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I am having this issue getting the file input from one class and using it in another. So what happens is I have a file called readFile.java that reads in the line of a txt file. I have another file that I am using to evaluate a stack that I want to use the file input. So all in all, I am trying to find a way to replace my testInput string in my evalStack.java file with the file input from the readFile.java.

Here is the readFile.java:

import java.util.Scanner;

import java.io.*;

public class readFile {
    String fname;

    public readFile() {
        System.out.println("Constructor");
        getFileName();
        readFileContents();
    }

    public void readFileContents()
    {
        boolean looping;
        DataInputStream in;
        String line;
        int j, len;
        char ch;

        /* Read input from file and process. */
        try {
            in = new DataInputStream(new FileInputStream(fname));

            looping = true;
            while(looping) {
                /* Get a line of input from the file. */
                if (null == (line = in.readLine())) {
                    looping = false;
                    /* Close and free up system resource. */
                    in.close();
                }
                else {
                    System.out.println("line = "+line);
                    j = 0;
                    len = line.length();
                    for(j=0;j<len;j++){
                        System.out.println("line["+j+"] = "+line.charAt(j));
                    }
                }
            } /* End while. */

        } /* End try. */

        catch(IOException e) {
            System.out.println("Error " + e);
        } /* End catch. */
    }

    public void getFileName()
    {
        Scanner in = new Scanner(System.in);

        System.out.println("Enter file name please.");
        fname = in.nextLine();
        System.out.println("You entered "+fname);
    }
}

This is the evalStack.java:

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

public class evalStack {

    static String testInput = "(6+3) + (3-2)";
    //This is the line I want to replace with the input the readFile gives me.

    public static void main(String[] args){

        int maxLength = testInput.length();
        stackOb eval = new stackOb(maxLength);
        boolean test = false;

        //Evaluate and check parenthesis
        for(int i = 0; i < testInput.length(); i++)
        {
            char a = testInput.charAt(i);

            if(a=='(')
            {
                eval.push(a);
            }
            else if(a==')')
            {
                if(eval.empty() == false)
                {
                    eval.pop();
                }
                else
                {
                    test = true;
                    System.out.println("The equation is a not valid one.");
                    System.exit(0);
                }
            }
            else
            {
                continue;
            }
        }
        if(eval.empty() == true && test == false)
        {
            System.out.println("The equation is a valid one.");
        }
        else
        {
            System.out.println("The equation is a not valid one.");
        }
    }
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1 回答 1

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  1. 将该行添加import readFile;到 evalStack.java 的顶部
  2. 更改输入：static String testInput = new readFile().readFileContents();
  3. 更改返回类型：public String readFileContents()
  4. 替换j = 0;为return line;

这将使它评估第一行。

于 2013-10-07T03:17:20.310 回答