Option 1: Using the <pre> tag

Here’s a first option, using the <pre> tag and formatted as a block quote. This tag applies a monospace font and keeps the line breaks exactly as written. A horizontal scroll bar will be added when there are longer lines:

// This program demonstrates variables, literal constants, and data types.

public class Main {
    public static void main(String[] args) {
        int i;
        double d;
        String s;
        boolean b;
        
        i = 1234567890;
        d = 1.23456789012345;
        s = "string";
        b = true;

        System.out.println("Integer i = " + i);
        System.out.println("Double d = " + d);
        System.out.println("String s = " + s);
        System.out.println("Boolean b = " + b);
    }
}

Option 2: Using a text box

In this case, the text with the <pre> tag is included in a shaded text box without the block quote format:

// This program demonstrates variables, literal constants, and data types.

public class Main {
    public static void main(String[] args) {
        int i;
        double d;
        String s;
        boolean b;
        
        i = 1234567890;
        d = 1.23456789012345;
        s = "string";
        b = true;

        System.out.println("Integer i = " + i);
        System.out.println("Double d = " + d);
        System.out.println("String s = " + s);
        System.out.println("Boolean b = " + b);
    }
}

Option 3: Inserting code within a paragraph using a <code> tag

If you want to note a smaller piece of code within a paragraph, use the <code> tag. For instance, System.out.println("Integer i = " + i); can be highlighted like this. In this case, <code> just applies the monospace font; text colour has been adjusted separately.