### Question:
JavaHomeUtil { public static File getToolsJar() { if (!JavaVersionUtil.isLessThanJava9()) { return null; } String javaHomeDir = getJavaHomeDir(); File toolsJar = new File(javaHomeDir, "lib/tools.jar"); if (!toolsJar.exists()) { toolsJar = new File(javaHomeDir, "../lib/tools.jar"); } if (!toolsJar.exists()) { toolsJar = new File("../../lib/tools.jar"); } if (!toolsJar.exists()) { throw new IllegalArgumentException("Can not find tools.jar under java.home"); } return toolsJar; }  static String getJavaHomeDir(); static File getToolsJar();  }### Answer:
@Test void getToolsJar() { System.out.println(JavaHomeUtil.getToolsJar()); }