human-readable-errors

{ "language": "java", "framework": "spring", "errors": [ { "type": "NullPointerException", "code": "SPR001", "error": "Null Object Reference", "severity": "High", "description": "Occurs when attempting to use a reference variable that points to a null object", "cause": [ "Uninitialized object reference", "Incorrect object initialization", "Method returning null unexpectedly" ], "solution": [ "Use null checks before accessing object methods", "Initialize objects before use", "Use Optional<> for potentially null values", "Use Objects.requireNonNull() for mandatory references" ], "tags": ["runtime-error", "object-handling", "nullability"], "examples": [ { "code": "String str = null;\nint length = str.length(); // Throws NullPointerException", "output": "Exception in thread \"main\" java.lang.NullPointerException" }, { "code": "if (str != null) {\n int length = str.length(); // Safe approach\n}", "output": "No exception" } ], "links": [ "https://docs.oracle.com/javase/8/docs/api/java/lang/NullPointerException.html" ] }, { "type": "ClassCastException", "code": "SPR002", "error": "Incompatible Type Conversion", "severity": "High", "description": "Occurs when attempting to cast an object to a class it is not an instance of", "cause": [ "Incorrect type casting", "Unexpected object type in collection", "Generics type mismatch" ], "solution": [ "Use instanceof check before casting", "Implement proper type checking", "Use generics with type parameters", "Utilize type-safe collections" ], "tags": ["runtime-error", "type-casting", "type-safety"], "examples": [ { "code": "Object obj = \"Hello\";\nInteger num = (Integer) obj; // Throws ClassCastException", "output": "Exception in thread \"main\" java.lang.ClassCastException" }, { "code": "if (obj instanceof Integer) {\n Integer num = (Integer) obj; // Safe casting\n}", "output": "No exception" } ], "links": [ "https://docs.oracle.com/javase/8/docs/api/java/lang/ClassCastException.html" ] }, { "type": "IllegalArgumentException", "code": "SPR003", "error": "Invalid Method Argument", "severity": "Medium", "description": "Thrown when a method receives an argument that is not appropriate for the method's purpose", "cause": [ "Passing null to a method expecting a non-null value", "Providing out-of-range values", "Incorrect argument type" ], "solution": [ "Validate method arguments before passing", "Use argument validation annotations", "Implement input validation logic", "Use @Valid annotation for bean validation" ], "tags": ["validation-error", "method-invocation", "input-checking"], "examples": [ { "code": "public void processAge(int age) {\n if (age < 0) throw new IllegalArgumentException(\"Age cannot be negative\");\n}", "output": "Exception in thread \"main\" java.lang.IllegalArgumentException: Age cannot be negative" } ], "links": [ "https://docs.oracle.com/javase/8/docs/api/java/lang/IllegalArgumentException.html" ] }, { "type": "NoSuchBeanDefinitionException", "code": "SPR004", "error": "Spring Bean Configuration Error", "severity": "High", "description": "Occurs when attempting to access a bean that is not defined in the Spring application context", "cause": [ "Missing bean configuration", "Incorrect bean name or type", "Misconfigured component scanning", "Dependency not properly defined" ], "solution": [ "Verify @Component, @Service, @Repository annotations", "Check component scanning packages", "Use @Autowired with @Qualifier if needed", "Ensure correct bean configuration in XML or Java config" ], "tags": ["spring-framework", "dependency-injection", "configuration"], "examples": [ { "code": "@Autowired\nprivate UserService userService; // If UserService is not defined\n", "output": "Exception: org.springframework.beans.factory.NoSuchBeanDefinitionException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/NoSuchBeanDefinitionException.html" ] }, { "type": "DataIntegrityViolationException", "code": "SPR005", "error": "Database Constraint Violation", "severity": "High", "description": "Thrown when an attempt to insert or update data violates database integrity constraints", "cause": [ "Unique constraint violation", "Foreign key constraint failure", "Not-null constraint violation", "Data type mismatch" ], "solution": [ "Implement proper data validation before database operations", "Use @UniqueConstraint for entity constraints", "Handle database-specific exceptions", "Use transaction management" ], "tags": ["database-error", "jpa", "hibernate", "data-persistence"], "examples": [ { "code": "@Entity\npublic class User {\n @Column(unique = true)\n private String username;\n}", "output": "Exception: