170、从类似如下的文本文件中读取出所有的姓名,并打印出重复的姓名和重复的次数,并按重复次数排序:
1,张三,28 2,李四,35 3,张三,28 4,王五,35 5,张三,28 6,李四,35 7,赵六,28 8,田七,35
程序代码如下(答题要博得用人单位的喜欢,包名用该公司,面试前就提前查好该公司的网址,如果查不到,现场问也是可以的。还要加上实现思路的注释): package com.huawei.interview; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.Comparator; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.TreeSet; public class GetNameTest {
/** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub //InputStream ips = GetNameTest.class.getResourceAsStream("/com/huawei/interview/info.txt"); //用上一行注释的代码和下一行的代码都可以,因为info.txt与GetNameTest类在同一包下面,所以,可以用下面的相对路径形式 Map results = new HashMap(); InputStream ips = GetNameTest.class.getResourceAsStream("info.txt"); BufferedReader in = new BufferedReader(new InputStreamReader(ips)); String line = null; try { while((line=in.readLine())!=null) { dealLine(line,results); } sortResults(results); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } static class User { public String name; public Integer value; public User(String name,Integer value) { this.name = name; this.value = value; }
@Override public boolean equals(Object obj) { // TODO Auto-generated method stub //下面的代码没有执行,说明往treeset中增加数据时,不会使用到equals方法。 boolean result = super.equals(obj); System.out.println(result); return result; } } private static void sortResults(Map results) { // TODO Auto-generated method stub TreeSet sortedResults = new TreeSet( new Comparator(){ public int compare(Object o1, Object o2) { // TODO Auto-generated method stub User user1 = (User)o1; User user2 = (User)o2; /*如果compareTo返回结果0,则认为两个对象相等,新的对象不会增加到集合中去 * 所以,不能直接用下面的代码,否则,那些个数相同的其他姓名就打印不出来。 * */ //return user1.value-user2.value; //return user1.value<user2.value?-1:user1.value==user2.value?0:1; if(user1.value<user2.value) { return -1; }else if(user1.value>user2.value) { return 1; }else { return user1.name.compareTo(user2.name); } } } ); Iterator iterator = results.keySet().iterator(); while(iterator.hasNext()) { String name = (String)iterator.next(); Integer value = (Integer)results.get(name); if(value > 1) { sortedResults.add(new User(name,value)); } } printResults(sortedResults); } private static void printResults(TreeSet sortedResults) { Iterator iterator = sortedResults.iterator(); while(iterator.hasNext()) { User user = (User)iterator.next(); System.out.println(user.name + ":" + user.value); } } public static void dealLine(String line,Map map) { if(!"".equals(line.trim())) { String [] results = line.split(","); if(results.length == 3) { String name = results[1]; Integer value = (Integer)map.get(name); if(value == null) value = 0; map.put(name,value + 1); } } } }
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