Question

Can anyone helps to create a Test.java for the following classes please? Where the Test.java will have a Scanner roster = new Scanner(new FileReader(“roster.txt”); will be needed in this main method to read the roster.txt.

public interface List {
   public int size();
   public boolean isEmpty();

   public Object get(int i) throws OutOfRangeException;

   public void set(int i, Object e) throws OutOfRangeException;

   public void add(int i, Object e) throws OutOfRangeException;

public Object remove(int i) throws OutOfRangeException;

   }

public class ArrayList implements List {
   private int CAP;
private int size;
private Object[] item;
public ArrayList(int capacity){
this.size = 0;
this.CAP = capacity;
this.item = new Object [capacity];
}
public ArrayList () {
this(100);
}
public int size(){
return size;
}
public boolean isEmpty(){
return size==0;
}
public Object get(int i) throws OutOfRangeException {
if (i<0 || i>=size)
throw new OutOfRangeException ("Out of Range");
return item [i];
}
public void set(int i, Object e) throws OutOfRangeException {
if (i<0 || i>=size)
throw new OutOfRangeException ("Out of Range");
item [i] = e;
}
public void add(int i, Object e) throws OutOfRangeException {
if (i<0 || i>size)
throw new OutOfRangeException ("Out of Range");
for (int j = size - 1; j>=i; j--)
item[j+1] = item [j];
size++;
}
public Object remove(int i) throws OutOfRangeException {
if (i<0 || i>=size)
throw new OutOfRangeException ("Out of Range");
Object answer = item[i];
for (int j=i; j<size-1; j++)
item[j] = item[j+1];
item[size-1] = null;
size--;
return answer;
}
}

public class OutOfRangeException extends Exception {
   public OutOfRangeException(String str){
       System.out.println("OutOfRangeException:" + str);}
       public OutOfRangeException (){
       this("Out Of Range");}
}

public abstract class AbstractMap {
   public abstract Object get(Object key);
   public abstract Object put(Object key, Object value);
   public abstract Object remove(Object key);
   public abstract boolean isEmpty();
   public abstract int size();
   public abstract Iterable keySet();
   }

import java.util.Iterator;
public class SArrayIterator implements Iterator {
   private ArrayList data;
   private int i = 0;
   private boolean removable = false;

   public SArrayIterator(ArrayList a) {
   data = a;
   }

   public boolean hasNext() {return i < data.size();}

   public Object next() {
   Object answer = null;
   if (i == data.size())
   return null;
   try {
   answer = data.get(i++);
   } catch (OutOfRangeException e) {
   System.out.println("Out Of Range");
   }
   removable = true;
   return answer;
   }

   public void remove() {
   if (!removable)
   throw new IllegalStateException("nothing to remove");
   try {
   data.remove(i-1);
   } catch (OutOfRangeException e) {
   System.out.println("Out of Range");
   }
   i--;
   removable = false;
   }
}

public class MapEntry {
private String key;
private String value;
public MapEntry() {this(null, null);}
public MapEntry(String key, String value) {
   key = key;
value = value;
}
public String getKey() {return key;}
public String getValue() {return value;}
public void setKey(String k) {key = k;}
public Object setValue(String value) {
   String old = this.getValue();
   this.value = value;
   return old;
}

public int hashCode () {
   if (key == null) return 0;
   int h = 0;
   for (int i = 0; i<key.length(); i++){
       h += (int)key.charAt(i);
       h = (h<<5) | (h>>>27);
   }
   return h;
}
}

import java.util.Random;
public abstract class AbstractHashMap extends AbstractMap {
protected int n = 0;
protected int capacity;
private int prime;
private long scale, offset;
public AbstractHashMap(int c, int p) {
   this.capacity = c;
   Random rand = new Random();
   this.scale = rand.nextInt(prime-1)+ 1;
   this.offset = rand.nextInt(prime);
   createTable();
}
public AbstractHashMap() { this(61,999331);}
public int size() {return n;}
public boolean isEmpty() {return n==0;}
private int hashValue(Object key) {
   return (int)((Math.abs(key.hashCode()*scale + offset) % prime) % capacity);}

public Object get(Object key) {
   int h = hashValue(key);
   return bucketGet(h, key);
  
