我如何在 Java 中将 RGB 颜色转换为十六进制

Question

I've searched everywhere, but i couldn't find a suiting solution.

I have a RGB color that i want to convert to this format: 0xffffffff

Many answers convert it to this format: #ffffff

Does anyone know how to convert it to this format ( 0xffffffff )?

EDIT: Solved! I actually needed a int but i accidentally said string, woopsie. Seems to work now, thanks!

Snippet:

double frequency = .3;
double r = 255;
double g = 255;
double b = 255;
for (int i = 0; i < 32; ++i)
{
    // I am trying to make a rainbow, hence this for loop and the Math.sin
    r = Math.sin(frequency*i + 0) * 127 + 128;
    g = Math.sin(frequency*i + 2) * 127 + 128;
    b = Math.sin(frequency*i + 4) * 127 + 128;
    int red = (int)r;
    int green = (int)g;
    int blue = (int)b;

    // converting, outputs a string

    System.out.println(result);
}

Answer 1

In case you want the number not as an string , but as an int :

---

0xRRGGBB

RR , GG , BB each represent a value between 0 - 255 (the RGB-values). Each digit of the hex-number can have values ranging from 0 - 16, means that you will need to store numbers up to 16 ^ 6 = 16.777.216‬ -> dataype int should be ok.
Then simply make your int :

int hexval = red * 65536 + green * 256 + blue;

---

Optionally you can output it:

 System.out.printf("0x%06X\\n", hexval);

Answer 2

I've searched everywhere, but i couldn't find a suiting solution.

I have a RGB color that i want to convert to this format: 0xffffffff

Many answers convert it to this format: #ffffff

Does anyone know how to convert it to this format ( 0xffffffff )?

EDIT: Solved! I actually needed a int but i accidentally said string, woopsie. Seems to work now, thanks!

Snippet:

double frequency = .3;
double r = 255;
double g = 255;
double b = 255;
for (int i = 0; i < 32; ++i)
{
    // I am trying to make a rainbow, hence this for loop and the Math.sin
    r = Math.sin(frequency*i + 0) * 127 + 128;
    g = Math.sin(frequency*i + 2) * 127 + 128;
    b = Math.sin(frequency*i + 4) * 127 + 128;
    int red = (int)r;
    int green = (int)g;
    int blue = (int)b;

    // converting, outputs a string

    System.out.println(result);
}

Answer 3

public static int colorToInt(int r, int g, int b) {
    int result = 0;
    result += r;
    result = result << 8;
    result += g;
    result = result << 8;
    result += b;

    return result;
}

Here's an example:

System.out.println(0xffffff); // 16777215
System.out.println(colorToInt(255, 255, 255)); // 16777215

Repl: https://repl.it/repls/IrritatingTwinConsulting .

This function accepts int, instead of double, but I don't think it's a problem. Hope I understood your question correctly.