PrivateLambdas.java

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/*
 * @test
 * @bug 8012557
 * @summary Check that 8012557 is fixed, that interface lambda
 *          methods are private
 * @author  Robert Field
 * @compile SAM.java
 * @compile A.java
 * @compile B.java
 * @compile C.java
 * @run main PrivateLambdas
 *
 * Unless the lambda methods are private, this will fail with:
 *  AbstractMethodError:
 *        Conflicting default methods: A.lambda$0 B.lambda$0 C.lambda$0
 */

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

interface X extends A, B, C {
   default String u() { return " "; }
   default String name() {
      return A.super.name() + B.super.name() + C.super.name();
   }
}

public class PrivateLambdas implements X {
   public static void main(String[] args) throws Exception {

      // Check that all the lambda methods are private instance synthetic
      for (Class<?> k : new Class<?>[] { A.class, B.class, C.class }) {
         Method[] methods = k.getDeclaredMethods();
         int lambdaCount = 0;
         for(Method m : methods) {
            if (m.getName().startsWith("lambda$")) {
               ++lambdaCount;
               int mod = m.getModifiers();
               if ((mod & Modifier.PRIVATE) == 0) {
                  throw new Exception("Expected " + m + " to be private");
               }
               if (!m.isSynthetic()) {
                  throw new Exception("Expected " + m + " to be synthetic");
               }
               if ((mod & Modifier.STATIC) != 0) {
                  throw new Exception("Expected " + m + " to be instance method");
               }
            }
         }
         if (lambdaCount == 0) {
            throw new Exception("Expected at least one lambda method");
         }
      }

      /*
       * Unless the lambda methods are private, this will fail with:
       *  AbstractMethodError:
       *        Conflicting default methods: A.lambda$0 B.lambda$0 C.lambda$0
       */
      X x = new PrivateLambdas();
      if (!x.name().equals(" A B C")) {
         throw new Exception("Expected ' A B C' got: " + x.name());
      }
   }
}