/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
        String s = null;
        switch(s)
        {
            case "a":
                System.out.println("a");
                break;
            case "b":
                System.out.println("b");
                break;
            default:
                System.out.println("default");
        }
	}
}

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