java 给指定类型文件加行号

java文件加行号

• 显示当前目录下的所有Java文件内容，并写入collection.txt文件中，并加入行号。

• 使用try-with-resource语句

题解

import java.io.*;

public class Test504 {
    public static void main(String[] args) {

        String outfilename = "src\Exp05\collection.txt";
        File dir = new File("src\\Exp05\\T4test");
                //lambda 表达式
        File[] files = dir.listFiles(name -> name.getName().endsWith(".java")); //此处确定文件类型

        if (files.length == 0) {

        } else {
            for (int i = 0; i < files.length; i++) {
                String line = null;
                try (FileReader freader = new FileReader(files[i]);
                     LineNumberReader lnread = new LineNumberReader(freader);
                     FileWriter fwriter = new FileWriter(outfilename, true);
                     BufferedWriter bWriter = new BufferedWriter(fwriter)) {
                    while ((line = lnread.readLine()) != null) {
                        bWriter.write("line " + lnread.getLineNumber() + ": " + line + "\t\n");

                    }
                } catch (FileNotFoundException ex) {
                    ex.printStackTrace();
                    System.out.println("找不到文件");
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }
    }
}

运行结果：

生成了collection.txt文件，内容

line 1: package Exp05.T4test;   
line 2:    
line 3: import java.util.Scanner;  
line 4:    
line 5: public class T4test {  
line 6:     public static void main(String[] args) {   
line 7:    
line 8:         System.out.println("这是一个java文件");  
line 9:     }  
line 10: }