定义一个Rectangle类，该类提供getLength和getWidth方法。

import java.util.Comparator;

/**
* 定义一个Rectangle类，该类提供getLength和getWidth方法。利用图1-18中的findMax例程编写
* 一种main方法，该方法创建一个Rectangle数组并首先找出依面积最大的Rectangle对象，然后
* 找出依周长最大的Rectangle对象。
* @author wulei
*/
public class RectangleTest {
/**
* 构造一个矩形
*/
private int width,height;
private String name;

public RectangleTest(int width, int height){
this.width = width;
this.height = height;
}

public int getLength(){
return (width+height)<<2;
}

public int getArea(){
return width*height;
}

public String getName(){
return "("+width+","+height+")";
}

public static <T> T findMax(T[] arr,Comparator<? super T> cmp){
if(null == arr || cmp == null){
return null;
}
int index = 0;
for (int i = 1; i < arr.length; i++) {
if(cmp.compare(arr[i], arr[index]) > 0){
index = i;
}
}
return arr[index];
}

/**
* 长度比较器
*/
public static class LengthCompare implements Comparator<RectangleTest>{

@Override
public int compare(RectangleTest o1, RectangleTest o2) {
if(o1.getLength() > o2.getLength()){return 1;}
else if (o1.getLength() == o2.getLength()) {
return 0;
}else{
return -1;
}
}

}

/**
* 面积比较器
*/
public static class AreaCompare implements Comparator<RectangleTest>{

@Override
public int compare(RectangleTest o1, RectangleTest o2) {
if(o1.getArea() > o2.getArea()) {return 1;}
else if (o1.getArea() == o2.getArea()) {
return 0;
}
else {
return -1;
}
}

}

public static void main(String[] args) {
RectangleTest[] arr = new RectangleTest[]
{new RectangleTest(5, 5),new RectangleTest(6,4),new RectangleTest(3, 8)};
System.out.println(findMax(arr, new LengthCompare()).getName());
System.out.println(findMax(arr, new AreaCompare()).getName());
}

}