具有多个字段的Collections.sort

Question

我有一个包含三个字段（所有字符串类型）的“报表”对象列表-

ReportKey

StudentNumber

School

我有一个排序代码，就像-

Collections.sort(reportList, new Comparator<Report>() {

@Override

public int compare(final Report record1, final Report record2) {

      return (record1.getReportKey() + record1.getStudentNumber() + record1.getSchool())                      

        .compareTo(record2.getReportKey() + record2.getStudentNumber() + record2.getSchool());

      }

});

由于某种原因，我没有排序顺序。一个建议在字段之间插入空格，但是为什么呢？

您认为代码有什么问题吗？

Answer 1

您认为代码有什么问题吗？是。为什么在比较它们之前将三个字段加在一起？我可能会做这样的事情：（假设字段按您希望排序的顺序排列）@Override public int compare(final Report record1, final Report record2) {&nbsp; &nbsp; int c;&nbsp; &nbsp; c = record1.getReportKey().compareTo(record2.getReportKey());&nbsp; &nbsp; if (c == 0)&nbsp; &nbsp; &nbsp; &nbsp;c = record1.getStudentNumber().compareTo(record2.getStudentNumber());&nbsp; &nbsp; if (c == 0)&nbsp; &nbsp; &nbsp; &nbsp;c = record1.getSchool().compareTo(record2.getSchool());&nbsp; &nbsp; return c;}