Question

3.6 Learning Objective: To insert a String into a ArrayList list and maintain the sort order of the list. Problem: Write a void method named insertName() that has two input parameters: (1) pList which is an object of ArrayList where each element of pList is a person's name; and (2) a String object named pName. Assume the names in pList are sorted into ascending order. The method shall insert pName into pList such that the sort order is maintained. The pList parameter variable will be non-null but the list itself may be empty.

Answer 1

import java.util.*;

public class MyClass {
static void insertName(List<String> pList,String pName)
{
int insertAt = Collections.binarySearch(pList, pName);
if (insertAt < 0)
{
insertAt = (insertAt * -1) - 1;
}

pList.add(insertAt, pName);
}
public static void main(String args[]) {
List<String> names = new ArrayList<String>(25);
names.add("A");
names.add("B");
names.add("D");

insertName(names,"C");

  
for (int index = 0; index < names.size(); index++)
{
String name = names.get(index);
System.out.println("[" + index + "] " + name);
}
}
}