Common package types for JAVA7JDK

Java Scanner class

Java 5 Adds the Java.util.Scanner class, which is a new utility for scanning input text. It is a combination of the previous StringTokenizer and Matcher classes. Because any data must be retrieved through a capturing group of the same pattern or by using a draw to retrieve parts of the text. You can then use a combination of regular expressions and methods to retrieve specific types of data items from the input stream. In this way, in addition to the ability to use regular expressions, the scanner class can optionally parse data for strings and basic types such as int and double. With scanner, you can write a custom parser for any text content you want to work with.

Java number and Math class

　　1. Generally, when you need to use numbers, we usually use built-in data types, such as: Byte, int, long, double, and so on.

　　2. However, in the actual development process, we often encounter situations where objects need to be used rather than built-in data types.

　　3. To solve this problem, the Java language provides a corresponding wrapper class for each built-in data type, such as.

　　4. All wrapper classes are subclasses of abstract class number.

Numbers:byte Double Float Long Integer Short

Math: The Math object is a collection of the methods that JS provides to us for operations.

Common package types for JAVA7JDK