doocs/leetcode · error · IllegalArgumentException

Invalid char:

Error message

Invalid char: 

What it means

This is the Java Zuma Game encode() switch inside the Chinese README for LeetCode 488. Characters are mapped R->0x1, G->0x2, B->0x3, W->0x4, Y->0x5, space->0x0; the default branch throws IllegalArgumentException naming the offending character. It documents that any input outside [RGBYW ] is a programming error, not a runtime condition to recover from.

Source

Thrown at solution/0400-0499/0488.Zuma Game/README.md:301

        }

        long stateBits = 0;
        for (char ch : stateChars) {
            stateBits = (stateBits << 3) | Zuma.encode(ch);
        }
        return stateBits;
    }

    private static long encode(char ch) {
        return switch (ch) {
            case 'R' -> 0x1;
            case 'G' -> 0x2;
            case 'B' -> 0x3;
            case 'W' -> 0x4;
            case 'Y' -> 0x5;
            case ' ' -> 0x0;
            default  ->
                throw new IllegalArgumentException("Invalid char: " + ch);
        };
    }
}
```

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View on GitHub (pinned to f84f361dc4)

Solutions

1. Normalize input first: s = s.trim().toUpperCase() and filter to [RGBYW]
2. Extend the switch when adding new colors to the game
3. Validate with a character whitelist loop or regex before encoding
4. Check the exception message — it prints the exact char that failed

Example fix

// before
encode("RgB"); // throws Invalid char: g

// after
encode("RgB".toUpperCase()); // ok

String s2 = s.trim().toUpperCase();
if (!s2.matches("[RGBYW ]*")) throw new IllegalArgumentException("Invalid char in: " + s2);

private static boolean isValidBoardChar(char c) { return "RGBYW ".indexOf(c) >= 0; }

try { encode(input); } catch (IllegalArgumentException e) { /* message names the bad char; sanitize input and retry */ }

When it happens

Trigger: Compiling the README snippet and calling encode with lowercase letters, punctuation, or whitespace other than plain space (tabs, CR/LF from file reads).

Common situations: Following the tutorial with hand-typed input that includes a typo or wrong case; reading boards from files without trim(); extending the solution to more colors but forgetting the encoder; mixed full-width characters from CJK input methods.

Related errors

• Invalid char:
• Invalid char:
• Can not divide by 0
• Not Equal
• Equal

AI-assisted analysis of doocs/leetcode@f84f361dc4 (2026-08-27). Data as JSON: /api/errors/e8ff76e35e2bbff7. Report an issue: GitHub.