java split函数分割字符串

String a = "1,2,3,4,4,5";
String[] b = a.split(",");
for (int i = 0; i < b.length; i++) {
    System.out.println(i+" "+b[i]);
}
// 0 1
// 1 2
// 2 3
// 3 4
// 4 4
// 5 5

public class test {
    public static void main(String[] args) {
        String a="123.csv";
        System.out.println(a.split("\\.")[0]);
        String b="123|csv";
        System.out.println(b.split("\\|")[0]);
        String c="123,csv:321";
        System.out.println(c.split(",|:")[0]+c.split(",|:")[1]+c.split(",|:")[2]);
    }
}

//123
//123
//123csv321