checker/tests/interning/StaticInternMethod.java

import java.util.HashMap;
import java.util.Map;
import org.checkerframework.checker.interning.qual.*;

public class StaticInternMethod {

  private static Map<Integer, @Interned Foo> pool = new HashMap<>();

  @SuppressWarnings("interning")
  public static @Interned Foo intern(Integer i) {
    if (pool.containsKey(i)) {
      return pool.get(i);
    }

    @Interned Foo f = new @Interned Foo(i);
    pool.put(i, f);
    return f;
  }

  static class Foo {
    public Foo(Integer i) {}
  }

  void test() {
    Integer i = 0;
    Foo f = new Foo(i);
    @Interned Foo g = intern(i);
  }
}