public void testCache() throws Exception { ImageIO.setUseCache(true); assertTrue("Failed to enable cache", ImageIO.getUseCache()); ImageIO.setUseCache(false); assertFalse("Failed to disable cache", ImageIO.getUseCache()); ImageIO.setCacheDirectory(null); assertNull("Failed to set cache directory", ImageIO.getCacheDirectory()); try { ImageIO.setCacheDirectory(new File("")); fail("IllegalArgumentException expected"); } catch (IllegalArgumentException expected) { // OK } }