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java HashMap keyset instance

Author：Eve Cole Update Time：2024-11-19 20:42:01

a simple example

Copy the code code as follows:

//a simple demo
import java.util.HashMap;
import java.util.Set;

public class TestHashMap {
public static void main(String[] args) {
HashMap<Integer, Integer> G = new HashMap<Integer,Integer>();
G.put(1, 1); G.put(2, 4);
G.put(3, 9); G.put(4, 16);
Set<Integer> set = G.keySet();
set.remove(3);
System.out.println(G.size());//print 3
}
}

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