13-03 java basic type wrapper class overview, integer class, character

Overview of basic types and packaging classes

The advantage of encapsulating basic data types as objects is that more functional methods can be defined in the object to manipulate the data. One of the common operations: used for conversion between basic data type and string. Byte, short, integer, long, float, double, character, Boolean corresponding to basic type and wrapper class

Integer class

In order to allow more operations on the data of basic types, Java provides corresponding wrapper class types for each basic type

Construction method of integer

Conversion between string and int

Operation of binary conversion of integer

New features of jdk5 -- automatic packing and automatic unpacking

-Data buffer pool problem between 128 and 127

Character

Character 类在对象中包装一个基本类型 char 的值

Character 类，常见方法。

确定字符的类别（小写字母，数字，等等），并将字符从大写转换成小写

Count the occurrence times of uppercase, lowercase and numeric characters in a string