Question

此代码的目的是使用HashMaps和Streams计算按顺序出现的字母实例。

我遇到的问题是我的System.out.print（结果）正在打印[is = 3，imple = 2，it = 1]到控制台，但我的junit说“预期＆lt; [是= 3 imple = 2 it = 1]＆gt;但是＆lt; []＆gt;。

代码打印出[is = 3，imple = 2，it = 1]，但实际上并没有将其更新到内存中。关于我应该做什么的任何提示或建议？非常感谢你！

import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;

public class WordCount {

protected Map<String, Integer> counts;
static Scanner in= new Scanner(System.in);

public WordCount(){

    counts = new HashMap<String,Integer>();

}
public Map getCounts(){

    return counts;
}

public int parse(Scanner in, Pattern pattern){
        int counter=0;
        while   (in.hasNext())  {
        //  get the next    token
        String  token   =   in.next();
        //  match   the pattern within  the token
        Matcher matcher =   pattern.matcher(token);
        //  process each    match   found   in  token   (could  be  more    than    one)
        while   (matcher.find())    {
                        //  get the String  that    matched the pattern
            String  s   =   matcher.group().trim();
                        //  now do  something   with    s

            counter=counts.containsKey(s) ? counts.get(s):0;
            counts.put(s,counter+1);
            }

        }


        return counter;
}


public void report(PrintStream printstream){
    List<Map.Entry<String, Integer>> results = new ArrayList<Map.Entry<String, Integer>>();
    for(Map.Entry<String, Integer> entry: counts.entrySet()){
        results.add(entry);
        Collections.sort(results,Collections.reverseOrder(Map.Entry.comparingByValue()));
        results.toString();

    }



    System.out.println(results); // The main problem is this outputs [is=3, 
imple=2, it=1] but the junit doesn't pass.


}


}

//Test Cases 


import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.Scanner;
import java.util.regex.Pattern;

import junit.framework.TestCase;

public class TestWordCount extends TestCase {
public void test_WordCount_parse() {
    WordCount wc = new WordCount();
    Scanner in = new Scanner("this is a simple test, but it is not simple to pass");
    Pattern pattern = Pattern.compile("[i][a-z]+");
    wc.parse(in, pattern);

    assertEquals((Integer)3, wc.getCounts().get("is"));
    assertEquals((Integer)2, wc.getCounts().get("imple"));
    assertEquals((Integer)1, wc.getCounts().get("it"));

}

    public void test_WordCount_report() {
    WordCount wc = new WordCount();
    Scanner in = new Scanner("this is a simple test, but it is not simple to pass");
    Pattern pattern = Pattern.compile("[i][a-z]+");
    wc.parse(in, pattern);

    ByteArrayOutputStream output = new ByteArrayOutputStream();
    wc.report(new PrintStream(output));
    String out = output.toString();
    String ls = System.lineSeparator();

    assertEquals("is=3_imple=2_it=1_".replace("_", ls), out);
   }

Answer 1

`public void report(PrintStream printstream)`

在此方法中，您不会向printstream打印任何内容。尝试添加

printstream.print(results);

这种方法。

请注意，虽然System.out本身就是PrintStream，但它是绑定到控制台的不同流。

计算字母序列的实例

1 个答案: