找不到符號 - 符號：方法lastIndexOf（java.lang.String中）位置：類java.util.Scanner中

Question

我的代碼嘗試提取一個文件名來讀取包含文件名的另一個文件加載一個文件：

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)); 
} 

錯誤產生：

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 

當我試圖使用應建到Java「長度」方法產生同樣的錯誤......

Answer 1

看來readLine是Scanner類型和你試圖調用lastIndexOf()但THI方法不屬於Scanner類

Answer 2

你readLine是java.util.Scanner的......我想你在想，這是一個java.lang.String。