1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 import java.lang.ref.WeakReference; 18 19 /** 20 * Some finalizer tests. 21 * 22 * This only works if System.runFinalization() causes finalizers to run 23 * immediately or very soon. 24 */ 25 public class Main { snooze(int ms)26 private static void snooze(int ms) { 27 try { 28 Thread.sleep(ms); 29 } catch (InterruptedException ie) { 30 System.out.println("Snooze: " + ie.getMessage()); 31 } 32 } 33 makeRef()34 public static WeakReference makeRef() { 35 /* 36 * Make ft in another thread, so there is no danger of 37 * a conservative reference leaking onto the main thread's 38 * stack. 39 */ 40 41 final WeakReference[] wimp = new WeakReference[1]; 42 Thread t = new Thread() { 43 public void run() { 44 FinalizerTest ft = new FinalizerTest("wahoo"); 45 wimp[0] = new WeakReference(ft); 46 ft = null; 47 } 48 }; 49 50 t.start(); 51 52 try { 53 t.join(); 54 } catch (InterruptedException ie) { 55 throw new RuntimeException(ie); 56 } 57 58 return wimp[0]; 59 } 60 wimpString(final WeakReference wimp)61 public static String wimpString(final WeakReference wimp) { 62 /* 63 * Do the work in another thread, so there is no danger of a 64 * conservative reference to ft leaking onto the main thread's 65 * stack. 66 */ 67 68 final String[] s = new String[1]; 69 Thread t = new Thread() { 70 public void run() { 71 Object ref = wimp.get(); 72 if (ref != null) { 73 s[0] = ref.toString(); 74 } 75 } 76 }; 77 78 t.start(); 79 80 try { 81 t.join(); 82 } catch (InterruptedException ie) { 83 throw new RuntimeException(ie); 84 } 85 86 return s[0]; 87 } 88 main(String[] args)89 public static void main(String[] args) { 90 WeakReference wimp = makeRef(); 91 92 System.out.println("wimp: " + wimpString(wimp)); 93 94 /* this will try to collect and finalize ft */ 95 System.out.println("gc"); 96 System.gc(); 97 98 System.out.println("wimp: " + wimpString(wimp)); 99 System.out.println("finalize"); 100 System.runFinalization(); 101 System.out.println("wimp: " + wimpString(wimp)); 102 103 System.out.println("sleep"); 104 snooze(1000); 105 106 System.out.println("reborn: " + FinalizerTest.mReborn); 107 System.out.println("wimp: " + wimpString(wimp)); 108 System.out.println("reset reborn"); 109 System.gc(); 110 FinalizerTest.mReborn = FinalizerTest.mNothing; 111 System.out.println("gc + finalize"); 112 System.gc(); 113 System.runFinalization(); 114 115 System.out.println("sleep"); 116 snooze(1000); 117 118 System.out.println("reborn: " + FinalizerTest.mReborn); 119 System.out.println("wimp: " + wimpString(wimp)); 120 } 121 } 122