73 lines
2.0 KiB
Java
73 lines
2.0 KiB
Java
// serialization/Blip3.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Reconstructing an externalizable object
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import java.io.*;
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public class Blip3 implements Externalizable {
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private int i;
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private String s; // No initialization
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public Blip3() {
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System.out.println("Blip3 Constructor");
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// s, i not initialized
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}
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public Blip3(String x, int a) {
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System.out.println("Blip3(String x, int a)");
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s = x;
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i = a;
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// s & i initialized only in non-zero-argument constructor.
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}
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@Override public String toString() { return s + i; }
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@Override public void writeExternal(ObjectOutput out)
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throws IOException {
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System.out.println("Blip3.writeExternal");
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// You must do this:
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out.writeObject(s);
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out.writeInt(i);
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}
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@Override public void readExternal(ObjectInput in)
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throws IOException, ClassNotFoundException {
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System.out.println("Blip3.readExternal");
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// You must do this:
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s = (String)in.readObject();
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i = in.readInt();
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}
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public static void main(String[] args) {
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System.out.println("Constructing objects:");
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Blip3 b3 = new Blip3("A String ", 47);
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System.out.println(b3);
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try(
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ObjectOutputStream o = new ObjectOutputStream(
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new FileOutputStream("Blip3.serialized"))
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) {
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System.out.println("Saving object:");
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o.writeObject(b3);
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} catch(IOException e) {
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throw new RuntimeException(e);
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}
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// Now get it back:
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System.out.println("Recovering b3:");
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try(
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ObjectInputStream in = new ObjectInputStream(
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new FileInputStream("Blip3.serialized"))
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) {
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b3 = (Blip3)in.readObject();
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} catch(IOException | ClassNotFoundException e) {
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throw new RuntimeException(e);
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}
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System.out.println(b3);
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}
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}
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/* Output:
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Constructing objects:
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Blip3(String x, int a)
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A String 47
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Saving object:
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Blip3.writeExternal
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Recovering b3:
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Blip3 Constructor
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Blip3.readExternal
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A String 47
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*/
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