comparing elements of two arrayList in java

Question

i got two String type arraylist ..one list containing “book1”, “book2”, “book3” and “book4”. And another arrayList contains “book1”, “book2”, “book3”. So, size of first list is 4 and second is 3. And I created another arrayList equal to the size of first list

List<Integer> comparingList = new ArrayList<Integer>();
                    //adding default values as one
                    for(int a=0;a<firstList.size();a++){
                        comparingList.add(0);

                    }

And if any content is equal between two lists, I’m setting 1 instead of 0.

so the new arrayList(comparingList) should have 1,1,1,0 elements

for(int counter = 0;counter < firstList.size();counter++){
for(int counter1 = 0;counter1 < secondList.size();counter1++){
if(firstList.get(counter).equals(secondList.get(counter1))){
    comparingList.set(counter,1);
    break;
}
}

}

but when i do this, i’m not being able to set 1 as I can’t get into if condition, can anyone help me please

Answer 1

Only iterate on first arraylist with larger length and check for contains in second arraylist , if found set one else do nothing

for(int counter = 0; counter < firstList.size(); counter++) {
    if(secondList.contains(firstList.get(counter))) {
          comparingList.set(counter,1);
      }
  }

---

Whole java program

Just try to run the below program in http://www.compileonline.com/compile_java_online.php

import java.util.ArrayList;
import java.util.List;

public class CompareArrayListTest{

 public static void main(String[] args) {

    ArrayList<String> firstList = new ArrayList<String>();

    firstList.add("book1");
    firstList.add("book2");
    firstList.add("book3");
    firstList.add("book4");

    ArrayList<String> secondList = new ArrayList<String>();

    secondList.add("book1");
    secondList.add("book2");
    secondList.add("book3");

    List<Integer> comparingList = new ArrayList<Integer>();
    // adding default values as one
    for (int a = 0; a < firstList.size(); a++) {
        comparingList.add(0);

    }

    for (int counter = 0; counter < firstList.size(); counter++) {
        if (secondList.contains(firstList.get(counter))) {
            comparingList.set(counter, 1);
        }
    }

    System.out.println(comparingList);

}

---

BitSet bitset = new BitSet();
// adding default values as one
for (int a = 0; a < firstList.size(); a++) {
    comparingList.add(0);

}

for (int counter = 0; counter < firstList.size(); counter++) {
    for (int counter2 = 0; counter < secondList.size(); counter++) {
        if (secondList.get(counter2).equals(firstList.get(counter))) {
            bitset.set(counter, 1);
        }
    }
}