Tokens, Literals & Delimiters:
- Missing semicolon after statement
- Missing opening curly brace
- Extraneous closing curly brace
- Missing closing curly brace
- Mismatched parentheses
- Mismatched brackets
- Unterminated or unquoted literal/comment
- Invalid escape in string literal
- Illegal character
- Invalid numeric literal
Expressions & Operators:
- Invalid assignment target
- Missing or misplaced separator (operator, dot, comma)
- Wrong operand types in operators
- Using math-notation as operator
- Using assignment instead of comparison in conditions
- Using and, or, not instead of &&, ||, !
- Malformed expression or statement (unspecified)
Names & Scope:
- Using reserved words as identifiers
- Case-sensitivity errors
- Misspelled variable names
- Misspelled keywords
- Misspelled method names
- Misspelled class names
- Using undeclared variable identifier
- Calling undeclared method
- Out-of-scope variable identifier
- Member used as method or field
Declarations & Initialization:
- Invalid variable declaration
- Incorrect initialization syntax
- Duplicate declaration (variable/method/class)
- Using uninitialized variable
Types & Arrays:
- Incompatible type in assignment
- Incompatible type in return statement
- Invalid type casts
- Char and string mismatch
- Using primitive type as generic type argument
- Member access on a primitive value
- Array declaration or creation syntax
- Indexing a non-array or invalid array access
Methods & Constructors:
- Incorrect main method signature
- Invalid method declaration or override
- Calling method with wrong number of arguments
- Calling method with wrong type of arguments
- Missing return in method
- Invalid object creation (constructor or abstract class)
Classes, Objects & Access:
- Missing class definition
- Multiple public classes in one file
- Statement outside a method
- Illegal member access (static context or visibility)
- Invalid or misplaced modifier
Control Flow & Exceptions:
- While/do-while header syntax errors
- For header syntax errors
- Conditional statement errors (if/else/switch)
- Misplaced or unreachable control flow
- Exception handling errors (try/catch/throws)
Imports & Packages:
- Missing import
- Missing identifier after import
- Invalid import or package declaration
Input Quality & Fallback:
- Non-Java Code
- Unclassifiable