Random Color Generator

Flutter: How can I make a Random color generator Background

You can use Random class to do that:

But if you want to change the color when button is pressed, you have to use a StatefulWidget. A simple example is like below:

import 'package:flutter/material.dart';
import 'dart:math';

void main() {
  runApp(
    MaterialApp(
      home: MyApp(),
    ),
  );
}

class MyApp extends StatefulWidget {
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  List colors = [Colors.red, Colors.green, Colors.yellow];
  Random random = new Random();

  int index = 0;

  void changeIndex() {
    setState(() => index = random.nextInt(3));
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: RaisedButton(
        onPressed: () => changeIndex(),
        child: Text('Click'),
        color: colors[index],
      ),
    );
  }
}

Also, there is a package called random_pk by pawankumar, that will give us random color each and every time your app's build method get called.

Random color generator

Use getRandomColor() in place of "#0000FF":

function getRandomColor() {

  var letters = '0123456789ABCDEF';

  var color = '#';

  for (var i = 0; i < 6; i++) {

    color += letters[Math.floor(Math.random() * 16)];

  }

  return color;

}

function setRandomColor() {

  $("#colorpad").css("background-color", getRandomColor());

}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div id="colorpad" style="width:300px;height:300px;background-color:#000">

</div>

<button onclick="setRandomColor()">Random Color</button>

Get Random Color

Here's the answer I started posting before you deleted and then un-deleted your question:

public partial class Form1 : Form
{
    private Random rnd = new Random();

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {  
        Color randomColor = Color.FromArgb(rnd.Next(256), rnd.Next(256), rnd.Next(256));

        BackColor = randomColor;
    }
}

Random Color Generator and how to apply it to my existing Gradient

convert to hex
do not reuse the color1/color2 variables
set the color before converting

Note: You many want to loop the second color in case you get the same value

const rgbToHex = rgb => '#' + (rgb.match(/[0-9|.]+/g).map((x, i) => i === 3 ? parseInt(255 * parseFloat(x)).toString(16) : parseInt(x).toString(16)).join('')).padStart(2, '0').toUpperCase();

var css = document.querySelector("h3");
var color1 = document.querySelector(".color1");
var color2 = document.querySelector(".color2");
var body = document.getElementById("gradient");
var button1 = document.querySelector(".button1");

function setGradient() {
  body.style.background =
    "linear-gradient(to right, " +
    color1.value +
    ", " +
    color2.value +
    ")";

  css.textContent = body.style.background + ";";
}

function randomColorGenerator() {
  var col1 = "rgb" + "(" + (Math.floor(Math.random() * 255) +
    ", " +
    Math.floor(Math.random() * 255) +
    ", " +
    Math.floor(Math.random() * 255) +
    ")" + ";");

  var col2 = "rgb" + "(" + (Math.floor(Math.random() * 255) +
    ", " +
    Math.floor(Math.random() * 255) +
    ", " +
    Math.floor(Math.random() * 255) +
    ")" + ";");
    console.log(col1)
    color1.value=rgbToHex(col1)
    color2.value=rgbToHex(col2)
    console.log(color1.value,color2.value)
    setGradient()
}

color1.addEventListener("input", setGradient);

color2.addEventListener("input", setGradient);

button1.addEventListener("click", randomColorGenerator);

<body id="gradient" onload="setGradient()">
  <h1>Background Generator</h1>
  <input class="color1" type="color" name="color1" value="#00ff00">
  <input class="color2" type="color" name="color2" value="#ff0000">
  <h2>Current CSS Background</h2>
  <button class='button1'>Random Color</button>
  <h3></h3>
  <script type="text/javascript" src="script.js"></script>

</body>

Creating random colour in Java?

Use the random library:

import java.util.Random;

Then create a random generator:

Random rand = new Random();

As colours are separated into red green and blue, you can create a new random colour by creating random primary colours:

// Java 'Color' class takes 3 floats, from 0 to 1.
float r = rand.nextFloat();
float g = rand.nextFloat();
float b = rand.nextFloat();

Then to finally create the colour, pass the primary colours into the constructor:

Color randomColor = new Color(r, g, b);

You can also create different random effects using this method, such as creating random colours with more emphasis on certain colours ... pass in less green and blue to produce a "pinker" random colour.

// Will produce a random colour with more red in it (usually "pink-ish")
float r = rand.nextFloat();
float g = rand.nextFloat() / 2f;
float b = rand.nextFloat() / 2f;

Or to ensure that only "light" colours are generated, you can generate colours that are always > 0.5 of each colour element:

// Will produce only bright / light colours:
float r = rand.nextFloat() / 2f + 0.5;
float g = rand.nextFloat() / 2f + 0.5;
float b = rand.nextFloat() / 2f + 0.5;

There are various other colour functions that can be used with the Color class, such as making the colour brighter:

randomColor.brighter();

An overview of the Color class can be read here: http://download.oracle.com/javase/6/docs/api/java/awt/Color.html

Get a Bright Random Colour Python

Create a random HLS color (using numbers around .5 as the "level" parameter and numbers above .5 as the "saturation" parameter) and convert them to RGB:

import random
import colorsys
h,s,l = random.random(), 0.5 + random.random()/2.0, 0.4 + random.random()/5.0
r,g,b = [int(256*i) for i in colorsys.hls_to_rgb(h,l,s)]

That will ensure you'll always have highly saturated, bright colors.