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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.lang.ref.*;
public class InternedString {
public static final String CONST = "Class InternedString";
public static void run() {
System.out.println("InternedString.run");
testImmortalInternedString();
testDeadInternedString();
}
private static WeakReference<String> makeWeakString() {
String s = "blah";
s = s + s;
WeakReference<String> strRef = new WeakReference<String>(s.intern());
return strRef;
}
private static void testDeadInternedString() {
WeakReference<String> strRef = makeWeakString();
System.gc();
// "blahblah" should disappear from the intern list
Main.assertTrue(strRef.get() == null);
}
private static void testImmortalInternedString() {
WeakReference strRef = new WeakReference<String>(CONST.intern());
System.gc();
// Class constant string should be entered to the interned table when
// loaded
Main.assertTrue(CONST == CONST.intern());
// and it should survive the gc
Main.assertTrue(strRef.get() != null);
String s = CONST;
// "Class InternedString" should remain on the intern list
strRef = new WeakReference<String>(s.intern());
// Kill s, otherwise the string object is still accessible from root set
s = "";
System.gc();
Main.assertTrue(strRef.get() == CONST);
}
}
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