compete.java

中文JAVA编程思想第二版,一本很好的JAVA入门书籍!

//: appendixa:Compete.java
// From 'Thinking in Java, 2nd ed.' by Bruce Eckel
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
import java.io.*;

class Thing1 implements Serializable {}
class Thing2 implements Serializable {
  Thing1 o1 = new Thing1();
}

class Thing3 implements Cloneable {
  public Object clone() {
    Object o = null;
    try {
      o = super.clone();
    } catch(CloneNotSupportedException e) {
      System.err.println("Thing3 can't clone");
    }
    return o;
  }
}

class Thing4 implements Cloneable {
  Thing3 o3 = new Thing3();
  public Object clone() {
    Thing4 o = null;
    try {
      o = (Thing4)super.clone();
    } catch(CloneNotSupportedException e) {
      System.err.println("Thing4 can't clone");
    }
    // Clone the field, too:
    o.o3 = (Thing3)o3.clone();
    return o;
  }
}

public class Compete {
  static final int SIZE = 5000;
  public static void main(String[] args) 
  throws Exception {
    Thing2[] a = new Thing2[SIZE];
    for(int i = 0; i < a.length; i++)
      a[i] = new Thing2();
    Thing4[] b = new Thing4[SIZE];
    for(int i = 0; i < b.length; i++)
      b[i] = new Thing4();
    long t1 = System.currentTimeMillis();
    ByteArrayOutputStream buf = 
      new ByteArrayOutputStream();
    ObjectOutputStream o =
      new ObjectOutputStream(buf);
    for(int i = 0; i < a.length; i++)
      o.writeObject(a[i]);
    // Now get copies:
    ObjectInputStream in =
      new ObjectInputStream(
        new ByteArrayInputStream(
          buf.toByteArray()));
    Thing2[] c = new Thing2[SIZE];
    for(int i = 0; i < c.length; i++)
      c[i] = (Thing2)in.readObject();
    long t2 = System.currentTimeMillis();
    System.out.println(
      "Duplication via serialization: " +
      (t2 - t1) + " Milliseconds");
    // Now try cloning:
    t1 = System.currentTimeMillis();
    Thing4[] d = new Thing4[SIZE];
    for(int i = 0; i < d.length; i++)
      d[i] = (Thing4)b[i].clone();
    t2 = System.currentTimeMillis();
    System.out.println(
      "Duplication via cloning: " +
      (t2 - t1) + " Milliseconds");
  }
} ///:~