使用Java中的可比较按两个字段升序和降序对对象列表进行排序

Question

I already found some result about sorting list of object using multiple fields, but i didn't understand how can i sort a list by two fields ascending order and descending order using comparable Here is my code, i want to sort the list by descending order (datejournal) then by ascending order for codejournal

public class journal implements Comparable<journal>{
    private String codeJournal;
    private String dateLivraison;
    private int qteJournal;

    public String getCodeJournal() {
        return codeJournal;
    }
    public void setCodeJournal(String codeJournal) {
        this.codeJournal = codeJournal;
    }
    public String getDateLivraison() {
        return dateLivraison;
    }
    public void setDateLivraison(String dateLivraison) {
        this.dateLivraison = dateLivraison;
    }
    public int getQteJournal() {
        return qteJournal;
    }
    public void setQteJournal(int qteJournal) {
        this.qteJournal = qteJournal;
    }
    @Override
    public String toString() {
        return "journal [codeJournal=" + codeJournal + ", dateLivraison=" + dateLivraison + ", qteJournal=" + qteJournal
                + "]";
    }
    @Override
    public int compareTo(journal arg0) {
        if(this.dateLivraison.equals(arg0.getDateLivraison())){
            return -this.dateLivraison.compareTo(arg0.getDateLivraison());
        }
    }
}

Answer 1

You can compare first DateJournal(in descending order) and after that CodeJournal(in ascending order) as given below:

@Override
public int compare(final journal j1, final journal j2) {
    int res;
    res = j2.getDateLivraison().compareTo(j1.getDateLivraison());
    if (res == 0)
        res = j1.getCodeJournal().compareTo(j2.getCodeJournal());
    return res;
}