Android: Generate random color on click?

Question

I have an ImageView, in which I am programmaticly creating drawables and presenting them to the user. My goal is to click on said ImageView and change the drawable's color.

How would I go about the random color changing bit? I am currently tinkering with Random(), Color.argb() and a few other things, but I can't seem to get it to work!

Lumis · Accepted Answer · 2013-04-16T18:33:17.357

370

Random rnd = new Random();
paint.setARGB(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));

or

Random rnd = new Random(); 
int color = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));   
view.setBackgroundColor(color);

Though in your case it seems that you want to create a new drawable and assign it to your view. What is actually the drawable in your case? Is it an image, shape, fill...

edited Apr 16 '13 at 18:33

answered Mar 12 '11 at 06:08

Lumis

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16

Shouldn't it be 256 instead of 255 everywhere? The API for nextInt() says "Returns a pseudo-random uniformly distributed int in the half-open range [0, n)" – Catalin Morosan Oct 28 '11 at 13:09
1

Kaciula, you are right the n is excluded: http://docs.oracle.com/javase/1.4.2/docs/api/java/util/Random.html – Lumis Dec 31 '11 at 10:20
int color = 0xFF000000 | rnd.nextInt(0xFFFFFF); " use only 1 random instead of 3" – Umesh Chhabra Jun 01 '16 at 16:43
Color.argb function requires API at least 26 to work. – That's Enam Mar 27 '18 at 17:42
2

@That'sEnam nope, there are two Color.argb functions, one takes int arguments and has existed since API level 1, the one you are talking about takes float arguments and yes, is only since API 26 – Shane Monks O'Byrne Jun 02 '18 at 09:47

ucMedia · Answer 2 · 2022-07-20T12:17:14.903

So if you’re looking for a beautiful color palette, Maybe It's Not Such A Great Idea To use totally random values. This approach might not yield the best results, It always ends up with a selection of similar colors that way too dark or way too bright.

Semi-random approach (Java):

If you need some fresh and shiny colors then use the following simple class, that I wrote previously when I had the same issues. It's semi-random and uses a predefined color palette:

class RandomColors {
    private Stack<Integer> recycle, colors;

    public RandomColors() {
        colors = new Stack<>();
        recycle =new Stack<>();
        recycle.addAll(Arrays.asList(
                0xfff44336,0xffe91e63,0xff9c27b0,0xff673ab7,
                0xff3f51b5,0xff2196f3,0xff03a9f4,0xff00bcd4,
                0xff009688,0xff4caf50,0xff8bc34a,0xffcddc39,
                0xffffeb3b,0xffffc107,0xffff9800,0xffff5722,
                0xff795548,0xff9e9e9e,0xff607d8b,0xff333333
                )
        );
    }

    public int getColor() {
        if (colors.size()==0) {
            while(!recycle.isEmpty())
                colors.push(recycle.pop());
            Collections.shuffle(colors);
        }
        Integer c= colors.pop();
        recycle.push(c);
        return c;
    }
}

Random approach (Java):

But if you're still considering use random approach you may want use this single line instead of multiple lines of code :

int color= ((int)(Math.random()*16777215)) | (0xFF << 24);

The purpose of using this (0xFF << 24) is to set the alpha value to the maximum that means zero transparency.

semi-random (Kotlin)

class RandomColors() {
    private val recycle:Stack<Int> = Stack()
    private val colors:Stack<Int> = Stack()
    init {
        recycle.addAll(
            Arrays.asList(
                // ARGB hex to int >> (0xFFEE5670.toInt(),...)
                -0xbbcca, -0x16e19d, -0x63d850, -0x98c549,  
                -0xc0ae4b, -0xde690d, -0xfc560c, -0xff432c,
                -0xff6978, -0xb350b0, -0x743cb6, -0x3223c7,
                -0x14c5, -0x3ef9, -0x6800, -0xa8de,
                -0x86aab8, -0x616162, -0x9f8275, -0xcccccd
            )
        )
    }

    fun getColor(): Int {
        if (colors.size == 0)
            while (!recycle.isEmpty()) colors.push(recycle.pop())
            Collections.shuffle(colors)
        val c = colors.pop()
        recycle.push(c)
        return c
    }
}

Random approach (Kotlin):

val color = (Math.random() * 16777215).toInt() or (0xFF shl 24)

Yours is the best for a controlled design case ;-) – JWL Aug 09 '19 at 13:25 — JWL, Aug 09 '19 at 13:25

score 20 · Answer 3 · answered Sep 09 '16 at 18:08

to get random color values you can use this method:

public int getRandomColor(){
   Random rnd = new Random();
   return Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
}

then apply to your views:

myView.setBackgroundColor(getRandomColor());

score 8 · Answer 4 · answered Mar 02 '19 at 17:48

8

In Kotlin:

val rnd = Random()
val color = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256))
myView.setBackgroundColor(color)

answered Mar 02 '19 at 17:48

paul_f

1,296
17
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4

make sure to import Random from `java.util` – YTerle Nov 17 '20 at 10:16

score 5 · Answer 5 · answered Jul 05 '14 at 02:42

5

I met this and this is my code,May some help

 /**
 * view-source:http://www.kareno.org/js/colors/ 参考
 *Get Random background color and the text color for the background
 * @return 0--》background
 *          1--》text color
 */
public static  int[] getRandomColor() {
    Random random = new Random();
    int RGB = 0xff + 1;
    int[] colors = new int[2];
    int a = 256;
    int r1 = (int) Math.floor(Math.random() * RGB);
    int r2 = (int) Math.floor(Math.random() * RGB);
    int r3 = (int) Math.floor(Math.random() * RGB);
    colors[0] = Color.rgb(r1, r2, r3);
    if((r1 + r2 + r3) > 450) {
        colors[1] = Color.parseColor("#222222");
    }else{
        colors[1] = Color.parseColor("#ffffff");
    }
    return colors;
}

answered Jul 05 '14 at 02:42

Kevin

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and where is the rgb method ? – Rachit Mishra Oct 06 '14 at 18:51
@twntee rgb is a static method see: [http://developer.android.com/reference/android/graphics/Color.html#rgb(int, int, int)] – Kevin Oct 08 '14 at 04:38
yup got that ! actually there was multiple imports in my file with save name ? – Rachit Mishra Oct 09 '14 at 20:02

score 5 · Answer 6 · answered Dec 19 '17 at 03:25

5

thing.setBackgroundColor(new Random().nextInt());

answered Dec 19 '17 at 03:25

Gary Davies

920
15
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score 3 · Answer 7 · answered Oct 30 '19 at 07:22

3

You can use ColorGenerator for picking the random color

ColorGenerator generator = ColorGenerator.MATERIAL; // or use DEFAULT

int color1 = generator.getRandomColor();      // generate random color

If you want to have the same specific color code for repeated same usernames. you can use like below

public int getColorCode(String userName)
    {
        ColorGenerator generator = ColorGenerator.MATERIAL; // or use DEFAULT
        // generate color based on a key (same key returns the same color), useful for list/grid views
        int colorCode = generator.getColor(userName);

        return colorCode;
    }

answered Oct 30 '19 at 07:22

King of Masses

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what library is ColorGenerator from? – Brill Pappin Mar 11 '23 at 22:30
It's defualy available in android package itself. – King of Masses Mar 15 '23 at 18:45
Its not in the current android versio, or in the material3 library – Brill Pappin Mar 22 '23 at 01:47

score 3 · Answer 8 · answered May 11 '21 at 14:23

Here is an extension to do the same:

fun Int.Companion.randomColor(): Int
{
    return Color.argb(255,
                      Random.nextInt(256),
                      Random.nextInt(256),
                      Random.nextInt(256))
}

and this is the usage:

myTextView.setBackgroundColor(Int.randomColor());

score 2 · Answer 9 · answered Apr 02 '21 at 11:02

2

Simplest Sol... Change the range to avoid dark or light color.. like 30 to 200 to avoid black and white family..

val randomColor: Int
    get() {
        return Color.rgb((30..200).random(),(30..200).random(),(30..200).random())
    }

answered Apr 02 '21 at 11:02

abhi

961
9
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score 1 · Answer 10 · edited Sep 26 '14 at 15:44

1

This is my code I used in an application, it may help you.

It generates a random color on touch

 public boolean onTouch(View v, MotionEvent event) {
            int x = (int)event.getX();
            int y = (int) event.getY();
            float w = v.getWidth();

            if(x < (w * (1.0/3) )){
                layout.setBackgroundColor(Color.rgb(255,x,y));
            }else if(x < (w * (2.0 / 3))){
                layout.setBackgroundColor(Color.rgb(x,255,y));
            }else{
                layout.setBackgroundColor(Color.rgb(x,y,255));
            }
            return true;
   }

edited Sep 26 '14 at 15:44

Peter O.

