Guava - Joiner

import org.junit.Test;

import com.google.common.base.Joiner;

public class Collections {

 @Test
 public void Joiner_on_list_with_one_null_value() {
  
  String actual 
   = Joiner
    .on(",")
    .skipNulls()
    .join("one",null,"two");
  
  assertEquals("one,two", actual);
 }
 
 @Test
 public void Joiner_on_map() {
  
  Map map = new HashMap();
  map.put("k1", "v1");
  map.put("k2", "v2");

  String actual 
   = Joiner
    .on(",")
    .withKeyValueSeparator(" => ")
    .join(map);
  
  assertEquals("k1 => v1,k2 => v2", actual);
 }

}