split（）方法：指定字符（串）或正则去分割某个字符串，结果以字符串数组形式返回；

给出几种代码及结果：
1、结果为0

public class TestSpit {
    public static void main(String[] args) {
        String str = "@";
        System.out.println(str.split("@"
        ).length);
    }
}

"E:\JAVA\IntelliJ IDEA 2019.3.2\jbr\bin\java.exe" "-javaagent:E:\JAVA\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar=50176:E:\JAVA\IntelliJ IDEA 2019.3.2\bin" -Dfile.encoding=UTF-8 -classpath E:\JAVA\project\day06-code\out\production\day06-code com.lg.demo11.TestSpit
0

Process finished with exit code 0

2、结果为1

public class TestSpit {
    public static void main(String[] args) {
        String str = "";
        System.out.println(str.split("@"
        ).length);
    }
}

原字符串中不包含@

"E:\JAVA\IntelliJ IDEA 2019.3.2\jbr\bin\java.exe" "-javaagent:E:\JAVA\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar=50461:E:\JAVA\IntelliJ IDEA 2019.3.2\bin" -Dfile.encoding=UTF-8 -classpath E:\JAVA\project\day06-code\out\production\day06-code com.lg.demo11.TestSpit
1

Process finished with exit code 0

3、结果为2

public class TestSpit {
    public static void main(String[] args) {
        String str = "123@123";
        System.out.println(str.split("@"
        ).length);
    }
}

"E:\JAVA\IntelliJ IDEA 2019.3.2\jbr\bin\java.exe" "-javaagent:E:\JAVA\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar=50507:E:\JAVA\IntelliJ IDEA 2019.3.2\bin" -Dfile.encoding=UTF-8 -classpath E:\JAVA\project\day06-code\out\production\day06-code com.lg.demo11.TestSpit
2

Process finished with exit code 0

4、结果为3

public class TestSpit {
    public static void main(String[] args) {
        String str = "123@123@123";
        System.out.println(str.split("@"
        ).length);
    }
}

"E:\JAVA\IntelliJ IDEA 2019.3.2\jbr\bin\java.exe" "-javaagent:E:\JAVA\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar=50544:E:\JAVA\IntelliJ IDEA 2019.3.2\bin" -Dfile.encoding=UTF-8 -classpath E:\JAVA\project\day06-code\out\production\day06-code com.lg.demo11.TestSpit
3

Process finished with exit code 0