Question

How can I make this program sort strings that are in a text file and not have the user type them in? import java.util.*;
public class MergeDemo
{
public static void main(String args[])
{
Scanner input=new Scanner(System.in);
System.out.print("How many lines to be sorted:");
int size=input.nextInt();
String[] lines=new String[size];
lines[0]=input.nextLine();
System.out.println("please enter lines...");
for(int i=0;i {
lines[i]=input.nextLine();
}
System.out.println();
System.out.println("Lines Before Sorting:");
System.out.println(Arrays.toString(lines));
mergeSort(lines);
System.out.println();
System.out.println("Lines after Sorting:");
System.out.println(Arrays.toString(lines));
}

public static void mergeSort(String[] s)
{
if(s.length>1)
{
String[] left=Arrays.copyOfRange(s,0,s.length/2);
String[] right=Arrays.copyOfRange(s,s.length/2,s.length);
mergeSort(left);
mergeSort(right);
merge(s,left,right);
}
}
public static void merge(String[] result, String[] left, String[] right)
{
int i1 = 0;
int i2 = 0;
for (int i = 0; i < result.length; i++)
   {
   if (i2 >= right.length || (i1 < left.length &&left[i1].compareToIgnoreCase(right[i2])<0))
   {
result[i] = left[i1];
i1++;
}
   else
   {
result[i] = right[i2];
i2++;
}
}
}
}

Answer 1

import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;

public class MergeDemo {
   public static void main(String args[]) throws Exception {
       Scanner input = new Scanner(new File("lines.txt"));
       ArrayList<String> s = new ArrayList<String>();
       while (input.hasNextLine()) {
           s.add(input.nextLine());
       }
       String lines[] = (String[]) s.toArray();
       System.out.println();
       System.out.println("Lines Before Sorting:");
       System.out.println(Arrays.toString(lines));
       mergeSort(lines);
       System.out.println();
       System.out.println("Lines after Sorting:");
       System.out.println(Arrays.toString(lines));
   }

   public static void mergeSort(String[] s) {
       if (s.length > 1) {
           String[] left = Arrays.copyOfRange(s, 0, s.length / 2);
           String[] right = Arrays.copyOfRange(s, s.length / 2, s.length);
           mergeSort(left);
           mergeSort(right);
           merge(s, left, right);
       }
   }

   public static void merge(String[] result, String[] left, String[] right) {
       int i1 = 0;
       int i2 = 0;
       for (int i = 0; i < result.length; i++) {
           if (i2 >= right.length || (i1 < left.length && left[i1].compareToIgnoreCase(right[i2]) < 0)) {
               result[i] = left[i1];
               i1++;
           } else {
               result[i] = right[i2];
               i2++;
           }
       }
   }
}

//Instructions: write the lines into the linex.txt and put the file at same location where your java file is located

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