Java -- ArrayList排序

package team.bean;

import java.io.IOException;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class CollectionsTest {

public static void main(String[] args) throws IOException {

List<Number> dataSet = new ArrayList<Number>();
dataSet.add(1);
dataSet.add(9.6);
dataSet.add(9.97F);
dataSet.add(9.99F);
dataSet.add(9.98F);
dataSet.add(-2);
dataSet.add((short)8);
dataSet.add(new BigDecimal(7.8));
dataSet.add(new BigDecimal(7.9));
System.out.println(Collections.max(dataSet,new Com()));
Collections.sort(dataSet,new Com());
System.out.println();
//System.out.println(dataSet.get(0).toString());
}
}

class Com implements Comparator<Number>{

@Override
public int compare(Number o1, Number o2) {
Double num = (Double.parseDouble(o1.toString())-Double.parseDouble(o2.toString()));
if(num>0)
return 1;
else if(num<0)
return -1;
else return 0;
}

}