Mega Code Archive
Reconstructing an externalizable object
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// : c12:Blip3.java
// Reconstructing an externalizable object.
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
public class Blip3 implements Externalizable {
private int i;
private String s; // No initialization
public Blip3() {
System.out.println("Blip3 Constructor");
// s, i not initialized
}
public Blip3(String x, int a) {
System.out.println("Blip3(String x, int a)");
s = x;
i = a;
// s & i initialized only in nondefault constructor.
}
public String toString() {
return s + i;
}
public void writeExternal(ObjectOutput out) throws IOException {
System.out.println("Blip3.writeExternal");
// You must do this:
out.writeObject(s);
out.writeInt(i);
}
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
System.out.println("Blip3.readExternal");
// You must do this:
s = (String) in.readObject();
i = in.readInt();
}
public static void main(String[] args) throws IOException,
ClassNotFoundException {
System.out.println("Constructing objects:");
Blip3 b3 = new Blip3("A String ", 47);
System.out.println(b3);
ObjectOutputStream o = new ObjectOutputStream(new FileOutputStream(
"Blip3.out"));
System.out.println("Saving object:");
o.writeObject(b3);
o.close();
// Now get it back:
ObjectInputStream in = new ObjectInputStream(new FileInputStream(
"Blip3.out"));
System.out.println("Recovering b3:");
b3 = (Blip3) in.readObject();
System.out.println(b3);
}
} ///:~
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