Java Core Technology (8th Edition) Learning Notes _ Overview __java

1th Chapter Java Programming Overview 1. About Java Java
Java is a complete platform with a large library that contains a lot of reusable code and an execution environment that provides services such as security, portability across the operating system, and automatic garbage collection. . NET platform also relies on virtual machine dependencies for specific implementations
The Java specification does not have a "dependency-specific implementation", unlike C and + +. The size of the base data type and the algorithms are clearly described. For example, an int in Java is always 32 bits. Applet
Running a Java program in a Web page is called an applet. Today, most Web pages use JavaScript or flash directly when you need to display dynamic effects in a browser. Running Speed
Early Java was an interpretive type. Now, in addition to the "micro" platform such as mobile phones, Java virtual machines use an instant compiler, so the Java-written "hot" code to run the same speed as C + +.
Java has some extra overhead that C + + does not have. Virtual machines have a slower startup time, and the Java GUI is slower than the local GUI because they take a platform-independent approach to drawing. JavaScript is a scripting language that is used in Web pages.