/* 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
{
{
// your code goes here
Map
<String, String
> test
= new HashMap
<>();
test.put("1", "a");
test.put(null, "2");
System.
out.
println(test.
get(null)); System.
out.
println(test.
get("4")); }
}
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