org.springframework.dao.DataIntegrityViolationException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/dao/DataIntegrityViolationException.html" ] }, { "type": "MethodArgumentNotValidException", "code": "SPR006", "error": "Validation Failure", "severity": "Medium", "description": "Occurs when bean validation (JSR-303) fails for method arguments", "cause": [ "Bean validation constraints not met", "Invalid input data", "Missing required fields", "Value out of specified range" ], "solution": [ "Use @Valid annotation on method parameters", "Add validation annotations like @NotNull, @Size, @Pattern", "Create custom validation constraints", "Implement global exception handling" ], "tags": ["validation", "bean-validation", "input-validation"], "examples": [ { "code": "public void createUser(@Valid @RequestBody UserDTO user) { ... }\n\nclass UserDTO {\n @NotNull\n @Size(min = 3, max = 50)\n private String username;\n}", "output": "Exception: org.springframework.web.bind.MethodArgumentNotValidException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/MethodArgumentNotValidException.html" ] }, { "type": "TransactionSystemException", "code": "SPR007", "error": "Transaction Management Failure", "severity": "High", "description": "Occurs when a problem arises during transaction management", "cause": [ "Nested transaction errors", "Database connection issues", "Incomplete transaction rollback", "Concurrent transaction conflicts" ], "solution": [ "Use @Transactional annotation carefully", "Implement proper exception handling", "Configure transaction management settings", "Use appropriate isolation levels" ], "tags": ["transaction", "database", "spring-data"], "examples": [ { "code": "@Transactional\npublic void performComplexOperation() { ... }", "output": "Exception: org.springframework.transaction.TransactionSystemException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/transaction/TransactionSystemException.html" ] }, { "type": "BeanCreationException", "code": "SPR008", "error": "Spring Bean Initialization Failure", "severity": "High", "description": "Occurs when Spring fails to create a bean during application context initialization", "cause": [ "Constructor injection errors", "Dependency cycle", "Missing required dependencies", "Incorrect bean configuration" ], "solution": [ "Resolve circular dependencies", "Check constructor and setter injection", "Verify @Autowired and @Inject usage", "Use @Lazy or provider injection if needed" ], "tags": ["spring-framework", "bean-creation", "dependency-injection"], "examples": [ { "code": "@Component\npublic class CircularDependencyBean {\n @Autowired\n private CircularDependencyBean self;\n}", "output": "Exception: org.springframework.beans.factory.BeanCreationException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/BeanCreationException.html" ] }, { "type": "HttpMediaTypeNotSupportedException", "code": "SPR009", "error": "Unsupported Media Type", "severity": "Medium", "description": "Thrown when the request content type is not supported by the REST endpoint", "cause": [ "Incorrect Content-Type header", "Unsupported media type in REST API", "Mismatch between client and server content type", "Missing media type configuration" ], "solution": [ "Specify correct Content-Type header", "Use @RequestMapping with produces/consumes attributes", "Configure media type converters", "Handle media type negotiation explicitly" ], "tags": ["rest-api", "http", "content-negotiation"], "examples": [ { "code": "@PostMapping(consumes = MediaType.APPLICATION_JSON_VALUE)\npublic void createResource(@RequestBody MyResource resource) { ... }", "output": "Exception: org.springframework.web.HttpMediaTypeNotSupportedException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/HttpMediaTypeNotSupportedException.html" ] }, { "type": "ResourceAccessException", "code": "SPR010", "error": "Resource Access Failure", "severity": "Medium", "description": "Occurs when there's an I/O problem accessing an external resource", "cause": [ "Network connectivity issues", "Timeout during resource access", "Connection refused", "SSL/security-related access problems" ], "solution": [ "Configure proper timeout settings", "Implement robust error handling", "Use circuit breaker patterns", "Validate external resource configurations" ], "tags": ["network", "resource-access", "connectivity"], "examples": [ { "code": "RestTemplate restTemplate = new RestTemplate();\nrestTemplate.getForObject(\"http://external-api.com/data\", String.class);", "output": "Exception: org.springframework.web.client.ResourceAccessException" } ], "links": [ "https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/client/ResourceAccessException.html" ] } ] }