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answered Sep 26 '14 at 15:36

Sumit

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What exactly does this do? It looks like it's meant to factor in the position of the touch – Kartik Chugh Dec 07 '17 at 07:54
it will change the background of view on touch, when you touch and move, it will generate random color according to x y position and apply to view – Sumit Dec 07 '17 at 16:04

score 1 · Answer 11 · answered Sep 12 '15 at 09:58

1

 public static int randomColor(){
    float[] TEMP_HSL = new float[]{0, 0, 0};
    float[] hsl = TEMP_HSL;
    hsl[0] = (float) (Math.random() * 360);
    hsl[1] = (float) (40 + (Math.random() * 60));
    hsl[2] = (float) (40 + (Math.random() * 60));
    return ColorUtils.HSLToColor(hsl);
}

answered Sep 12 '15 at 09:58

Raghav Thakkar

311
5
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This code generate Blue multiple time , its not random – Hitesh Sahu May 17 '19 at 12:35

Sagar · Answer 12 · 2020-03-04T04:10:51.540

I hope the following two solutions may help you.

There are two way to get random colors programmatically to set to view

1.First solution

public int randomColor()
       {
         Random random= new Random();
         return Color.argb(255, random.nextInt(256), random.nextInt(256), 
         random.nextInt(256));
       }

If you are using in adapter on scroll you may get random colors for the same view this may not look good, to avoid this you can use the second solution.

2.Second Solution

You can use ColorGenerator.DEFAULT instead of ColorGenerator.MATERIAL as per your choice. You can also use any number instead of position

 ColorGenerator generator = ColorGenerator.MATERIAL; 
    int color = generator.getColor(position);
    holder.mEvent_color_strip.setBackgroundColor(color);

what's that ColorGenerator? Where do you get it from? – orelzion May 17 '20 at 09:11 — orelzion, May 17 '20 at 09:11
where do you get ColorGenerator from? – AtomicallyBeyond Dec 30 '21 at 04:23 — AtomicallyBeyond, Dec 30 '21 at 04:23

Zakhar Rodionov · Answer 13 · 2021-08-26T08:40:28.240

1

Random color in Jetpack Compose

val RandomColor
    get() = Color(Random.nextInt(256), Random.nextInt(256), Random.nextInt(256))

edited Aug 26 '21 at 08:40

answered Aug 26 '21 at 08:17

Zakhar Rodionov

1,398
16
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score 0 · Answer 14 · edited Oct 23 '15 at 03:26

0

bb.setBackgroundColor(Color.rgb(
    getRandomInteger(0,255),
    getRandomInteger(0, 255),
    getRandomInteger(0, 255)
));

edited Oct 23 '15 at 03:26

NaviRamyle

3,967
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answered Oct 22 '15 at 22:57

Mukesh Patil

11
1

Sohaib Aslam · Answer 15 · 2018-07-20T19:59:30.243

0

Most Accurate Solution of this problem:

-First, add this in the gradle (app),

compile 'com.github.lzyzsd.randomcolor:library:1.0.0'

then compile and rebuild the app.

-The second step just use it by this way,

RandomColor randomColor = new RandomColor();

Button l = findviewbyid(R.id.B1);
l.setBackgroundColor(randomColor.randomColor());

Reference Link:

https://github.com/lzyzsd/AndroidRandomColor

edited Jul 20 '18 at 19:59

answered Jul 20 '18 at 19:22

Sohaib Aslam

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17
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score 0 · Answer 16 · edited Jan 15 '19 at 07:30

In your case you should do like here, it's work to me

@Override
public void onBindViewHolder(@NonNull WeatherMainAdapter.ViewHolder holder, int position) {
    Random rnd = new Random();
    int color = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
    holder.date.setText(items.get(position).getDt_txt());
    holder.temp.setText(items.get(position).main.getTemp());
    holder.press.setText(items.get(position).main.getPressure());
    holder.cardView.setBackgroundColor(color);
}

score 0 · Answer 17 · answered Jan 24 '19 at 18:28

public static String rndColor()
    {
        Random random = new Random();
        int num = random.nextInt(16777215);
        String hex = "";
        while (num != 0)
        {
            if (num % 16 < 10)
                hex = Integer.toString(num % 16) + hex;
            else
                hex = (char)((num % 16)+55) + hex;
            num = num / 16;
        }

        return "#"+((hex.length()<6)?String.format("%0"+(6-hex.length())+"d", 0):"") + hex;
    }

Android: Generate random color on click?

17 Answers17

Semi-random approach (Java):

Random approach (Java):

semi-random (Kotlin)

Random approach (Kotlin):

Linked

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