題目：刷卡記錄：名字-金錢    讀取並找出刷卡次數最多，單筆消費最多

程式碼：

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map.Entry;


//刷卡記錄：名字-金錢    讀取並找出刷卡次數最多，單筆消費最多

public class IoTest {
    
	public static void main(String[] args) {
		
		FileReader fr =null;
		BufferedReader br= null;
		ArrayList<Node> al = new ArrayList<Node>();
		HashSet<String> set = new HashSet<String>();
		HashMap<String, Integer> map = new HashMap<String, Integer>();
       try {
		     fr = new FileReader("d://test.txt");
    	     br = new BufferedReader(fr);
    	     String n = "";
    	     //readLine 如果到流末尾則會返回null
    	     while ((n=br.readLine())!=null)
    	     {
    	    	 //封裝成類
    	    	 String node[] =n.split("-");
    	    	 Node node1 = new Node(node[0], Float.parseFloat(node[1]));
    	    	 set.add(node[0]);
    	    	 al.add(node1);
    	    	// System.out.println(node1.name);
    	     }
    	     
    	     //找出單筆最大花費的人
    	     String maxName = "";
    	     for (int i =1;i<al.size();i++)
    	     {
    	    	 Node node = al.get(i);
    	    	 
    	    	 if(node.cost>al.get(i-1).cost)
    	    	 {
    	    		 maxName = node.name;
    	    	 }
    	     }
    	     System.out.println("單筆花費最多的人是："+maxName);
    	     
    	  /* for(int i=0;i<al.size();i++)
    	   {
    		   System.out.println(al.get(i).name+"  "+al.get(i).cost);
    	   }*/
    	       
    	     
    	      //遍歷set得到各個人的刷卡次數，儲存到map中
    	      Iterator<String> iter = set.iterator();
    	       
    	      while (iter.hasNext()) {
    	        String name = (String) iter.next();
    	        
    	        int count =0;
    	        for(int i =0;i<al.size();i++)
    	        {   
    	    
    	        	if(al.get(i).name.equals(name))
    	        	{
    	        		count++;
    	        	}
    	        	
    	        }
    	        map.put(name, count);
    	        
                  
    	   }
    	    
    	    //遍歷map得到每個人的刷卡次數
    	    Iterator iter2 = map.keySet().iterator();
  	        while(iter2.hasNext())
  	        {
  	        	String name2 =(String) iter2.next();
  	        	int count = map.get(name2);
  	        	System.out.println(name2+"  次數： "+count);
  	        }
	} catch (Exception e) {
		// TODO: handle exception
		e.printStackTrace();
	}
       //關閉檔案
       finally{
    	   try {
		   br.close();
    	   fr.close();
		} catch (Exception e2) {
			// TODO: handle exception
			e2.printStackTrace();
		}
    	
       }
	}
 
}

//資訊記錄類
class Node{
	String name;
	float cost;
	public Node(String name ,float cost)
	{
		this.cost=cost;
		this.name= name;
	}
}