java - 无法实例化类型 Scanner

Question

我是 Java 新手。我想通过扫描仪读取输入。我收到错误，因为无法“实例化类型扫描仪”。

import java.util.*;  
import java.io.File;  

public class Factors {  

//string declaration  
static String filename;  

public static void main(String args[]){  
    //scanner initialization, needs to be done in every program that reads from user  
    Scanner input = new Scanner(System.in);  
    int caseIndex=0;  

    //prompts user for filename  
    System.out.println("Please enter the name of the file you would like to read from.");  
    filename = input.nextString();  

    //checks if filename exists  
    if(input.exists())  
        System.out.println(inp.getName() + "exists!");  
    else  
        System.out.println("File name does not exist!");  



 }  

}

我不明白我在哪里缺乏。请帮忙。先感谢您。

Answer 1

Scanner没有方法nextString()和exists()方法。我认为您的要求是检查该文件是否存在。像这样做：

    import java.util.*;  
    import java.io.File;  

    public class Factors 
    { 
        static String filename;  
     public static void main(String[] args) 
     {
            //scanner initialization, needs to be done in every program that reads from user  
            Scanner input = new Scanner(System.in);  
            int caseIndex=0;  

            //prompts user for filename  
            System.out.println("Please enter the name of the file you would like to read from.");  
            filename = input.nextLine();  
            File file=new File(filename);
            //checks if filename exists  
            if(file.exists())  
                System.out.println(file.getName() + "exists!");  
            else  
                System.out.println("File name does not exist!");  
    }

}