包装类、String转为int、正则表达式

package com.company.project.builder;

public class IntegerDemo {

public static void main(String[] args) {
Integer in = 2;
int a = in;
//Integer转换为int
System.out.println(in.intValue()+1);
//long的最大值
System.out.println(Long.MAX_VALUE);

String str = "123";
//String转为int
System.out.println(Integer.parseInt(str)+1);
//String转为double
System.out.println(Double.parseDouble(str)+1);

String str1 = "\\w+";//单词字符包括:a-z、A-Z、0-9,以及下划线
String str2 = "2232";
//正则表达式
System.out.println(str2.matches(str1));
}

}