}
public Object put (Object key, Object value) {
   int h = hashValue(key);
   return bucketPut(h, key);
}
public Object remove (Object key) {
   int h = hashValue(key);
   return bucketRemove(h,key);
}
protected abstract void createTable();
protected abstract Object bucketGet(int h, Object k);
protected abstract Object bucketPut(Object k, Object v);
protected abstract Object bucketRemove(int h, Object k);
}
import java.util.Iterator;
public class ProbeHashTable extends AbstractHashMap {  
   private MapEntry[] table;
   private MapEntry DEFUNCT = new MapEntry(null, null);

   private int ncollisions = 0;
   public ProbeHashTable() {super();}
   public ProbeHashTable(int cap,int p) {super(cap, p); }
   private boolean compareStr(String s, String t) {
       boolean result = s.equals(t);
       if (!result)
   ncollisions++;
   return result;
   }
   protected void createTable() {
   table = (MapEntry[]) new MapEntry[capacity]; }
     
   private boolean isAvailable(int i) {
   return (table[i] == null || table[i] == DEFUNCT);
   }
   private int findSlot(int h, String k) {
   int avail = -1;
   int i = h;
   do {
   if(isAvailable(i)) {
   if(avail == -1) avail = i;
   if(table[i] == null) break;
   }
   else if(compareStr(table[i].getKey(), k)) { return i;}
   i = (i + 1) % capacity;
   }
   while(i != h);
   return -(avail + 1);
   }
   protected Object bucketPut(int h, Object key, Object value) {
   int i = findSlot(h, (String) key);
   if(i >= 0)
   return table[i].setValue((String) value);
   table[-(i + 1)] = new MapEntry((String) key, (String) value);
   n++;
   return null;
   }
   protected Object bucketGet(int h, Object key) {
   int i = findSlot(h, (String) key);
   if(i < 0)
   return null;
   return table[i].getValue();
   }
   protected Object bucketRemove(int h, Object key) {
   int i = findSlot(h, (String) key);
   if(i < 0)
   return null;
   Object answer = table[i].getValue();
   table[i] = DEFUNCT;
   n--;
   return answer;
   }
   private class KeyIterable implements Iterable{

public Iterator iterator() {
   ArrayList buffer = new ArrayList(n);
   for(int i = 0; i < capacity; i++)
   try {
   if(!isAvailable(i))
   buffer.add(buffer.size(), table[i].getKey());
   }
   catch(OutOfRangeException e) {
   System.out.println("keySet: Out Of Range");
   }
   return new SArrayIterator(buffer);
   }
   }
   public Iterable keySet() {
   return new KeyIterable();
   }
   public int getCollisions(){
   return ncollisions;
   }
   public String toString() {
   String str = "";
   for (int i = 0; i < table.length; i++) {
   str += i + " " + table[i] + " " + table[i].getValue() + "\n";
   }
   return str;
   }

   }

Answer 1

Hi,

The problem has been resolved. A file named "Test.java" has been created with Scanner to read a file "roaster.txt". You haven't mentioned how you need to use the Test class and what is your task to perform so I have created a main test file to use for every purpose.

You can read a file line by line and put the data into ArrayList and other classes according to you. The test file has been tested on a random data that roster.txt file have.

Please refer to the screenshot that having the data of file and the code output. The line by line file data has been printed in output.

Screenshot:

Code:

---------------

import java.io.*;
import java.util.*;
public class Test
{
public static void main(String[] args) throws Exception
{

   Scanner sc = new Scanner(new File("roster.txt"));

   while (sc.hasNextLine())
       System.out.println(sc.nextLine());
   }
}

--------------

The problem has been resolved, I hope you will like the solution. If you have any question or query regarding this problem or other, please comment below and give the positive rating.

Thank You!! Happy Learning!! !!