carfield.com.hk

DDAluminum.java

2001-12-26T16:00:00Z

DDCardboard.java

2001-12-26T16:00:00Z

DDGlass.java

2001-12-26T16:00:00Z

DDPaper.java

2001-12-26T16:00:00Z

DDTrash.dat

2001-12-26T16:00:00Z

DoubleDispatch.java

2001-12-26T16:00:00Z

//: c12:doubledispatch:DoubleDispatch.java
// Using multiple dispatching to handle more
// than one unknown type during a method call.
import c12.trash.*;
import java.util.*;
import com.bruceeckel.test.*;

class AluminumBin extends TypedBin {
  public boolean add(DDAluminum a) {
    return addIt(a);
  }
}

class PaperBin extends TypedBin {
  public boolean add(DDPaper a) {
    return addIt(a);
  }
}

class GlassBin extends TypedBin {
  public boolean add(DDGlass a) {
    return addIt(a);
  }
}

class CardboardBin extends TypedBin {
  public boolean add(DDCardboard a) {
    return addIt(a);
  }
}

class TrashBinSet {
  private TypedBin[] binSet = {
    new AluminumBin(),
    new PaperBin(),
    new GlassBin(),
    new CardboardBin()
  };
  public void sortIntoBins(Collection bin) {
    Iterator e = bin.iterator();
    while(e.hasNext()) {
      TypedBinMember t = 
        (TypedBinMember)e.next();
      if(!t.addToBin(binSet))
        System.err.println("Couldn't add " + t);
    }
  }
  public TypedBin[] binSet() { return binSet; }
}

public class DoubleDispatch extends UnitTest {
  Collection bin = new ArrayList();
  TrashBinSet bins = new TrashBinSet();
  public DoubleDispatch() {
    // ParseTrash still works, without changes:
    ParseTrash.fillBin("DDTrash.dat", bin);
  }
  public void test() {
    // Sort from the master bin into 
    // the individually-typed bins:
    bins.sortIntoBins(bin);
    TypedBin[] tb = bins.binSet();
    // Perform sumValue for each bin...
    for(int i = 0; i < tb.length; i++)
      Trash.sumValue(tb[i].c.iterator());
    // ... and for the master bin
    Trash.sumValue(bin.iterator());
  }
  public static void main(String args[]) {
    new DoubleDispatch().test();
  }
} ///:~

TypedBin.java

2001-12-26T16:00:00Z

TypedBinMember.java

2001-12-26T16:00:00Z

makefile

2001-12-26T16:00:00Z

# From Thinking in Patterns (with Java) by Bruce Eckel
# At http://www.BruceEckel.com
# (c)2001 Bruce Eckel 
# Copyright notice in Copyright.txt
# Automatically-generated MAKEFILE 
# For examples in directory .\c12\doubledispatch
# using the JDK 1.3 compiler
# Invoke with: make

HOME := ../../

ifndef MAKECMDGOALS
MAKECMDGOALS := javac
endif

# Command.com is too weak to build this under Windows NT/2000:
ifeq ($(OS),Windows_NT)
COMSPEC=$(SYSTEMROOT)\system32\cmd.exe
endif

ifneq ($(MAKECMDGOALS),clean)
include $(HOME)/$(MAKECMDGOALS).mac
endif

.SUFFIXES : .class .java
.java.class :
	$(JVC) $(JVCFLAGS) $<

javac: \
	TypedBinMember.class \
	DDAluminum.class \
	DDPaper.class \
	DDGlass.class \
	DDCardboard.class \
	TypedBin.class \
	DoubleDispatch.class

jikes: \
	TypedBinMember.class \
	DDAluminum.class \
	DDPaper.class \
	DDGlass.class \
	DDCardboard.class \
	TypedBin.class \
	DoubleDispatch.class

clean:
ifeq ($(notdir $(SHELL)),COMMAND.COM)
	del *.class
else
	rm -f *.class
endif


TypedBinMember.class: TypedBinMember.java 

DDAluminum.class: DDAluminum.java 

DDPaper.class: DDPaper.java 

DDGlass.class: DDGlass.java 

DDCardboard.class: DDCardboard.java 

TypedBin.class: TypedBin.java 

DoubleDispatch.class: DoubleDispatch.java 
	$(JVC) $(JVCFLAGS) $<
	java com.bruceeckel.test.RunUnitTests DoubleDispatch