Tag Archives: coding

23 Sep

Colour console output in Java

Wondering how to colour System.out.println console output in Java? Use standard ANSI escape sequences (just concatenate them with your output, and use ANSI_RESET to go back to default). This works in Linux, MacOS, Windows Powershell and Cygwin on Windows. It DOESN’T work in Windows Command Prompt.

Here are some handy constants:

public static final String ANSI_RESET  = "\u001B[0m";

public static final String ANSI_BLACK  = "\u001B[30m";
public static final String ANSI_RED    = "\u001B[31m";
public static final String ANSI_GREEN  = "\u001B[32m";
public static final String ANSI_YELLOW = "\u001B[33m";
public static final String ANSI_BLUE   = "\u001B[34m";
public static final String ANSI_PURPLE = "\u001B[35m";
public static final String ANSI_CYAN   = "\u001B[36m";
public static final String ANSI_WHITE  = "\u001B[37m";

public static final String ANSI_BRIGHT_BLACK  = "\u001B[90m";
public static final String ANSI_BRIGHT_RED    = "\u001B[91m";
public static final String ANSI_BRIGHT_GREEN  = "\u001B[92m";
public static final String ANSI_BRIGHT_YELLOW = "\u001B[93m";
public static final String ANSI_BRIGHT_BLUE   = "\u001B[94m";
public static final String ANSI_BRIGHT_PURPLE = "\u001B[95m";
public static final String ANSI_BRIGHT_CYAN   = "\u001B[96m";
public static final String ANSI_BRIGHT_WHITE  = "\u001B[97m";

public static final String[] FOREGROUNDS = {
        ANSI_BLACK, ANSI_RED, ANSI_GREEN, ANSI_YELLOW,
        ANSI_BLUE, ANSI_PURPLE, ANSI_CYAN, ANSI_WHITE,
        ANSI_BRIGHT_BLACK, ANSI_BRIGHT_RED, ANSI_BRIGHT_GREEN, ANSI_BRIGHT_YELLOW,
        ANSI_BRIGHT_BLUE, ANSI_BRIGHT_PURPLE, ANSI_BRIGHT_CYAN, ANSI_BRIGHT_WHITE
};

public static final String ANSI_BG_BLACK  = "\u001B[40m";
public static final String ANSI_BG_RED    = "\u001B[41m";
public static final String ANSI_BG_GREEN  = "\u001B[42m";
public static final String ANSI_BG_YELLOW = "\u001B[43m";
public static final String ANSI_BG_BLUE   = "\u001B[44m";
public static final String ANSI_BG_PURPLE = "\u001B[45m";
public static final String ANSI_BG_CYAN   = "\u001B[46m";
public static final String ANSI_BG_WHITE  = "\u001B[47m";

public static final String ANSI_BRIGHT_BG_BLACK  = "\u001B[100m";
public static final String ANSI_BRIGHT_BG_RED    = "\u001B[101m";
public static final String ANSI_BRIGHT_BG_GREEN  = "\u001B[102m";
public static final String ANSI_BRIGHT_BG_YELLOW = "\u001B[103m";
public static final String ANSI_BRIGHT_BG_BLUE   = "\u001B[104m";
public static final String ANSI_BRIGHT_BG_PURPLE = "\u001B[105m";
public static final String ANSI_BRIGHT_BG_CYAN   = "\u001B[106m";
public static final String ANSI_BRIGHT_BG_WHITE  = "\u001B[107m";

public static final String[] BACKGROUNDS = {
        ANSI_BG_BLACK, ANSI_BG_RED, ANSI_BG_GREEN, ANSI_BG_YELLOW,
        ANSI_BG_BLUE, ANSI_BG_PURPLE, ANSI_BG_CYAN, ANSI_BG_WHITE,
        ANSI_BRIGHT_BG_BLACK, ANSI_BRIGHT_BG_RED, ANSI_BRIGHT_BG_GREEN, ANSI_BRIGHT_BG_YELLOW,
        ANSI_BRIGHT_BG_BLUE, ANSI_BRIGHT_BG_PURPLE, ANSI_BRIGHT_BG_CYAN, ANSI_BRIGHT_BG_WHITE };
17 May

Java: Read contents of resource file to String

If you have a resource text file – even if packaged in a JAR file – you can use the following Java 8(+) code to read the contents into a String. This code will also work in a static method (hence the ClassLoader.getSystemClassLoader()). If you’re in a normal method you can use the current instance’s classloader instead.

String contents = "";
ClassLoader classLoader = ClassLoader.getSystemClassLoader();
InputStream inputStream = classLoader.getResourceAsStream(filename);
if (inputStream != null) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        contents = reader.lines().collect(Collectors.joining(System.lineSeparator()));
}