Cloning a composed object : Clone « Class « Java

1. Java
2. Class
3. Clone

Cloning a composed object

      

// : appendixa:DeepCopy.java
// Cloning a composed object.
// {Depends: junit.jar}
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.

import junit.framework.*;

class DepthReading implements Cloneable {
  private double depth;

  public DepthReading(double depth) {
    this.depth = depth;
  }

  public Object clone() {
    Object o = null;
    try {
      o = super.clone();
    } catch (CloneNotSupportedException e) {
      e.printStackTrace();
    }
    return o;
  }

  public double getDepth() {
    return depth;
  }

  public void setDepth(double depth) {
    this.depth = depth;
  }

  public String toString() {
    return String.valueOf(depth);
  }
}

class TemperatureReading implements Cloneable {
  private long time;

  private double temperature;

  public TemperatureReading(double temperature) {
    time = System.currentTimeMillis();
    this.temperature = temperature;
  }

  public Object clone() {
    Object o = null;
    try {
      o = super.clone();
    } catch (CloneNotSupportedException e) {
      e.printStackTrace();
    }
    return o;
  }

  public double getTemperature() {
    return temperature;
  }

  public void setTemperature(double temperature) {
    this.temperature = temperature;
  }

  public String toString() {
    return String.valueOf(temperature);
  }
}

class OceanReading implements Cloneable {
  private DepthReading depth;

  private TemperatureReading temperature;

  public OceanReading(double tdata, double ddata) {
    temperature = new TemperatureReading(tdata);
    depth = new DepthReading(ddata);
  }

  public Object clone() {
    OceanReading o = null;
    try {
      o = (OceanReading) super.clone();
    } catch (CloneNotSupportedException e) {
      e.printStackTrace();
    }
    // Must clone references:
    o.depth = (DepthReading) o.depth.clone();
    o.temperature = (TemperatureReading) o.temperature.clone();
    return o; // Upcasts back to Object
  }

  public TemperatureReading getTemperatureReading() {
    return temperature;
  }

  public void setTemperatureReading(TemperatureReading tr) {
    temperature = tr;
  }

  public DepthReading getDepthReading() {
    return depth;
  }

  public void setDepthReading(DepthReading dr) {
    this.depth = dr;
  }

  public String toString() {
    return "temperature: " + temperature + ", depth: " + depth;
  }
}

public class DeepCopy extends TestCase {
  public DeepCopy(String name) {
    super(name);
  }

  public void testClone() {
    OceanReading reading = new OceanReading(33.9, 100.5);
    // Now clone it:
    OceanReading clone = (OceanReading) reading.clone();
    TemperatureReading tr = clone.getTemperatureReading();
    tr.setTemperature(tr.getTemperature() + 1);
    clone.setTemperatureReading(tr);
    DepthReading dr = clone.getDepthReading();
    dr.setDepth(dr.getDepth() + 1);
    clone.setDepthReading(dr);
    assertEquals(reading.toString(), "temperature: 33.9, depth: 100.5");
    assertEquals(clone.toString(), "temperature: 34.9, depth: 101.5");
  }

  public static void main(String[] args) {
    junit.textui.TestRunner.run(DeepCopy.class);
  }
} ///:~


           
         
    
    
    
    
    
  

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