is

List<String> myList = Arrays.asList("A", "B", "C", "D");

Suppose you have this above ArrayList and you want to randomize it

    Random r = new Random();

    int randomitem = r.nextInt(myList.size());
    String randomElement = myList.get(randomitem);

If you print this randomElement variable you will get random string from your ArrayList

score 2 · Answer 3 · answered Mar 10 '17 at 04:05

2

static String getRandomString(){
        int r = (int) (Math.random()*5);
        String name = new String [] {"India","USA","UK","Russia"}[r];
        return name;
    }

answered Mar 10 '17 at 04:05

Prthbiraj Chouhan

41
3

If you have 4 strings in the array, you should use ```int r = (int) (Math.random()*4);``` – Shai Alon Jun 10 '19 at 10:46

Mike H · Answer 4 · 2016-03-02T14:00:03.813

Ran into a similar problem with pulling a random string from a string array. Found this to work fairly well, I applied it to a button action so with every click a random is drawn(I found with any array size there are multiple instances of the same string being drawn consecutively throughout):

import java.util.*;
import java.util.Random.*;

class Countries {
    public Random g2 = new Random();
    public String[] list = new String[] { "Finland", "Russia",
            "Latvia", "Lithuania", "Poland" };
    String random2;
}

// Applied to a button action:
int INDEXn = g2.nextInt(list.length);
for (int i2 = 0; i2 < INDEXn; i2++) {
    random2 = (String) (list[INDEXn]);
}
System.out.println(random2 + '\n');

The g2 random that is being used by INDEXn is calling a random integer, in this case the defined strings are turned into integer values, from the String array list. The for-loop is cycling through the String array one time. The random2 string is converting the chosen integer from INDEXn to the appropriate string variable in (list[INDEXn]).

score 0 · Answer 5 · edited Feb 04 '13 at 21:56

private void pickText(){ 
    textview textView1= (TextView) findViewById(R.Id.textView1)
    Random eventPicker = new Randorn();
    randomN = eventPicker.nextInt(3) +1; 

    switch (randomN){ 
        case 1: Intent a textview1.setText(StringOne);
        break; 

        case 2: textview1.setText(StringTwo);
        break;

I typed it from my phone there's prob syntax errors but it works.

score 0 · Answer 6 · answered Jun 10 '19 at 10:49

0

Here's a solution in 1 line:

String country = new String[] {"Finland", "Russia", "Latvia", "Lithuania", "Poland"}[(int)(Math.random()*5)];

answered Jun 10 '19 at 10:49

Shai Alon

969
13
21

score 0 · Answer 7 · edited Feb 04 '13 at 21:56

0

list[Math.floor(r.nextFloat()*5.99)]

edited Feb 04 '13 at 21:56

Aliaksandr Belik

12,725
6
64
90

answered Jul 17 '11 at 21:45

roni bar yanai

1,492
10
12

because of the floor. you will not get a uniform distribution as 5 will only be the result when getFloat returns 1.0. – roni bar yanai Jul 17 '11 at 21:59
But there is only 5 entries so you want a uniform distribution for 0..4 not 5. – Peter Lawrey Jul 18 '11 at 10:45
Why floor a float rather than just using an integer? – thegrinner Jul 18 '11 at 16:49
4.99 will means there is slightly less chance of getting 4 as the rest, why not 5? – Peter Lawrey Jul 18 '11 at 19:07

Isaac King · Answer 8 · 2021-11-02T17:39:51.870

-1

import java.util.Random; public static void main (String [] args){

// For this code, we are trying to pic a random day from days

String [] days = {"Sunday","Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday"};

Random rand = new Random();

int Rand_item = rand.nextInt(days.length);

System.out.println(days[Rand_item]);

}

edited Nov 02 '21 at 17:39

answered Nov 01 '21 at 10:08

Isaac King

1
1

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Nov 01 '21 at 15:02

Random string from string array list

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