java 计算字符串在文件中出现的次数
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Count the amount of times a string appears in a file
提问by Zomby
I'm trying to figure out how I would read a file, and then count the amount of times a certain string appears.
我试图弄清楚我将如何读取文件，然后计算某个字符串出现的次数。
This is what my file looks like, it's a .txt:
这是我的文件的样子，它是一个 .txt：
Test
Test
Test
Test
I want the method to then return how many times it is in the file. Any idea's on how I could go about doing this? I mainly need help with the first part. So if I was searching for the string "Test" I would want it to return 4.
我希望该方法返回它在文件中的次数。关于我如何去做这件事的任何想法？我主要需要第一部分的帮助。因此，如果我正在搜索字符串“Test”，我希望它返回 4。
Thanks in advanced! Hope I gave enough info!
先谢谢了！希望我提供了足够的信息！
采纳答案by GETah
Here you are:
这个给你：
public int countStringInFile(String stringToLookFor, String fileName){
int count = 0;
try{
FileInputStream fstream = new FileInputStream(fileName);
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
while ((strLine = br.readLine()) != null) {
int startIndex = strLine.indexOf(stringToLookFor);
while (startIndex != -1) {
count++;
startIndex = base.indexOf(stringToLookFor,
startIndex +stringToLookFor.length());
}
}
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
return count;
}
Usage: int count = countStringInFile("SomeWordToLookFor", "FileName");
用法： int count = countStringInFile("SomeWordToLookFor", "FileName");
回答by Austin
Add this method to your class, pass your FileInputStream to it, and it should return the number of words in a file. Keep in mind, this is case sensitive.
将此方法添加到您的类中，将您的 FileInputStream 传递给它，它应该返回文件中的单词数。请记住，这是区分大小写的。
public int countWord(String word, FileInputStream fis) {
BufferedReader in = new BufferedReader(new InputStreamReader(fis));
String readLine = "";
int count = 0;
while((readLine = in.readLine()) != null) {
String words = readLine.split(" ");
for(String s : words) {
if(s.equals(word)) count++;
}
return count;
}
Just wrote that now, and it's untested, so let me know if it works. Also, make sure that you understand what I did if this is a homework question.
现在才写出来，它未经测试，所以让我知道它是否有效。另外，如果这是一个家庭作业问题，请确保您理解我所做的。
回答by John D
If you have got to the point of reading in each file into a string I would suggest looking at the String method split.
如果您已经到了将每个文件读入字符串的程度，我建议您查看 String 方法 split。
Give it the string code 'Test' and it will return an array of type string - count the number of elements per line. Sum them up to get your total occurrence.
给它字符串代码“Test”，它将返回一个字符串类型的数组 - 计算每行的元素数。总结它们以获得您的总出现次数。
import java.io.*;
public class StringCount {
public static void main(String args[]) throws Exception{
String testString = "Test";
String filePath = "Test.txt";
String strLine;
int numRead=0;
try {
FileInputStream fstream = new FileInputStream(filePath);
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
while ((strLine = br.readLine()) != null) {
strLine = strLine + " ";
String [] strArry = strLine.split(testString);
if (strArry.length > 1) {
numRead = numRead + strArry.length - 1;
}
else {
if (strLine == testString) {
numRead++;
}
}
}
in.close();
System.out.println(testString + " was found " + numRead + " times.");
}catch (Exception e){
}
}
}
回答by ΦXoc? ? Пepeúpa ツ
I would do this:
我会这样做：
- open and read the file line by line,
- check how oft a line contains the given word...
- increase a global counter for that..
- 逐行打开并读取文件，
- 检查一行包含给定单词的频率...
- 为此增加一个全局计数器..
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new FileReader("Test.txt"));
Scanner sc = new Scanner(System.in);
System.out.print("Enter the subtring to look for: ");
String word = sc.next();
String line = in.readLine();
int count = 0;
do {
count += (line.length() - line.replace(word, "").length()) / word.length();
line = in.readLine();
} while (line != null);
System.out.print("There are " + count + " occurrences of " + word + " in ");
}
