Question

我必须为实验室编写这个程序。我必须基本上说明一个hashmap是什么（键和值）以及声明，.add（）,. get（）的基本操作，以及如何从地图中获取键和值。然后，您将使用woodchucks.txt输入文件将其应用于频率直方图问题。我已经完成了这一切，但我仍然坚持如何编写打印直方图的方法。有人可以帮帮我吗？

import java.io.*;
import java.util.*;

public class Lab8
{
public static void main(String args[]) throws Exception
{
    BufferedReader infile = new BufferedReader(new FileReader(args[0]));
    HashMap<String,Integer> histogram = new HashMap<String,Integer>();
    String word;
    while ( (word = infile.ready()) != null )
    {
        if(histogram.get(word)==null)
            histogram.put(word,1);
        else
            histogram.put(word, histogram.get(word)+1);

    }   
             // YOUR CODE HERE

    infile.close();
    printHistogram( histogram );

} // END MAIN
// YOU FILL IN THIS METHOD
// READ PROBLEM SPECIFICATION TO SEE WHAT IS THE 80% vs 100% CREDIT SOLUTION

private static void printHistogram( HashMap<String,Integer> hm )
{

    // YOU CODE HERE
}
} // END LAB8 CLASS

我会像这样打印直方图吗？

for ( int i = 0; i < histogram.length; i++ )
         {
         output += "\n" + i + "\t" + histogram[ i ] + "\t";

         for ( int j = 1; j <= histogram[ i ]; j++ )

Answer 1

所以如果我要这样做，我会从创建两个类开始，一个可以保存单词和数字出现的类，例如我的HistogramItem

public class HistogramItem implements Comparable<HistogramItem> {
        @Override
        public String toString() {
            return "HistogramItem [word=" + word + ", occurence=" + occurence
                    + "]";
        }

        public int getOccurence() {
            return occurence;
        }

        public void updateOccurence() {
            this.occurence++;
        }

        public String getWord() {
            return word;
        }

        public HistogramItem(String word) {
            super();
            this.word = word;
        }

        private final String word;
        private int occurence = 0;

        @Override
        public int compareTo(HistogramItem o) {

            if (occurence == o.occurence) {
                return word.compareTo(o.word);
            }
            return o.occurence-occurence;
        }

    }

和另一个将是我的实际直方图

public class Histogram {
        private Map<String, HistogramItem> map = new HashMap<>();
        private List<HistogramItem> list = new ArrayList<>();

        public void addWord(String word) {
            HistogramItem item = map.get(word);
            if (item == null) {
                item = new HistogramItem(word);
                map.put(word, item);
                list.add(item);
            }
            item.updateOccurence();
        }

        public List<HistogramItem> getList() {
            Collections.sort(list);
            return list;
        }

    }

我正在使用两个集合hashmap，因为搜索条目比列表中的要快得多，但是列表更容易排序，列表可以在请求时创建和排序

这如何适合您原来的运动？简单

public static void main(String args[]) throws Exception
{
    BufferedReader infile = new BufferedReader(new FileReader(args[0]));
    Histogram histogram = new Histogram();
    String word;
    while ( (word = infile.ready()) != null )
    {
       histogram.addWord(w);

    }   
             // YOUR CODE HERE

    infile.close();

//   Below line prints histogram, can be placed in printHistogram method
for (HistogramItem item : histogram.getList()) {
            System.out.println(item.toString());
        }

} // END MAIN

Answer 2

我明白了，这就是答案......

import java.io.*;
import java.util.*;

public class Lab8
{
public static void main(String args[]) throws Exception
{
    BufferedReader infile = new BufferedReader(new FileReader(args[0]));
    HashMap<String,Integer> histogram = new HashMap<String,Integer>();
    String word;
    while ((infile.ready()))
    {
        word = infile.readLine();
        if(histogram.get(word)== null) //if the word your currently on is not duplicated
        {
            histogram.put(word,1);
        }
        else
        {
            histogram.put(word, histogram.get(word)+1);
        }
    }   
             // YOUR CODE HERE

    infile.close();
    printHistogram( histogram );

} // END MAIN
// YOU FILL IN THIS METHOD
// READ PROBLEM SPECIFICATION TO SEE WHAT IS THE 80% vs 100% CREDIT SOLUTION

private static void printHistogram( HashMap<String,Integer> hm )
{
    List <String> keys = new ArrayList<String> (hm.keySet());   
    Collections.sort(keys);
    for (String key: keys) 
    {
        System.out.println(key + "\t"  + hm.get(key));

    }
} 
}// END LAB8 CLASS

如何编写打印直方图的方法？

2 个答案: