原创 策略设计模式实例（欢迎指正交流）
在网页http://topic.csdn.net/u/20090916/00/8204215a-73c8-4939-9ccf-258ded13e33f.html上看到一道面试题，如下：
利用Java中的接口来实现设计模式中的策略模式，需要编写程序如下：
public interface Relation{
boolean Releation(int a,int b); }
利用上述接口，编写一个函数
IntGetMaxChainLen(int[] intArray,Relation relation);
intArray为一个整形数组，该数组中，假如相令俩整数a,b。使得Relation(a,b)为true,则认为a,b形成一段链；计算该数组中（根据Relation关系）最长的链的长度；
假如没有这样的链返回为0；
要求：根据上述条件，代码中要实现GetMaxChainLen函数，还要给出一中Releation的实现。给出完整可运行的测试代码。
自己动手编写的程序如下：
package stratagy.chainLength;
public interface Relation {
public boolean relation(int a,int b);
}
package stratagy.chainLength;
public class RelationEqual implements Relation {
public boolean relation(int a, int b) {
// TODO Auto-generated method stub
return (a==b);
}
}
package stratagy.chainLength;
public class RelationGreater implements Relation {
public boolean relation(int a, int b) {
// TODO Auto-generated method stub
return a>b;
}
}
package stratagy.chainLength;
public class RelationLess implements Relation {
public boolean relation(int a, int b) {
// TODO Auto-generated method stub
return (a<b);
}
}
package stratagy.chainLength;
public class Chain {
private Relation relation;
private int[]chain ;
public void setRelation(Relation relation) {
this.relation = relation;
}
public Chain(Relation relation, int[] chain) {
super();
this.relation = relation;
this.chain = chain;
}
int getMaxChainLen(int[] chain,Relation relation){
int maxLength = 0;
int a;
int b;
for(int i = 0;i < chain.length - 1;i++){
a = chain[i];
b = chain[i + 1];
if(relation.relation(a, b)){
maxLength++;
}
}
return maxLength;
}
}
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Relation relation = new RelationGreater();
int [] intArray = {2,5,-4,8,8,90,-12,0,0,0,-4,5,67,23,21};
Chain chain = new Chain(relation,intArray);
System.out.println(chain.getMaxChainLen(intArray, relation));
relation = new RelationEqual();
chain.setRelation(relation);
System.out.println(chain.getMaxChainLen(intArray, relation));
relation = new RelationLess();
System.out.println(chain.getMaxChainLen(intArray, relation));
}
}
输出结果如下：
5
3
6
