Question

How to create a set of keys from TreeMap in Java

Answer 1

package javaapplication1;

import java.util.Iterator;
import java.util.Set;
import java.util.TreeMap;

public class JavaApplication1 {

    public static void main(String[] args) {

        TreeMap treeMap = new TreeMap();

        treeMap.put("1", "Java");
        treeMap.put("2", "C");
        treeMap.put("3", "C++");
        treeMap.put("5", "PHP");
        treeMap.put("4", "C#");
        treeMap.put("6", "JavaScript");
        
        Set st = treeMap.keySet();

        Iterator itr = st.iterator();
        while (itr.hasNext()) 
            System.out.println(itr.next());
    }
}
 
/*

run:

1
2
3
4
5
6

*/

 

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