1.StringUtils

isEmpty isBlank区别

public class Test1 {
    public static void main(String[] args) {
        boolean empty = StringUtils.isEmpty("");
        boolean empty1 = StringUtils.isEmpty(" ");
        boolean empty2 = StringUtils.isEmpty(null);
        boolean blank = StringUtils.isBlank("");
        boolean blank1 = StringUtils.isBlank(" ");
        boolean blank2 = StringUtils.isBlank(null);
        System.out.println(empty);
        System.out.println(empty1);//false
        System.out.println(empty2);
        System.out.println(blank);
        System.out.println(blank1);
        System.out.println(blank2);
        //其他都为true
    }
}

trim strip deleteWhitespace 处理字符串

public class Test2 {
    public static void main(String[] args) {
        String trim = StringUtils.trim("    as  ");
        System.out.println(trim);//as
        String strip = StringUtils.strip(" abc ", null);
        System.out.println(strip);//abc
        String strip1 = StringUtils.strip(" ABCD", "DB");
        System.out.println(strip1);//  ABC
        String strip2 = StringUtils.strip(" ABCD", "DBC");
        System.out.println(strip2);// A
        //去除字符串中的空格
        String s = StringUtils.deleteWhitespace("  mm  mm  dd  ");
        System.out.println(s);//mmmmdd
    }
}

字符串比对方法，是比较实用的方法之一，两个比较的字符串都能为空，不会报空指针异常

public class Test3 {
    public static void main(String[] args) {
        boolean equals = StringUtils.equals(null, "");
        boolean equals1 = StringUtils.equals(" ", "  ");
        boolean equals2 = StringUtils.equals(" ", " ");
        System.out.println(equals);//false
        System.out.println(equals1);//false
        System.out.println(equals2);//true
        //忽视大小写
        boolean b = StringUtils.endsWithIgnoreCase("A", "a");
        System.out.println(b);//true

    }
}