从文本文件中读取整数并将其放入已排序的数组中

Question

I've been scratching my head on this all day trying to figure out how to do this. I have tried multiple different ways, but I feel I've been going about this all wrong. My assignment is to read 50 integers from a .txt file and put the contents into a sorted array, then list the highest/lowest/average number, but I can hardly get past step one.

These are the 50 numbers in the text file

64 61 169 113 81 61 206 176 39 100 22 200 128 152 59 165 67 116 165 72 26 149 58 204 188 69 203 94 96 134 83 122 192 85 62 159 35 162 95 92 126 66 66 203 187 18 132 182 181 175

In this file I've managed to get the "proj8" file to at least print.

import java.util.Scanner;
import java.io.IOException;
import java.util.ArrayList;
import java.util.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.List;
import java.io.*;

public class ect7{

  public static void main(String[] args) throws IOException {

    BufferedReader br = new BufferedReader(new FileReader("proj8.txt"));

    String line = br.readLine();

    while ((line = br.readLine()) != null) {
      System.out.println(line);
    }
    br.close();
  } 
}

In this file I've managed to get the "proj8" file to print and somewhat order them, but insanely so.

import java.util.Scanner;
import java.io.IOException;
import java.util.ArrayList;
import java.util.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.List;
import java.io.*;

public class ect73{

public static void main(String[] args) throws IOException {

  //int [] myArr = new int[50];  
  //FileReader fr = new FileReader("proj8.txt");    
  BufferedReader br = new BufferedReader(new FileReader("proj8.txt"));
  List<String> lines = new ArrayList<String>();
  String line = null;

  //String line = br.readLine();

   while ((line = br.readLine()) != null) {
     lines.add(line);
     Collections.sort(lines);
     //System.out.println(line);
     System.out.println(lines);
   }   
   br.close();
   //return lines.toArray(new String[lines.size()]);
  }
}

I know I'm doing this all wrong but I have no idea how to do this right. I need to be able to input the .txt file into a sorted array in integer and then list the highest/lowest/average number. Any help is good help, but the more simple the code the better.

Answer 1

you are trying to sort lines of the file which contains several numbers separated by space. you have to split each line into numbers and for each number you have to parse it as an Integer and store those in the ArrayList . finally you can sort the ArrayList .

    BufferedReader br = new BufferedReader(new FileReader("proj8.txt"));
    List<Integer> numbers = new ArrayList<Integer>();
    String line = null;

     //String line = br.readLine();

     while ((line = br.readLine()) != null) {
         String []strNumbers = line.split(" ");
         for(String strNumber : strNumbers){
             numbers.add(Integer.parseInt(strNumber));
         }

         //System.out.println(line);            
     }   
     br.close();

     Collections.sort(numbers);
     System.out.println(numbers);

Answer 2

You're on the right track but looking at your file it looks like it contains more than one number per line so you need to handle this. You also need to convert them to numbers or they will be sorted as strings (meaning that "10" comes before "2").

I'm not going to give you the whole answer but here are a few methods/classes you can use to solve this:

• java.util.Scanner
• String.split(String regex)
• Integer.parseInt(String s)
• Arrays.sort(int[] array)

You won't have to use all of these, but they should be able to help you find a solution.

Answer 3

You dont have to go with complex methods all you have to do is to open the file create a scanner object. 1 for loop to construct the array from the text file 1 for loop to find the lowest/highest value and the sum of all values. then you compute the average and you output all results.

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

public class textToArray {

        public static void main(String[] args) throws FileNotFoundException{
        //Open the file 
        File f = new File("C:\\Users\\YOUR COMPUTER\\Desktop\\java.txt");//when the file directory contain \ you need to use escape ex "c:\\user\\desktop"
        //Create a new scanner to read the file
        Scanner s = new Scanner(f);
        //Declare an array with length of 100
        int[] array = new int[100];
        int i = 0, min, max, sum = 0;
        //Loop through the file if there is a next int to process it will continue

        for(i = 0; s.hasNextInt(); i++){
            //We store every int we read in the array
            array[i] = s.nextInt();                             
        }

        //Close the scanner object
        s.close();
        //As the for loop will stop when there is no new int to read so the i++ will stop at the number of int in the file
        //We use this number to calculate the average
        int nbInArray = i;
        //initialize min and max to the first array value which is for now empty
        min = max = array[0];
        for(int j = 0; j<nbInArray ; j++){
            //Now we test if the new value if bigger than the initial value (0 or empty) the new value will become the max
            if (array[j]>max){
                max = array[j];
                }
            //Otherwise if the the value is smaller than the initial value the new value will become the minimum
            //And so on every time we test if we have a smaller value the new one will become the min
            if (array[j]<min){
                min = array[j];
                }
            //The sum was initialised to 0 so we add every new int to it
            sum = sum + array[j];
        }


        //We compute the avg , i declared it double in case we have decimal results
        double avg = sum / nbInArray;
        //finally we print out the min, max and the average
        System.out.println("The minimum is: "+min);
        System.out.println("The maximum is: "+max);
        System.out.println("The averange is: "+avg);

}
}