1 /* 2 * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 class Parent { 25 int get() {return 1;} 26 } 27 28 class Child extends Parent { 29 int get() {return 2;} 30 int dummy() { 31 // When Child is linked during dynamic dump (when the VM is shutting 32 // down), it will be verified, which will recursively cause Child2/Parent2 33 // to be loaded and verified. 34 // We want to make sure that this is done at a point in the VM lifecycle where 35 // it's still safe to do so. 36 Parent2 x = new Child2(); 37 return x.get(); 38 } 39 } 40 41 class Parent2 { 42 int get() {return 3;} 43 } 44 45 class Child2 extends Parent2 { 46 int get() {return 4;} 47 } 48 49 class MyShutdown extends Thread{ 50 public void run(){ 51 System.out.println("shut down hook invoked..."); 52 } 53 } 54 55 class LinkClassApp { 56 public static void main(String args[]) { 57 Runtime r=Runtime.getRuntime(); 58 r.addShutdownHook(new MyShutdown()); 59 60 if (args.length > 0 && args[0].equals("run")) { 61 System.out.println("test() = " + test()); 62 } else { 63 // Executed during dynamic dumping. 64 System.out.println("Test.class is initialized."); 65 System.out.println("Parent.class and Child.class are loaded when Test.class is verified,"); 66 System.out.println("but these two classes are not linked"); 67 } 68 69 if (args.length > 0 && args[0].equals("callExit")) { 70 System.exit(0); 71 } 72 } 73 74 static int test() { 75 // Verification of Test.test() would load Child and Parent, and create a verification constraint that 76 // Child must be a subtype of Parent. 77 // 78 // Child and Parent are not linked until Test.test() is actually executed. 79 Parent x = new Child(); 80 return x.get(); 81 } 82 }