Question

I have tried to remove the list from a vector like below.

public class StringVectorTest {

private final List<String> stringVector = new Vector<String>();

@Test
public void listRemoveTest(){

    List<String> list = stringVector.subList(0, 2);

    stringVector.removeAll(list);

    Assert.assertEquals(stringVector.size(), 3);
}

@Before
public void fillList(){
    stringVector.add("ABC");
    stringVector.add("DEF");
    stringVector.add("GEH");
    stringVector.add("IJK");
    stringVector.add("LMN");
}

}

while i run the test i am getting the below error

java.util.ConcurrentModificationException
at java.util.SubList.checkForComodification(AbstractList.java:752)
at java.util.SubList.listIterator(AbstractList.java:682)
at java.util.AbstractList.listIterator(AbstractList.java:284)
at java.util.SubList.iterator(AbstractList.java:678)
at java.util.AbstractCollection.contains(AbstractCollection.java:82)
at java.util.Collections$SynchronizedCollection.contains(Collections.java:1563)
at java.util.AbstractCollection.removeAll(AbstractCollection.java:336)
at java.util.Vector.removeAll(Vector.java:853)

I know that i have to use an Iterator to overcome this ConcurrentModificationException can anyone please let me know how i should use it in a efficient manner / best practice?

Thanks in advance.

Answer 1

Do it as below:

public void listRemoveTest() {
    stringVector.subList(0, 2).clear();
    Assert.assertEquals(stringVector.size(), 3);
}