Question

public class Main {


public static void main(String[] args)
{
int ch = 0;
do
{

Scanner in = new Scanner(System.in);

String s;
System.out.println("Enter the part number");
s=in.nextLine();

try{

  BufferedReader br = new BufferedReader(new FileReader("C:\\Users\\Ankit\\Documents\\NetBeansProjects\\tcs_1\\number.txt"));
  BufferedReader Br = new BufferedReader(new FileReader("C:\\Users\\Ankit\\Documents\\NetBeansProjects\\tcs_1\\number1.txt"));

  String strLine;
  int flag=0;
  while ((strLine = br.readLine()) != null)
  {
        if(strLine.equals(s))
        {
            flag=1;
            System.out.println ("Part Number exists in 1");
            break;
        }
        else
        {
            flag=0;
            System.out.println ("Part Number doesnot exist in 1");
            break;
        }


    }

    if(flag==0)
    {

        while ((strLine = Br.readLine()) != null)
        {
            if(strLine.equals(s))
            {
                System.out.println ("Part Number exists in 2");
                break;
            }
     else
            {
                System.out.println("File does not exist in 2");
                break;
     }

        }
    }
        System.out.println ("Do you want to continue-Press1 for yes and 2 for no");

        ch= in.nextInt();
        br.close();
        Br.close();

}
catch (Exception e)
{
    System.err.println("Error: " + e.getMessage());
  }
}
while(ch==1);
  }
}

这是我用2个差异文本文件搜索给定字符串的用户的程序。它的工作正常，但只搜索第一行。例如：如果文件有 1000 1001 1002 它只会搜索1000.如何进入下一行并继续使用.equals()方法？

Answer 1

你应该使用Scanner not BufferedReader，因为它是一个更新的类我觉得这项工作做得更好。特别是因为你有已经在代码中的其他位置使用了Scanner，从而导入了它。下面是一个扫描仪，它将读取文件中的所有行是下一个要读的。

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

public class JavaApplication32 
{
    public static void main(String[] args) 
    {
        Scanner keyboard = new Scanner(System.in);
        Scanner scanner1 = null;
        Scanner scanner2 = null;
        String partCheck;
        String repeatLoop;
        boolean isInOne;
        boolean isInTwo;

        File file1 = new File("data1.txt");
        File file2 = new File("data2.txt");

        try
        {
            scanner1 = new Scanner(file1);
            scanner2 = new Scanner(file2);
        }
        catch(FileNotFoundException e)
        {
            e.printStackTrace();
        }
            do
            {
                isInOne = false;
                isInTwo = false;
                System.out.println("Enter the part number");
                partCheck = keyboard.nextLine();
                while (scanner1.hasNextLine() && !isInOne)
                {
                    String line = scanner1.nextLine();
                    if(line.equals(partCheck))
                    {
                        System.out.println("Part Number exists in 1");
                        isInOne = true;
                    }
                }
                if(!isInOne)
                {
                    System.out.println("Part Number does not exist in 1");
                }
                while(scanner2.hasNextLine() && !isInOne && !isInTwo)
                {
                    String line = scanner2.nextLine();
                    if(line.equals(partCheck))
                    {
                        System.out.println("Part Number exists in 2");
                        isInTwo = true;
                    }
                }
                if(!isInTwo)
                {
                    System.out.println("Part Number does not exist in 2");
                }
                System.out.println("Do you want to continue? (Y/N)");
                repeatLoop = keyboard.nextLine();
            } while(repeatLoop.equalsIgnoreCase("y"));
        scanner1.close();
        scanner2.close();
    }
}

示例文本文件data1.txt：

Test1
Test2
Test3
Test4

示例测试文件data2.txt

Check1
Check2
Check3
Check4

使用这些数据文件运行代码时的stdout示例：

run:
Enter the part number
Test1
Part Number exists in 1
Part Number does not exist in 2
Do you want to continue? (Y/N)
y
Enter the part number
Check1
Part Number does not exist in 1
Part Number exists in 2
Do you want to continue? (Y/N)
n
BUILD SUCCESSFUL (total time: 19 seconds)

您也不应该将所有读入的信息都放在循环中。通过把它放在最顶层你有效地继续创建一组新的 BufferedReaders并将它们命名为相同的东西并告诉它们同样的事情，然后告诉他们在第一次打击后打破。如果你确实摆脱了自那以后你会遇到更多问题的突破所有这些其他的东西都在它不应该的循环中。

Answer 2

因为你已经使用过

 break;

在while循环中，它将在检查第一行后退出循环。尝试删除休息;如果你想阅读所有的行。

从文件中读取字符串数据

2 个答案: