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Start your free trialHerman Vicens
12,540 PointsError moving elements from a List to a Set.
I am trying to move the elements of a List to a Set and I get this error:
java.lang.UnsupportedOperationException at java.util.AbstractList.add(AbstractList.java:148) at java.util.AbstractList.add(AbstractList.java:108) at java.util.AbstractCollection.addAll(AbstractCollection.java:344) at com.example.model.Course.addTags(Course.java:23) at JavaTester.run(JavaTester.java:96) at JavaTester.main(JavaTester.java:43)
Is there any other way to accomplish this move?
package com.example.model;
import java.util.Set;
import java.util.HashSet;
import java.util.List;
import java.util.ArrayList;
public class Course {
private String mTitle;
private Set<String> mTags;
public Course(String title) {
mTitle = title;
mTags = new HashSet<String>();
}
public void addTag(String tag) {
mTags.add(tag);
}
public void addTags(List<String> tags) {
tags.addAll(mTags) ; //Copy all elements of a List<String> to a HashSet<String>
}
public boolean hasTag(String tag) {
// TODO: Return whether or not the tag has been added
return false;
}
public String getTitle() {
return mTitle;
}
}
2 Answers
jose rodriguez
16,524 Pointsyour code has tags.addAll(mTags);
its should be mTags.addAll(tags);
Anders Björkland
7,481 PointsHi Herman,
It appears you are trying to add a Set to the List parameter that is in your addTags-method, instead of the other way around.