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));    }}