Java Academy · Lesson

Indentation and Stripping

Control incidental whitespace.

Indentation and Stripping is a free Java Academy lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Incidental vs Essential Whitespace

When you indent a text block to match your code, that indentation is incidental and should not be part of the string. Java strips it automatically, keeping only essential whitespace.

The Closing Delimiter Sets the Margin

Java looks at all content lines and the closing """ to find the common leftmost non-blank column. Everything to the left of that margin is removed.

public class Main {
    public static void main(String[] args) {
        String text = """
            Hello
            World
            """;
        System.out.println("[" + text + "]");
    }
}

Moving the Closing Quotes Left

If the closing """ sits further left than the content, the extra leading spaces on each line are kept as essential whitespace.

public class Main {
    public static void main(String[] args) {
        String text = """
                Hello
                World
        """;
        System.out.print(text);
    }
}

Trailing Whitespace Is Removed

Spaces at the end of each line are stripped automatically. This prevents invisible trailing-space bugs that plague ordinary strings.

public class Main {
    public static void main(String[] args) {
        String text = """
            line one
            line two
            """;
        for (String line : text.split("\n")) {
            System.out.println("<" + line + ">");
        }
    }
}

The stripIndent Method

The String.stripIndent() method applies the same incidental-whitespace algorithm to any string at runtime. It is what text blocks use under the hood.

public class Main {
    public static void main(String[] args) {
        String raw = "    a\n    b\n    c\n";
        System.out.print(raw.stripIndent());
    }
}

Controlling Indentation Inside

Indentation relative to the margin is preserved. Here the second line is indented more than the first, and that extra indent stays in the output.

public class Main {
    public static void main(String[] args) {
        String tree = """
            root
              child
                grandchild
            """;
        System.out.print(tree);
    }
}

The indent Method

String.indent(int n) adds n spaces to the start of every line and ensures a trailing newline. It is handy for nesting blocks of text.

public class Main {
    public static void main(String[] args) {
        String text = """
            a
            b
            """;
        System.out.print(text.indent(4));
    }
}

strip vs trim

Use strip() to remove leading and trailing whitespace from the whole block. Unlike the older trim(), strip() is Unicode-aware.

public class Main {
    public static void main(String[] args) {
        String text = """
            
            content
            
            """;
        System.out.println("[" + text.strip() + "]");
    }
}

Closing Quotes on Their Own Line

If the closing """ is on its own line, the string ends with a trailing newline. Place it right after the last character to drop that newline.

public class Main {
    public static void main(String[] args) {
        String withNewline = """
            done
            """;
        String noNewline = """
            done""";
        System.out.println("A:" + withNewline.length());
        System.out.println("B:" + noNewline.length());
    }
}

Aligning With Your Code

You can indent the whole block to match surrounding code for readability, and the incidental indentation disappears from the value.

public class Main {
    static String menu() {
        return """
                Start
                Options
                Quit
                """;
    }
    public static void main(String[] args) {
        System.out.print(menu());
    }
}

Verifying the Margin

To debug stripping, wrap each line in markers. This shows exactly which leading spaces survived.

public class Main {
    public static void main(String[] args) {
        String block = """
            x
              y
            """;
        for (String line : block.split("\n")) {
            System.out.println("|" + line + "|");
        }
    }
}

Quick Check

What determines how much leading (incidental) whitespace is stripped from a text block?

Recap

You learned indentation and stripping:

Incidental indentation is removed automatically
The closing """ position can set the margin
Trailing line whitespace is stripped
stripIndent(), indent(n), and strip() help at runtime
Closing quotes placement controls the final newline

Frequently asked questions

Is the “Indentation and Stripping” lesson free?

Yes — the full text of “Indentation and Stripping” is free to read here on the web, and the Java Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO.

What will I learn in “Indentation and Stripping”?

Control incidental whitespace. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Java Academy?

No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Indentation and Stripping” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Java Academy lesson?

Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

← Back to Java Academy