CodeQL documentation

Missing format argument

ID: java/missing-format-argument
Kind: problem
Severity: error
Precision: very-high
Tags:
   - correctness
   - external/cwe/cwe-685
Query suites:
   - java-security-and-quality.qls

Click to see the query in the CodeQL repository

When formatting strings using printf-style format strings, one must ensure that the number of supplied arguments matches the number of arguments referenced by the format string. Additional arguments will be thrown away silently, which may not be the intended behavior, and too few arguments will cause an IllegalFormatException.

Format strings are used by the format method on the classes String, Formatter, Console, PrintWriter, and PrintStream. Several of these classes also supply the method alias printf. The class Console has two additional methods, readLine and readPassword, that also use format strings.

Recommendation

Supply the correct number of arguments to the format method, or change the format string to use the correct arguments.

Example

The following example supplies only one argument to be formatted, but the format string refers to two arguments, so this will throw an IllegalFormatException.

System.out.format("First string: %s Second string: %s", "Hello world");

References