Question

COMP Help (Java): Can someone please help me with this problem! Someone answered it but it was wrong.

1. Create an ExtArrayList<E> class by extending the ArrayListE> class to include the following methods and estimate the run-time complexity of each method.

1. public ExtArrayList<E> append(ExtArrayList<E> ea)
   // appends the values in ea to the end of this ExtArrayList and returns the new ExtArrayList //example: this: {1,2,3} parameter : {4,5}, result {1,2,3,4,5}
2. public boolean consecutivePair(E e1, E e2)
   // checks if this ExtArrayList has two consecutive elements that are equal to e1 and e2 from the //beginning to the end of the list in that order and returns true, otherwise returns false. You can //assume the existence of an appropriately defined equals() method.
   // you need to handle errors for different situations.

Answer 1

ExtArrayList.java

import java.util.ArrayList;

/**
*
* @author owner
* @param <E>
*/
public class ExtArrayList<E> extends ArrayList<E> {
  
// appends the values in ea to the end of this ExtArrayList and returns the new ExtArrayList
//example: this: {1,2,3} parameter : {4,5}, result {1,2,3,4,5}
public ExtArrayList<E> append(ExtArrayList<E> ea){
ExtArrayList<E> result;
result = new ExtArrayList<>();

///append all elements of this(calling objects) list into result list
for (E obj:this)
{   
result.add(obj);
}   
///append all elements of list ea(passed as argument)into result list
for (E obj:ea)
{   
result.add(obj);
}   
return result;
}////ends append
  
//checks if this ExtArrayList has two consecutive elements that are equal to e1 and e2 from the
//beginning to the end of the list in that order and returns true, otherwise returns false.
public boolean consecutivePair(E e1, E e2){
///iterate from first element to second last element of this calling objects list
for(int i=0;i<this.size()-1;i++){
//if the current i element is matched with e1
//then check if i+1 th element is matches with e2
if(this.get(i).equals(e1)){
if(this.get(i+1).equals(e2)){
return true;
}
}
//if the current i element is matched with e2
//then check if i+1 th element is matches with e1
else if(this.get(i).equals(e2)){
if(this.get(i+1).equals(e1)){
return true;
}
}
}
//no match found
return false;
}

///function to print this list in format --> { 1 2 3 }
public void print(){
System.out.print("{ ");
for (int i=0;i<this.size();i++)
{
System.out.print(this.get(i)+" ");
}
System.out.println("}");

}
public static void main(String[] args) {

  
ExtArrayList<Integer> list1=new ExtArrayList<>();
ExtArrayList<Integer> list2=new ExtArrayList<>();
list1.add(1);
list1.add(2);
list1.add(2);
list1.add(3);
System.out.print("list1 =");
list1.print();
list2.add(4);
list2.add(5);
System.out.print("list2 =");
list2.print();
ExtArrayList<Integer> result=list1.append(list2);
System.out.print("result =");
result.print();
  
System.out.println("<2,3> in list1 ="+list1.consecutivePair(2,3));
System.out.println("<1,2> in list1 ="+list1.consecutivePair(1,2));
System.out.println("<2,1> in list1 ="+list1.consecutivePair(2,1));
System.out.println("<3,2> in list1 ="+list1.consecutivePair(3,2));
System.out.println("<1,3> in list1 ="+list1.consecutivePair(1,3));
System.out.println("<3,1> in list1 ="+list1.consecutivePair(3,1));
}

}

OUTPUT