deepcopy.java

来自「think in java TIJ-3rd-edition-code.zip」· Java 代码 · 共 73 行

//: appendixa:DeepCopy.java
// Cloning a composed object.
import com.bruceeckel.simpletest.*;

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(System.err);
    }
    return o;
  }
}

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(System.err);
    }
    return o;
  }
}

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(System.err);
    }
    // Must clone references:
    o.depth = (DepthReading)o.depth.clone();
    o.temperature = 
      (TemperatureReading)o.temperature.clone();
    return o; // Upcasts back to Object
  }
}

public class DeepCopy {
  public static void main(String[] args) {
    SimpleTest monitor =
      new SimpleTest("DeepCopy");
    OceanReading reading = 
      new OceanReading(33.9, 100.5);
    // Now clone it:
    OceanReading r = 
      (OceanReading)reading.clone();
    monitor.expect(new String[] {
    });
  }
} ///:~