{"record":{"id":"c9ed5d539531f944","repo":"Blankj/AndroidUtilCode","slug":"u-can-t-instantiate-me-c9ed5d","errorCode":null,"errorMessage":"u can't instantiate me...","messagePattern":"u can't instantiate me\\.\\.\\.","errorType":"exception","errorClass":"UnsupportedOperationException","httpStatus":null,"severity":"info","filePath":"lib/utilcode/src/main/java/com/blankj/utilcode/util/CrashUtils.java","lineNumber":26,"sourceCode":"import java.util.Map;\n\n/**\n * <pre>\n *     author: Blankj\n *     blog  : http://blankj.com\n *     time  : 2016/09/27\n *     desc  : utils about crash\n * </pre>\n */\npublic final class CrashUtils {\n\n    private static final String FILE_SEP = System.getProperty(\"file.separator\");\n\n    private static final UncaughtExceptionHandler DEFAULT_UNCAUGHT_EXCEPTION_HANDLER =\n        Thread.getDefaultUncaughtExceptionHandler();\n\n    private CrashUtils() {\n        throw new UnsupportedOperationException(\"u can't instantiate me...\");\n    }\n\n    /**\n     * Initialization.\n     */\n    public static void init() {\n        init(\"\");\n    }\n\n    /**\n     * Initialization\n     *\n     * @param crashDir The directory of saving crash information.\n     */\n    public static void init(@NonNull final File crashDir) {\n        init(crashDir.getAbsolutePath(), null);\n    }\n","sourceCodeStart":8,"sourceCodeEnd":44,"githubUrl":"https://github.com/Blankj/AndroidUtilCode/blob/7b4caf9e5440046b3fefb63b6b6e2ead7ebaf809/lib/utilcode/src/main/java/com/blankj/utilcode/util/CrashUtils.java#L8-L44","documentation":"CrashUtils is a final utility class that installs an UncaughtExceptionHandler to log crashes to disk; its private constructor throws UnsupportedOperationException(\"u can't instantiate me...\"). It is used entirely through static init/handler methods, so no instance is required and the constructor only blocks instantiation, matching the library-wide *Utils convention.","triggerScenarios":"Reflective instantiation (getDeclaredConstructor().newInstance() with setAccessible) or a framework that new-ups classes by Class reference. A normal `new CrashUtils()` is rejected at compile time because the constructor is private.","commonSituations":"Coverage tooling that instantiates every class; DI or service-loader-style scans that try to construct discovered classes; a developer who believes init() must be called on an instance; mutation testing that targets constructors.","solutions":["Call the static entry point directly: CrashUtils.init() and read its callbacks statically — never construct an instance.","Configure any reflective instantiation tool to skip final classes or specifically exclude CrashUtils.","For a contract test, assert UnsupportedOperationException is thrown rather than using the produced instance."],"exampleFix":"// before (reflection)\nCrashUtils cu = CrashUtils.class.getDeclaredConstructor().newInstance();\n\n// after\nCrashUtils.init();","handlingStrategy":"validation","validationCode":"// Never construct CrashUtils; it is static-only.\nif (clazz == CrashUtils.class || Modifier.isFinal(clazz.getModifiers())) {\n    // skip instantiation; call CrashUtils.init() statically\n}","typeGuard":"if (clazz.getName().endsWith(\"Utils\") && Modifier.isFinal(clazz.getModifiers())) {\n    // static-only; do not newInstance()\n}","tryCatchPattern":"try {\n    Constructor<?> c = CrashUtils.class.getDeclaredConstructor();\n    c.setAccessible(true);\n    c.newInstance();\n} catch (UnsupportedOperationException e) {\n    // expected; use CrashUtils.init() / static API\n}","preventionTips":["CrashUtils is static-only — never instantiate it via `new` or reflection.","Exclude final 'Utils' classes from coverage/DI/mutation tools that construct everything.","Call CrashUtils.init() once at app start instead of holding an instance."],"tags":["utility-class","instantiation","design-pattern","reflection","crash"],"backgroundTag":null,"analyzedSha":"7b4caf9e5440046b3fefb63b6b6e2ead7ebaf809","analyzedAt":"2026-08-14T02:26:54.956Z","schemaVersion":2},"datasetVersion":"2026-08-14T05:17:29.042Z"}