How to solve error "The constructor Pair<String,Integer>(String, int) is undefined"-CodePudding

I have this simple Pair class that I have made, and whenever I call the main method I get an error message saying that: "Exception in thread "main" java.lang.Error: Unresolved compilation problem: The constructor Pair<String,Integer>(String, int) is undefined"

Which is weird as I have defined the consturctor.

public class Pair<K, V> {
  K key;
  V value;
  
  public void set(K k, V v) {
    key = k;
    value = v;
  }
  
  public K getKey() { return key; }
  public V getValue() { return value; }
  public String toString() {
    return "["   getKey()   ", "   getValue()   "]";
  }
  
  public static <T> void reverse(Pair<T,T> p) {
      p.set(p.getValue(), p.getKey());
  }
      
  public static void main (String[] args) {
  
      Pair<String, Integer> pairA = new Pair<String, Integer>("abc",1);

      
      
  }
}

CodePudding user response：

You are missing a constructor:

public Pair(K k, V v) { ... }

Or you should do

Pair<String, Integer> pairA = new Pair<>();
pairA.set("abc", 1);

Notice you can use the "diamond" operator <> saving typing.

CodePudding user response：

You need to use an Integer instead of an int in the construction of pairA, e.g. Pair<String, Integer> pairA = new Pair<String, Integer>("abc",new Integer(1));