Java Join Text Without Losing the Calculation

Understand the idea

The + operator performs arithmetic for numeric operands and concatenation once a String participates. Evaluation proceeds according to grouping and operand order, so a label can change the meaning of a following +. StringBuilder is mutable and useful for assembling a result inside one method. It is not a thread-safe shared buffer by default. Escape sequences such as , , \" and \\ represent characters inside a string literal.

Run it locally

Use a local JDK 21 or newer. Save the complete example as Main.java in a separate lab folder, then compile and run it with the commands below. Java examples do not run in Bhylu’s browser playground. The -ea option enables assertion checks used by some lessons.

JDK and terminal setup

javac --release 21 -encoding UTF-8 -d out Main.java
java -ea -cp out Main

A worked example

public class Main {
    public static void main(String[] args) {
        int morning = 4, evening = 7;
        StringBuilder report = new StringBuilder();
        report.append("Bookings: ").append(morning + evening);
        report.append("\nLabel: \"Workshop\"");
        System.out.println(report);
    }
}

Expected output

Bookings: 11
Label: "Workshop"

The numeric addition happens inside the append argument, giving eleven. The builder then appends a new line and quoted text. println accepts the builder and uses its string representation. The visible quotation marks are part of the produced text; the backslashes that escape them belong to the Java source syntax.