Question

我正在使用OpenCsv访问我希望排序的fie，然后写回另一个文件名。我有问题排序列表。谢谢。

我试图按第1列和第2列对csv文件进行排序。

 CSVReader reader = new CSVReader(new FileReader("d:\\temp\\data1.csv"), ',', '"', 1);

 //Read all rows at once
 List<String[]> allRows = reader.readAll();

 //Read CSV line by line and use the string array as you want
 for(String[] row : allRows){
    System.out.println(Arrays.toString(row));
 }

 *Arrays.sort(allRows.toArray());*

 CSVWriter writer = new CSVWriter(new FileWriter("d:\\temp\\data1sorted.csv"));
 writer.writeAll(allRows);

 //close the writer
 writer.close();

运行此代码时出现以下错误：

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.lang.Comparable
    at java.util.ComparableTimSort.countRunAndMakeAscending(Unknown Source)
    at java.util.ComparableTimSort.sort(Unknown Source)
    at java.util.ComparableTimSort.sort(Unknown Source)
    at java.util.Arrays.sort(Unknown Source)
    at CompareCsv.main(CompareCsv.java:31)

Answer 1

这对你有帮助吗？

public static void main(String args[]) {
            ArrayList<String> animalList = new ArrayList<String>();

        animalList.add("Dog");
        animalList.add("Cat");
        animalList.add("Snake");
        animalList.add("Bison");

        System.out.println("Before Sorting:");
        for (String tmpStr : animalList) {
            System.out.println(tmpStr);
        }

        // sorting
        Collections.sort(animalList);

        System.out.println("After Sorting:");
        for (String tmpStr : animalList) {
            System.out.println(tmpStr);
        }
    }

Answer 2

您可以为您的目的实施比较器并使用： https://docs.oracle.com/javase/7/docs/api/java/util/Collections.html#sort(java.util.List,%20java.util.Comparator)

Answer 3

目前尚不清楚您是希望行内排序还是相互比较。假设两者;

for(String[] row : allRows)
{
   Arrays.sort(row);
}

Collections.sort(allRows, new Comparator()
{
    @Override
    public int compare(Object o1, Object o2)
    {
        String[] a = (String[])o1;
        String[] b = (String[])o2;
        return a[0].compareTo(b[0]); //you'll probably want some additional checking here.
    }
});

如何在java中对此数组列表进行排序

3 个答案: