Question

这是我的代码

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package namereader;
import java.util.*;
import java.io.*;
/**
 *
 * @author jpowell1225
 */
public class NameReader {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException{
        // TODO code application logic here
        boolean onoff = true;
        int count = 0;
        int count2 = 0;
        String first = null;
        FileWriter fw = new FileWriter("txt",true);
       
        String last = null;
        
        Scanner scan = new Scanner(System.in);
        scan.useDelimiter(" ");
        //scan.useDelimiter();
        while(onoff){
            first = scan.nextLine();
         
            if(first.equals("quit")){
                    break;
                }
            
       
                
                fw.write(first);
                FileReader fr = new FileReader("txt");
                Scanner src = new Scanner(fr);
                count = first.lastIndexOf(" "); 
                count2 =first.indexOf(" ", 2);
                System.out.println("Your name is: " + first.substring(count) + " " + first.substring(count2, count2+2) + ". " + first.substring(0, count2));
 
        }
        fw.close();
        scan.close();
        
         
    }
    
}

虽然它确实正确输出了输入的名称（从First Middle Last切换到Last First Middle Initial），但它确实正确地创建了一个名为“txt”的文件，每当我打开文件时它都是空的。

我需要能够在文件“txt”中添加多个输入。 TIA

Answer 1

您忘记了flush()输出流

fw.flush();//flush it before close it.
fw.close();

您也可以使用try(<<Closable>>){}让Java自动关闭（FileWriter）。

修改
try(<<closable_0>>;<<closable_1>>;...){}是一个自java1.7以来的新方案，它用于让jvm在块之后自动关闭closable对象。在你的代码中它可能是这样的。

try(Scanner scan = new Scanner(System.in);FileWriter fw = new FileWriter("txt",true);){ //using the objects }//jre will closes both :scan and :fw objects automatically

我需要用java编写一个文件

1 个答案: