Java的String.matches不区分大小写正则表达式匹配示例

需求：输入的cmd符合create，listall，delete三种形式，不用区分大小写

写成函数：

    public static boolean isAllowed3Cmd(String cmd) {
        return cmd.matches("^(?i)(create|delete|listall)$");
    }

正则式分析：

^...$:从字符串头到尾全部符合模式

？i:不区分大小写

create|delete|listall：三选一

完整测试代码：

public class StringMatchesTest {
    public static void main(String[] args) {
        String[] arr= {"creat","create","Create","DELETE","LISTall","list","creat","del","listalllistall","deletecreate"};
        for(String cmd:arr) {
            System.out.println(String.format("String:%s %s pattern:%s",cmd,isAllowed3Cmd(cmd)?"matches":"dosen't match","'^(?i)(create|delete|listall)$'"));
        }
    }

    public static boolean isAllowed3Cmd(String cmd) {
        return cmd.matches("^(?i)(create|delete|listall)$");
    }
}

输出：

String:creat dosen't match pattern:'^(?i)(create|delete|listall)$'
String:create matches pattern:'^(?i)(create|delete|listall)$'
String:Create matches pattern:'^(?i)(create|delete|listall)$'
String:DELETE matches pattern:'^(?i)(create|delete|listall)$'
String:LISTall matches pattern:'^(?i)(create|delete|listall)$'
String:list dosen't match pattern:'^(?i)(create|delete|listall)$'
String:creat dosen't match pattern:'^(?i)(create|delete|listall)$'
String:del dosen't match pattern:'^(?i)(create|delete|listall)$'
String:listalllistall dosen't match pattern:'^(?i)(create|delete|listall)$'
String:deletecreate dosen't match pattern:'^(?i)(create|delete|listall)$'

--2020年3月30日--