What is the equivalent of the C++ Pair in Java?

Question

Is there a good reason why there is no Pair in Java? What would be the equivalent of this C++ construct? I would rather avoid reimplementing my own.<

Answer 1

Another way to implement Pair with.

• Public immutable fields, i.e. simple data structure.
• Comparable.
• Simple hash and equals.

• Simple factory so you don't have to provide the types. e.g. Pair.of("hello", 1);

  public class Pair implements Comparable> {
  
      public final FIRST first;
      public final SECOND second;
  
      private Pair(FIRST first, SECOND second) {
          this.first = first;
          this.second = second;
      }
  
      public static  Pair of(FIRST first,
              SECOND second) {
          return new Pair(first, second);
      }
  
      @Override
      public int compareTo(Pair o) {
          int cmp = compare(first, o.first);
          return cmp == 0 ? compare(second, o.second) : cmp;
      }
  
      // todo move this to a helper class.
      private static int compare(Object o1, Object o2) {
          return o1 == null ? o2 == null ? 0 : -1 : o2 == null ? +1
                  : ((Comparable) o1).compareTo(o2);
      }
  
      @Override
      public int hashCode() {
          return 31 * hashcode(first) + hashcode(second);
      }
  
      // todo move this to a helper class.
      private static int hashcode(Object o) {
          return o == null ? 0 : o.hashCode();
      }
  
      @Override
      public boolean equals(Object obj) {
          if (!(obj instanceof Pair))
              return false;
          if (this == obj)
              return true;
          return equal(first, ((Pair) obj).first)
                  && equal(second, ((Pair) obj).second);
      }
  
      // todo move this to a helper class.
      private boolean equal(Object o1, Object o2) {
          return o1 == null ? o2 == null : (o1 == o2 || o1.equals(o2));
      }
  
      @Override
      public String toString() {
          return "(" + first + ", " + second + ')';
      }
  }