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ArrayList trick

Posted on 2009-07-13
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Last Modified: 2013-12-29
I have two Strings .

d1="40-60-70"; // the data are id values basically

d2="60-70-80"; // the data are id values basically

I want to make an ArrayList with id's which are not present in d2 but in d1.

So, my expected output is ArrayList {"40"}


whats the easiest way to do this ?
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Question by:cofactor
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5 Comments
 
LVL 23

Assisted Solution

by:Ajay-Singh
Ajay-Singh earned 200 total points
ID: 24839573
You can use the following,
1. Split the string by "-", So you will get an array
2. Sort the array
3. Iterate over array to find out the missing element(s)
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LVL 20

Accepted Solution

by:
a_b earned 240 total points
ID: 24839585
1. Tokenize str1 and store in arrayList1
2. Tokenize str2 and store in arrayList2
3. for each token in arrayList1 check arrayList2.contains(token)
4. for each token in arrayList2 check arrayList1.contains(token)
5. Do processing accordingly
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LVL 1

Expert Comment

by:nitin22
ID: 24839598
Check if this helps!

import java.util.Set;
import java.util.TreeSet;
 
public class Main {
  public static <T> Set<T> union(Set<T> setA, Set<T> setB) {
    Set<T> tmp = new TreeSet<T>(setA);
    tmp.addAll(setB);
    return tmp;
  }
 
  public static <T> Set<T> intersection(Set<T> setA, Set<T> setB) {
    Set<T> tmp = new TreeSet<T>();
    for (T x : setA)
      if (setB.contains(x))
        tmp.add(x);
    return tmp;
  }
 
  public static <T> Set<T> difference(Set<T> setA, Set<T> setB) {
    Set<T> tmp = new TreeSet<T>(setA);
    tmp.removeAll(setB);
    return tmp;
  }
 
  public static <T> Set<T> symDifference(Set<T> setA, Set<T> setB) {
    Set<T> tmpA;
    Set<T> tmpB;
 
    tmpA = union(setA, setB);
    tmpB = intersection(setA, setB);
    return difference(tmpA, tmpB);
  }
 
  public static <T> boolean isSubset(Set<T> setA, Set<T> setB) {
    return setB.containsAll(setA);
  }
 
  public static <T> boolean isSuperset(Set<T> setA, Set<T> setB) {
    return setA.containsAll(setB);
  }
 
  public static void main(String args[]) {
    TreeSet<Character> set1 = new TreeSet<Character>();
    TreeSet<Character> set2 = new TreeSet<Character>();
 
    set1.add('A');
    set1.add('B');
    set1.add('C');
    set1.add('D');
 
    set2.add('C');
    set2.add('D');
    set2.add('E');
    set2.add('F');
 
    System.out.println("set1: " + set1);
    System.out.println("set2: " + set2);
 
    System.out.println("Union: " + union(set1, set2));
    System.out.println("Intersection: " + intersection(set1, set2));
    System.out.println("Difference (set1 - set2): " + difference(set1, set2));
    System.out.println("Symmetric Difference: " + symDifference(set1, set2));
 
    TreeSet<Character> set3 = new TreeSet<Character>(set1);
 
    set3.remove('D');
    System.out.println("set3: " + set3);
 
    System.out.println("Is set1 a subset of set2? " + isSubset(set1, set3));
    System.out.println("Is set1 a superset of set2? " + isSuperset(set1, set3));
    System.out.println("Is set3 a subset of set1? " + isSubset(set3, set1));
    System.out.println("Is set3 a superset of set1? " + isSuperset(set3, set1));
 
  }
}

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LVL 1

Expert Comment

by:nitin22
ID: 24839607
Your program will populate the sets by tokenizing the strings that you have.
0
 
LVL 8

Assisted Solution

by:ozlevanon
ozlevanon earned 160 total points
ID: 24840548
Here is a code to do that.
Note that the first list is created with new since Arrays.asList returns an immutable list, and we want to remove items from it.
			String d1="40-60-70"; // the data are id values basically
			String d2="60-70-80"; // the data are id values basically
			List<String> list1 = new ArrayList<String>(Arrays.asList(d1.split("-")));
			List<String> list2 = Arrays.asList(d2.split("-"));
			list1.removeAll(list2);

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