Android

如果你要查找默认排序，则应使用Comparable而不是Comparator。

看到这里，这可能会有帮助- 类何时应该是Comparable和/或

Comparator

尝试这个

import java.util.ArrayList;import java.util.Collections;import java.util.List;public class TestSort {    public static void main(String args[]){        ToSort toSort1 = new ToSort(new Float(3), "3");        ToSort toSort2 = new ToSort(new Float(6), "6");        ToSort toSort3 = new ToSort(new Float(9), "9");        ToSort toSort4 = new ToSort(new Float(1), "1");        ToSort toSort5 = new ToSort(new Float(5), "5");        ToSort toSort6 = new ToSort(new Float(0), "0");        ToSort toSort7 = new ToSort(new Float(3), "3");        ToSort toSort8 = new ToSort(new Float(-3), "-3");        List<ToSort> sortList = new ArrayList<ToSort>();        sortList.add(toSort1);        sortList.add(toSort2);        sortList.add(toSort3);        sortList.add(toSort4);        sortList.add(toSort5);        sortList.add(toSort6);        sortList.add(toSort7);        sortList.add(toSort8);        Collections.sort(sortList);        for(ToSort toSort : sortList){ System.out.println(toSort.toString());        }    }}public class ToSort implements Comparable<ToSort> {    private Float val;    private String id;    public ToSort(Float val, String id){        this.val = val;        this.id = id;    }    @Override    public int compareTo(ToSort f) {        if (val.floatValue() > f.val.floatValue()) { return 1;        }        else if (val.floatValue() <  f.val.floatValue()) { return -1;        }        else { return 0;        }    }    @Override    public String toString(){        return this.id;    }}