Java ArrayList Sort

    Collections.sort(hits_list, new Comparator<ScoreDoc>(){  
                    @Override
                    public int compare(ScoreDoc arg0, ScoreDoc arg1) {
                        if( arg0.score < arg1.score ) return 1;
                        return 0;
                    }
                } 
            );

 

重写一个比较对象便可。