code-generation

Code Generation Formatting

Java code generators that build source via string concatenation need // @formatter:off / // @formatter:on guards. Without them, IntelliJ's formatter splits concatenation chains and breaks the correspondence between Java source lines and generated output lines.

The rule

Each \n-terminated line of generated output occupies exactly one Java source line. A Java line break occurs only where the template has a \n.

Bad (auto-formatted):

setterBody = ""
    + "            domainObject.get"
    + propNameUpper
    + "().clear();\n"
    + "            return;\n";

Good:

// @formatter:off
setterBody = ""
        + "            domainObject.get" + propNameUpper + "().clear();\n"
        + "            return;\n";
// @formatter:on

Finding violations

Look for concatenation blocks containing \n literals that are not inside // @formatter:off. Typical shapes:

• Multi-line + chains with template variables split from their surrounding string literals.
• .collect() lambdas whose single-line template was broken across lines.
• return ( "" + ... ) wrapped in parentheses instead of return "" + ....

Fixing

Wrap the block in // @formatter:off and // @formatter:on, and collapse each \n-terminated segment onto one line with + continuation. A .collect() lambda with a single-line template goes entirely on one line. When the strings contain valid Java source, add // language=JAVA after // @formatter:off for IntelliJ language injection.

Match the indentation of existing @formatter:off blocks in the file. The usual pattern is tabs with aligned +:

		// @formatter:off
		// language=JAVA
		return ""
				+ "package " + packageName + ";\n"
				+ "\n"
				+ "public class " + className + "\n"
				+ "{\n"
				+ "}\n";
		// @formatter:on

		// @formatter:off
		String fields = properties
			.collect((p) -> "    public final " + this.getType(p) + " " + p.getName() + ";\n")
			.makeString("");
		// @formatter:on