Question

我需要一个查找特定文件的方法的帮助，然后从该文件中打印出一行文本。如果在控制台中键入的字符串与该行文本中的字符串匹配，则会打印文本行。例如，如果我打电话给java Find ring report.txt address.txt Homework.java，它应该打印如下：

report.txt: has broken up an internationa ring of DVD bootleggers that

address.txt: Kris Kringle, North Pole

address.txt: Homer Simpson, Springfield

Homework.java: String file name;

指定的单词始终是第一个命令行参数。

这是我到目前为止所做的：

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;


/**
 * Code for E11.8. Searches all files specified on the command line and prints out all lines     
  containing a specified word.
 * @Michael Goedken
 */
public class Find
{
   /**
      Searches file for a word, prints out all lines containing that word.
      @param wordToFind the word to find
      @param filename the filename for the file to search
   */
   public static void findAndPrint(String wordToFind, String filename)
   {
   String input = args[0];
   for (int i = 1; i < args.length; i++)
   {
       System.out.println(" File  " + args[i]);
        File one = new File(args[i]);
        Scanner in = new Scanner(one);

        while (in.hasNext())
       {
           String line = in.nextLine();
            if (line.contains(input))
            {
               System.out.println(line);
            }
       }
   }


}

   /**
      First argument of the main method should be the word to be searched
      For other arguments of the main method, store the file names to be examined
   */
public static void main(String[] args)
{
   // call findAndPrint for each text file



   }
 }

Answer 1

您正在尝试访问不在函数args[]范围内的数组findAndPrint()。您需要将args[0]作为参数传递给main方法中的函数调用语句：

public static void main(String[] args){
    findAndPrint(args[0], args[1]); //for report.txt
    findAndPrint(args[0], args[2]); //for address.txt
}

args是主要方法的参数。它是一个String数组，用于存储各个命令行输入。在您的情况下，数组args[]的内容为= {"ring", "reports.txt", "address.txt", "Homework.java"}。

您现在可以通过以下方式修改findAndPrint()功能：

static void findAndPrint(String wordToFind, String filename){
    Scanner fscan = new Scanner(new File(filename));
    String str = "";
    while((str = fscan.nextLine()) != null){
        if(str.contains(wordToFind))
            System.out.println(str);
    }
}

Answer 2

我添加了主要论点。我没有运行代码，所以你可以调试和测试。

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;


/**
 * Code for E11.8. Searches all files specified on the command line and prints out all lines containing a specified word.
 * @Michael Goedken
 */
public class Find {
  /** Searches file for a word, prints out all lines containing that word.
  @param wordToFind the word to find
  @param filename the filename for the file to search
  */
  public static void findAndPrint(String wordToFind, String filename) {
   System.out.println(" File  " + filename);
   File one = new File(filename);
   Scanner in;
   try {
       in = new Scanner(one);
       while (in.hasNext()) {
           String line = in.nextLine();
           if (line.contains(wordToFind)) {
               System.out.println(line);
           }
       }
   } catch (FileNotFoundException e) {
        e.printStackTrace();
   }
}




public static void main(String[] args) {
    int length = args.length;
    if (length > 0 ) {
        String wordToFind = args[0];
        // now gather file names, bypassing first string
        for (int ii = 1; ii < length; ii++) {
            findAndPrint(wordToFind, args[ii]);         
        }
    }
}

}

Answer 3

这似乎是一种解决方案！

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Scanner;


/**
 * Code for E11.8. Searches all files specified on the command line and prints     out all lines     
   containing a specified word.
 * @Michael Goedken
 */
public class Find
{
   /**
   Searches file for a word, prints out all lines containing that word.
  @param wordToFind the word to find
  @param filename the filename for the file to search
   */
   public static void findAndPrint(String wordToFind, String filename) throws FileNotFoundException
{
   Scanner in = new Scanner(new FileReader(filename));

   String input = wordToFind;
   while (in.hasNext()) 
   {
      String line = in.nextLine();
      if (line.contains(input)) 
      {
           System.out.println(line);
      }
   }
 }

/**
  First argument of the main method should be the word to be searched
  For other arguments of the main method, store the file names to be examined
*/
   public static void main(String[] args) throws FileNotFoundException
{
  // call findAndPrint for each text file

   findAndPrint("tt", "/Users/MichaelGoedken/Desktop/mary.txt");

   findAndPrint("0", "/Users/MichaelGoedken/Desktop/transactions.txt");

  }
}

Answer 4

好的，我想我现在就得到了你的问题。

您可以从主要方式调用您的方法：

public static void main(String[] args) {
//may need to throw file not found exception here
        findAndPrint();
    }

然后你需要从方法中删除参数：

public static void findAndPrint() throws FileNotFoundException {
        Scanner in = new Scanner(new FileReader("C:\\yourfilepath\\actualfile.txt"));
        //you can get user input etc here if necessary
        String input = "pass";
        while (in.hasNext()) {
            String line = in.nextLine();
            if (line.contains(input)) {
                System.out.println(line);
            }
        }
    }

查找和搜索文件JAVA的方法

4 个答案: