{"record":{"id":"b2bb286fd144a4fd","repo":"java-native-access/jna","slug":"no-native-windows-when-headless","errorCode":null,"errorMessage":"No native windows when headless","messagePattern":"No native windows when headless","errorType":"exception","errorClass":"java.awt.HeadlessException","httpStatus":null,"severity":"error","filePath":"src/com/sun/jna/Native.java","lineNumber":2542,"sourceCode":"\n    private static class Buffers {\n        static boolean isBuffer(Class<?> cls) {\n            return Buffer.class.isAssignableFrom(cls);\n        }\n    }\n\n    /** Provides separation of JAWT functionality for the sake of J2ME\n     * ports which do not include AWT support.\n     */\n    private static class AWT {\n        static long getWindowID(Window w) throws HeadlessException {\n            return getComponentID(w);\n        }\n        // Declaring the argument as Object rather than Component avoids class not\n        // found errors on phoneME foundation profile.\n        static long getComponentID(Object o) throws HeadlessException {\n            if (GraphicsEnvironment.isHeadless()) {\n                throw new HeadlessException(\"No native windows when headless\");\n            }\n            Component c = (Component)o;\n            if (c.isLightweight()) {\n                throw new IllegalArgumentException(\"Component must be heavyweight\");\n            }\n            if (!c.isDisplayable())\n                throw new IllegalStateException(\"Component must be displayable\");\n            // On X11 VMs prior to 1.5, the window must be visible\n            if (Platform.isX11()\n                && System.getProperty(\"java.version\").startsWith(\"1.4\")) {\n                if (!c.isVisible()) {\n                    throw new IllegalStateException(\"Component must be visible\");\n                }\n            }\n            // By this point, we're certain that Toolkit.loadLibraries() has\n            // been called, thus avoiding AWT/JAWT link errors\n            // (see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6539705).\n            return Native.getWindowHandle0(c);","sourceCodeStart":2524,"sourceCodeEnd":2560,"githubUrl":"https://github.com/java-native-access/jna/blob/d036ad9781adad4b66693e8fa7098e4ac665e0a3/src/com/sun/jna/Native.java#L2524-L2560","documentation":"Native.getComponentID/getWindowID and related helpers throw java.awt.HeadlessException when the JVM runs in headless mode (java.awt.headless=true or no display). Native window handles (HWND/Window/X11 Drawable) only exist in a graphical environment, so JNA refuses up front.","triggerScenarios":"Calling Native.getComponentID/getWindowID on an AWT/Swing Component from a headless JVM: servers, CI, Docker containers without X11, or code explicitly setting -Djava.awt.headless=true.","commonSituations":"Running Swing-integration code on a headless Linux server or container; CI pipelines rendering screenshots; servlet containers that default to headless.","solutions":["Run with a display: xvfb-run, Xvfb, or a real X server on Linux; remove java.awt.headless=true if a window is genuinely needed.","Restructure code so native-window lookups only execute in graphical environments (check GraphicsEnvironment.isHeadless() first).","On Windows-only scenarios, obtain the HWND via user32 API on data you already have instead of routing through AWT."],"exampleFix":"// before\nlong hwnd = Native.getComponentID(canvas); // throws when headless\n// after\nif (GraphicsEnvironment.isHeadless()) {\n    throw new IllegalStateException(\"window handle requires a display\");\n}\nlong hwnd = Native.getComponentID(canvas);","handlingStrategy":"validation","validationCode":"if (GraphicsEnvironment.isHeadless()) {\n    throw new IllegalStateException(\"Component native IDs require a graphical environment\");\n}","typeGuard":"boolean canUseNativeWindows() {\n    return !GraphicsEnvironment.isHeadless();\n}","tryCatchPattern":"try {\n    long id = Native.getComponentID(component);\n} catch (HeadlessException e) {\n    LOG.warn(\"Headless environment; skipping native window operation\");\n    return FALLBACK_HANDLE;\n}","preventionTips":["Check GraphicsEnvironment.isHeadless() before any AWT window-handle code.","On servers/CI, run with xvfb-run when native window handles are required.","Avoid accidentally enabling java.awt.headless=true for UI-dependent code paths.","Gate window-handle features behind an environment capability check."],"tags":["jna","headless","awt","environment"],"backgroundTag":"unsupported-platform","analyzedSha":"d036ad9781adad4b66693e8fa7098e4ac665e0a3","analyzedAt":"2026-09-12T06:50:59.239Z","contentChangedAt":"2026-09-12T06:50:59.239Z","schemaVersion":2},"datasetVersion":"2026-09-14T11:17:12.474Z"}