找不到符号—符号：方法lastIndexOf（java.lang.String）位置：类java.util.Scanner

Question

我的代码尝试从读取包含文件名的另一个文件中提取文件名以加载文件：

public static void main(String[] args) throws IOException
{
    Scanner scan;
    String transFilename;
    String filename;

    scan = new Scanner(System.in);
    System.out.print("Enter the name of your transaction file please (include .txt extension): ");
    transFilename = scan.nextLine();
    scan = new Scanner(new FileReader(transFilename));

    filename = readLine.next(2,readLine.lastIndexOf(""));    
    Scanner input = new Scanner( new FileReader(filename));   
}

错误产生：

blah.java:72: cannot find symbol
symbol  : method lastIndexOf(java.lang.String)
location: class java.util.Scanner
            filename = readLine.next(2,readLine.lastIndexOf(""));    
                                               ^
1 error

当我尝试使用应该内置到Java中的“ .length”方法时，会生成相同的错误...

Answer 1

似乎readLine是Scanner类型，并且您正在尝试调用lastIndexOf()但此方法不属于Scanner类

Answer 2

您的readLine是java.util.Scanner ...我猜您在想这是java.lang.String。