java - 在Java中逐行读取文本文件

Question

如何逐行读取文本文件中的内容？当我尝试输出内容时，换行符似乎被忽略了。

public class ReadFile {
    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        String str= "";

        //Reading content from file
        Scanner in = new Scanner(new FileReader("text.txt"));
        while(in.hasNextLine()){
            str = str + in.nextLine();
            str.concat("\n");      //Not working!!!!!!!!!!!
        }

        in.close();

        //Writing content to another file
        PrintWriter out = new PrintWriter(new FileWriter("output.txt"));
        out.println(str);
        out.close();
    }
}

Answer 1

您在以下行中犯了错误:

str.concat("\n"); 

更新如下:

str = str.concat("\n"); 

我正在提供更新的程序。

public class ReadFile {

    public static void main(String[] args) throws IOException {
        try (PrintWriter out = new PrintWriter(new FileWriter("output.txt"));
                Scanner in = new Scanner(new FileReader("text.txt"));) {
            while (in.hasNextLine()) {
                out.println(in.nextLine());
            }
        }
    }
}