Question

我正在尝试对文本文件进行排序，该文件由制表符分隔并尝试按第三个字段className排序。然后我将在表格中显示它。我写了以下部分，但没有正确排序。关于我哪里出错的任何想法？

    public void sortFile(){
    BufferedReader reader = null; 
    BufferedWriter writer = null;

    //Create an ArrayList object to hold the lines of input file
    ArrayList<String> lines = new ArrayList<>();


    try{
        //Creating BufferedReader object to read the input file
        reader = new BufferedReader(new FileReader("pupilInfo.txt"));
        //Reading all the lines of input file one by one and adding them into ArrayList
        String currentLine = reader.readLine();
        while (currentLine != null){
            lines.add(currentLine);
            currentLine = reader.readLine();
        } 


            Collections.sort(lines, (String s1, String s2) -> {
            s1 = lines.get(0);
            s2 = lines.get(1);
            String [] line1 = s1.split("\t");
            String [] line2 = s2.split("\t");
            String classNameLine1 = line1[2];
            String classNameLine2 = line2[2];
            System.out.println("classname1=" + classNameLine1);
            System.out.println("classname2=" + classNameLine2);
            int sComp = classNameLine1.compareTo(classNameLine2);
            return sComp;
        });
        //Creating BufferedWriter object to write into output temp file
        writer = new BufferedWriter(new FileWriter("pupilSortTemp.txt"));
        //Writing sorted lines into output file
        for (String line : lines){
            writer.write(line);
            writer.newLine();
        }            
    }catch (IOException e){
    }
    finally{
    //Closing the resources
        try{
            if (reader != null){
                reader.close();
            }
            if(writer != null){
                writer.close();
            }
        }catch (IOException e){
        }
    }  

}

Answer 1

我尝试使用＆＃34;比较器＆＃34;。为简单起见，我的源文件如下

pippo;pluto;paperino
casa;terra;cortile
primo;secondo;terzo

Comparator<String> comparator = new Comparator<String>() {
                @Override
                public int compare(String o1, String o2) {
                    return o1.split(";")[2].compareTo(o2.split(";")[2]);

                }
            };

            lines.sort(comparator);

最终输出

[casa;terra;cortile, pippo;pluto;paperino, primo;secondo;terzo]

按第三栏排序！

比较使用Collections.sort

1 个答案: