Guava Null Treatmenat and use of Optional

App.java

package GauvaDemo;

import static com.google.common.base.Preconditions.*;
import com.google.common.base.*;
import java.util.ArrayList;
import java.util.List;

/**
 * Just a snippet on Optional and usage of Preconditions in Guava.
 *
 */
public class App {
    public static void main(String[] args) {
      Optional<String> returned = methodThatReturnsSomething(new ArrayList());
      if(!returned.isPresent())
          System.out.println("Rohit Not found");
      List<String> list = new ArrayList<String>();
        list.add("Rohit");
      returned = methodThatReturnsSomething(list);
      if(returned.isPresent())
          System.out.println("Rohit Found");
      foo(null);
    }

    static Optional<String> methodThatReturnsSomething(List<String> list){
        if(list.contains("Rohit"))
            return Optional.of("Rohit");
        else
            return Optional.absent();
    }

    static int foo(Integer bar){
        checkNotNull(bar);
        return bar;
    }
}