[JAVA] I tried to summarize Android development, RGB, hexadecimal number, color implementation from resource files

About Color

I was addicted to it when I was playing with UI design in Android development, so I tried to organize it. You can specify the color from hexadecimal or from the resource file. There is no such thing as a resource file on iOS, so it took me a while to understand the concept. The tricky thing for me was the concept of a Resource file.

Settings from color resources (I made it the top because I am most addicted to it)

A method that can be used if the key is set in color.xml of the Res (Resource) folder. A common method in practice.

Resource.java

Resources res = getResources();
int chocolate_color = res.getColor(R.color.chocolate);

TextView text = new TextView(this);
text.setBackgroundColor(chocolate_color);

color.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="chocolate">#d2691e</color>
</resources>

#Color setting in RGB format

Rgb.java

TextView tv = new TextView(this);
tv.setTextColor(Color.parseColor("#FF00C0"));

// "#FF_00_C0"
// RGB

The parseColor method is public static int parseColor(String colorString) So the argument is of type String and the return value is of type ʻint. Color seems to be ʻint color.

Color setting in ARGB format

Argb.java

TextView tv = new TextView(this);
tv.setTextColor(Color.parseColor("#FF0F00C0"));

// "#FF_0F_00_C0"
// ARGB

Color setting in keyword format

Keywords that can be used are the keywords below

red blue green black white gray cyan magenta yellow lightgraydarkgray

Word.java

TextView tv = new TextView(this);
tv.setTextColor(Color.parseColor("magenta"));

The default constant from the Color class?

--Color.BLACK: Black --Color.BLUE: Blue --Color.CYAN: Cyan --Color.DKGRAY: Dark gray --Color.GRAY: Gray --Color.GREEN: Green --Color.LTGRAY: Light gray --Color.MAGENTA: Magenta --Color.RED: Red --Color.TRANSPARENT: Transparent --Color.WHITE: White --Color.YELLOW: Yellow

How to convert from hexadecimal number to int and set color (remember)

Intcolor.java

String white = "#ffffff";
int whiteInt = Color.parseColor(white);

TextView text = new TextView(this);
text.setBackgroundColor(whiteInt);

How to convert between hexadecimal strings and bytes

hex.java

public static String bin2hex(byte[] data) {
    StringBuffer sb = new StringBuffer();
    for (byte b : data) {
        String s = Integer.toHexString(0xff & b);
        if (s.length() == 1) {
            sb.append("0");
        }
        sb.append(s);
    }
    return sb.toString();
}

public static byte[] hex2bin(String hex) {
    byte[] bytes = new byte[hex.length() / 2];
    for (int index = 0; index < bytes.length; index++) {
        bytes[index] = (byte) Integer.parseInt(hex.substring(index * 2, (index + 1) * 2), 16);
    }
    return bytes;
}

I think that if you hold down this much, you will be able to perform color conversion immediately after seeing this page.