gistfile1.java

import java.util.stream.Stream;
import static java.util.stream.Collectors.toList;
import java.util.List;
import java.util.Arrays;
import com.google.common.collect.Lists;

// javac -classpath c:\java\m2\repository\com\google\guava\guava\17.0\guava-17.0.jar X.java
// java -classpath .;c:\java\m2\repository\com\google\guava\guava\17.0\guava-17.0.jar X

public class X {
	static class Pair<T1,T2> {
		private final T1 first;
		private final T2 second;
		public static <T1,T2> Pair<T1,T2> of(T1 first, T2 second) {
			return new Pair<T1,T2>(first,second);
		}
		private Pair(T1 first, T2 second) {
			this.first = first;
			this.second = second;
		}
		@Override
		public String toString() {
			String retval = String.format("(%s,%s)",first,second);
			return retval;
		}
	}
	public static void main(String... args) {
		List<String> list = Arrays.asList("D","A","G","I"); // assuming even size for simplicity
		List<Pair<?,?>> result = Lists.partition(list,2).stream().map(l -> Pair.of(l.get(0),l.get(1))).collect(toList());
		System.out.println(result); // [(D,A), (G,I)]
	}
}