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Java example source code file (TestPlainArrayNotGeneric.java)

This example Java source code file (TestPlainArrayNotGeneric.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

class, constructor, exception, genericarraytype, list, method, object, parameterizedtype, reflection, string, testplainarraynotgeneric, type, typevariable, util, wildcardtype

The TestPlainArrayNotGeneric.java Java example source code

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 5041784
 * @summary Check that plain arrays like String[] are never represented as
 * GenericArrayType.
 * @author Eamonn McManus
 */

import java.lang.reflect.Constructor;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class TestPlainArrayNotGeneric {
    public String[] m1(List<String> p1) {return null;}
    public List<String> m2(String[] p1) {return null;}
    public void m3(List<String> p1, String[] p2) {}
    public void m4(List<String[]> p1) {}
    public TestPlainArrayNotGeneric(List<String[]> p1) {}
    public TestPlainArrayNotGeneric(List<String> p1, String[] p2) {}

    public <T extends List T m5(T p1) {return null;}
    public <T extends Object> T[] m6(T[] p1, List p2) {return null;}

    public List<? extends Object[]> m6(List p1) {return null;}
    public <T extends List T m7(T[] p1) {return null;}
    public List<? super Object[]> m8(List p1) {return null;}
    public <T extends List T[] m9(T[] p1) {return null;}

    public static interface XMap extends Map<List {}
    public static interface YMap<K extends List
            extends Map<K[], V[]> {}


    private static String lastFailure;
    private static int failureCount;

    public static void main(String[] args) throws Exception {
        checkClass(TestPlainArrayNotGeneric.class);

        if (failureCount == 0)
            System.out.println("TEST PASSED");
        else
            throw new Exception("TEST FAILED: Last failure: " + lastFailure);
    }

    private static void checkClass(Class<?> c) throws Exception {
        Method[] methods = c.getMethods();
        for (Method m : methods) {
            check(m.getGenericReturnType(), "return type of method " + m);
            check(m.getGenericParameterTypes(), "parameter", "method " + m);
            check(m.getTypeParameters(), "type parameter", "method " + m);
        }

        Constructor[] constructors = c.getConstructors();
        for (Constructor constr : constructors) {
            check(constr.getGenericParameterTypes(), "parameter",
                    "constructor " + constr);
            check(constr.getTypeParameters(), "type parameter",
                    "constructor " + constr);
        }

        Class<?>[] inners = c.getDeclaredClasses();
        for (Class inner : inners)
            checkClass(inner);
    }

    private static void check(Type[] types, String elementKind, String what) {
        for (int i = 0; i < types.length; i++) {
            Type t = types[i];
            check(t, elementKind + " " + (i+1) + " of " + what);
        }
    }

    private static final Set<Type> checking = new HashSet<>();

    private static void check(Type t, String what) {
        if (t == null || !checking.add(t))
            return;
        // Avoid infinite recursion.  t can be null e.g. for superclass of Object.
        try {
            check2(t, what);
        } finally {
            checking.remove(t);
        }
    }

    private static void check2(Type t, String what) {
        if (t instanceof ParameterizedType) {
            ParameterizedType pt = (ParameterizedType) t;
            check(pt.getActualTypeArguments(), "type argument", what);
        } else if (t instanceof TypeVariable) {
            TypeVariable<?> tv = (TypeVariable) t;
            check(tv.getBounds(), "bound", what);
            GenericDeclaration gd = tv.getGenericDeclaration();
            if (gd instanceof Type)
                check((Type) gd, "declaration containing " + what);
        } else if (t instanceof WildcardType) {
            WildcardType wt = (WildcardType) t;
            check(wt.getLowerBounds(), "lower bound", "wildcard type in " + what);
            check(wt.getUpperBounds(), "upper bound", "wildcard type in " + what);
        } else if (t instanceof Class<?>) {
            Class<?> c = (Class) t;
            check(c.getGenericInterfaces(), "superinterface", c.toString());
            check(c.getGenericSuperclass(), "superclass of " + c);
            check(c.getTypeParameters(), "type parameter", c.toString());
        } else if (t instanceof GenericArrayType) {
            GenericArrayType gat = (GenericArrayType) t;
            Type comp = gat.getGenericComponentType();
            if (comp instanceof Class) {
                fail("Type " + t + " uses GenericArrayType when plain " +
                        "array would do, in " + what);
            } else
                check(comp, "component type of " + what);
        } else {
            fail("TEST BUG: mutant Type " + t + " (a " + t.getClass().getName() + ")");
        }
    }

    private static void fail(String why) {
        System.out.println("FAIL: " + why);
        lastFailure = why;
        failureCount++;
    }
}

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