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  1. import java.io.ByteArrayInputStream;
  2. import java.io.IOException;
  3. import java.io.ObjectInputStream;
  4. import java.io.Serializable;
  5.  
  6. public class Main {
  7.     public static void main(String[] args) throws IOException, ClassNotFoundException {
  8.         SerializableSingleton singleton = SerializableSingleton.INSTANCE;
  9.  
  10.         String data = "’\0\5sr\0\25SerializableSingleton\0\0\0\0\0\0\0\1\2\0\1L\0\1at\0\10"
  11.             + "LSneaky;xpsr\0\6SneakyOÎæJ&r\234©\2\0\1L\0\1rt\0\27LSerializableSingleton;xpq\0~\0\2";
  12.         try(ByteArrayInputStream baos = new ByteArrayInputStream(data.getBytes("iso-8859-1"));
  13.             ObjectInputStream oos = new ObjectInputStream(baos)) {
  14.             SerializableSingleton official = (SerializableSingleton)oos.readObject();
  15.  
  16.             System.out.println(official+"\t"+(official == singleton));
  17.             Object inofficial = Sneaky.instance.r;
  18.             System.out.println(inofficial+"\t"+(inofficial == singleton));
  19.         }
  20.     }
  21.  
  22. }
  23. class Sneaky implements Serializable {
  24.     static Sneaky instance;
  25.  
  26.     SerializableSingleton r;
  27.  
  28.     Sneaky(SerializableSingleton s) {
  29.         r = s;
  30.     }
  31.  
  32.     private Object readResolve() {
  33.         return instance = this;
  34.     }
  35. }
  36. class SerializableSingleton implements Serializable {
  37.     public static final SerializableSingleton INSTANCE = new SerializableSingleton();
  38.     private static final long serialVersionUID = 1L;
  39.  
  40.     private SerializableSingleton() {
  41.         System.out.println("SerializableSingleton initialized");
  42.     }
  43.     protected Object readResolve() {
  44.         System.out.println("replacing "+this+" with "+INSTANCE);
  45.         return INSTANCE;
  46.     }
  47. }
  48.  
Success #stdin #stdout 0.18s 38388KB
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stdin
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Standard input is empty
stdout
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SerializableSingleton initialized
replacing SerializableSingleton@255316f2 with SerializableSingleton@41906a77
SerializableSingleton@41906a77	true
SerializableSingleton@255316f2	false
https://ideone.com/08RgP1
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
public

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