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POHow to implement Insertion Sort?
 

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  1. POHow to implement Insertion Sort?
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    <p>Ok, my goal is to be able to sort a text file of single entry per line. Im stuck to the point where i have to create the Insertion class. How do i pass the single link list (my own implementation, not Java's) and what else do i need to pass as a parameter? Here's my code so far. P.S The reason im using my own implementation of the linked list is because i want to know how the thing works and how the various actions done using a linked list work.</p> <p>Any help would be greatly appreciated.</p> <p>The Main:</p> <pre><code> import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.DataInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileWriter; import java.io.IOException; import java.io.InputStreamReader; import java.util.Scanner; public class Sort { public static void main(String[] args) throws Exception { Scanner kb = new Scanner (System.in) ; File outputFile ; EntriesList list = new EntriesList () ; String line ; String entry ; String command ; String textContent ; // Create the new text file. If exists, it will continue to the next commands do { outputFile = new File("Entries.txt") ; if(!outputFile.exists()) { outputFile.createNewFile (); System.out.println("The file was created as Entries.txt"); System.out.println(""); } }while (!outputFile.exists()) ; // Define which file to stream in from FileInputStream fileIn = new FileInputStream("Entries.txt") ; DataInputStream input = new DataInputStream (fileIn) ; BufferedReader br = new BufferedReader (new InputStreamReader (input)) ; try { // Read each line of the file while ((line = br.readLine()) != null) { entry = line; list.insert(entry) ; } input.close() ; }catch (Exception e){ System.err.println("Error. Could not read the file") ; } //Welcome message + entry counter System.out.println("Welcome. \nYou about to sort " + list.count("Entries.txt") + " entries. \nPlease use the following commands [Add -add new entry, View -view entries before sorting, -i -Insertion Sort, -s -Selection Sort, -m -Merge Sort, Exit]: " ); System. out.println ("") ; command = kb.next() ; // User Input do { if (command.equalsIgnoreCase("Add")) { System.out.println("Enter String value:") ; entry = kb.next() ; textContent = entry ; System.out.println("Entry added successfully") ; try { //the "true" argument sets the FileWriter to append mode so that is does not overwrite the first time BufferedWriter out = new BufferedWriter(new FileWriter("Entries.txt", true)); out.write(textContent) ; out.newLine() ; out.close() ; }catch(IOException e) { System.out.println("Could not write to file") ; System.exit(0) ; } System.out.println ("Enter command:") ; command = kb.next() ; list.insert(entry) ; } else if (command.equalsIgnoreCase("View")) { if (!list.isEmpty()) { list.printList(); System.out.println ("Enter command:") ; command = kb.next() ; } else { System.out.println("File is empty. Please enter records first."); System.out.println ("Enter ADD command:") ; command = kb.next(); } } else if (command.equalsIgnoreCase("Exit")) { System.exit(0) ; } else { System.out.println("Unknown command. Please use ADD, VIEW or EXIT") ; command = kb.next() ; } }while (!command.equalsIgnoreCase("Exit")) ; } } </code></pre> <p>The List implementation:</p> <pre><code> import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; public class EntriesList { private Entries head; private int listCount ; //LinkList constructor public EntriesList() { head = new Entries (null) ; listCount = 0 ; } //Returns true if list is empty public boolean isEmpty() { return head == null; } //Inserts a new Entry at the end of the list public void insert(String entryIn) { Entries temp = new Entries (entryIn) ; Entries current = head ; // Go to the end of the list while (current.getNext() != null) { current = current.getNext() ; } // Last Entries's next reference is set to the noew node current.setNext(temp) ; listCount++ ; } //Return the size of the list public int size() { return listCount ; } //Prints list data public void printList() { Entries currentEntry = head; while(currentEntry != null) { currentEntry.printLink(); currentEntry = currentEntry.nextEntry; } System.out.println(""); } // Count the lines in the text file public int count(String filename) throws IOException { InputStream is = new BufferedInputStream(new FileInputStream(filename)); try { byte[] c = new byte[1024] ; int count = 0 ; int readChars = 0 ; while ((readChars = is.read(c)) != -1) { for (int i = 0 ; i &lt; readChars ; ++i) { if (c[i] == '\n') ++count ; } } return count ; } finally { is.close() ; } } } </code></pre> <p>The Entries (links) creator:</p> <pre><code>public class Entries { public String entry ; public Entries nextEntry; // Empty Link Constructor public Entries () { } //Link constructor public Entries(String entryIn) { entry = entryIn ; nextEntry = null ; } public String getEntry () { return entry ; } public void setEntry (String entryIn) { entry = entryIn ; } public Entries getNext () { return nextEntry ; } public void setNext (Entries nextEntryIn) { nextEntry = nextEntryIn ; } //Print Link data public void printLink() { System.out.println("") ; System.out.print(getEntry() +"\n"); System.out.println("") ; } } </code></pre> <p>And the almighty Insertion sort class:</p> <pre><code>public class Insertion { public String Sort (EntriesList list) { } } </code></pre>
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    1. COYou should change the title to "How to implement insertion sort in Java?" :) Try following link http://www.roseindia.net/java/beginners/arrayexamples/InsertionSort.shtml
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      1. POHow to implement Insertion Sort?
      1. USAdriano Repetti
    2. COHow exactly should i modify this so it sorts string?
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