Xiaozhong Wang

For various reasons, an application may install a security manager. Usually it does so to guard against malicious third-party code either installed or dynamically downloaded at runtime. If the application uses RMI APIs, it's even required by a Java specification that a security manager be installed, otherwise the classloader will not download any classes from remote locations. The most convenient security manager to use is java.lang.SecurityManager. Once installed, it will work with security policy to control the security permissions granted to different protection domains. For simplicity, it will be referred to as SecurityManager for the rest of this article. The security policy is statically initialized at application start-up. For Sun's JDK, the security policy is defined in a security policy file. Naturally, this initial security policy cannot be changed at runt... (more)

Xlet: A Different Kind of Applet for J2ME

In September 2002, Sun released the J2ME Personal Profile 1.0. Unlike the MIDP, which is the core technology for Java-enabled wireless phones based on Connected Limited Device Configuration (CLDC), Personal Profile is based on the Connected Device Configuration (CDC). The CDC provides a virtual machine that includes a full Java 2 Virtual Machine feature set. Compared to CLDC, it assumes more memory and higher availability on network connections. The Personal Profile contains a full set of AWT APIs that support a graphical user interface (GUI), including support for applets and Xle... (more)

Java Developer's Journal: "@ See Javadoc"

My dear wife has just started to learn to use Java in her work and asks me a lot of questions as she begins her journey in this wonderful language. To almost all her questions my answer is the same: "See Javadoc." In addition to being a way of avoiding having to find or know the answer, it constantly surprises me what is available in the Javadoc and how useful a source of information it can be. When I began to use Java in 1998 I received the pointer of the Java API Specification, or Javadoc, from a colleague. Despite the limitations of the JDK 1.1 Javadoc style when compared to J... (more)