Treeset error occured.How to solve that?

Question

TreeSet<String> t2= new TreeSet<String>();

t2.add("Pink");

t2.add("White");

t2.add("Black");

System.out.println("Tree set2: "+tree_set2);

t.addAll(t2);
System.out.println("Tree set1: "+t);

code ⤵️
https://code.sololearn.com/cICsLRcK86vd/?ref=app

Answer 1

line 35: System.out.println("Tree set2: "+t2);

Answer 2

thanks