/*******************************************************************************
* Companion code for the book "Introduction to Software Design with Java",
* 2nd edition by Martin P. Robillard.
*
* Copyright (C) 2022 by Martin P. Robillard
*
* This code is licensed under a Creative Commons
* Attribution-NonCommercial-NoDerivatives 4.0 International License.
*
* See http://creativecommons.org/licenses/by-nc-nd/4.0/
*
*******************************************************************************/
package e2.chapter9;
import java.util.function.Consumer;
/**
* Demonstrates how to use the Consumer interface to process card in the context
* of CardSource decorator
*
* See Section 9.4
*/
public class ConsumingDecorator implements CardSource {
private final CardSource aSource;
private final Consumer<Card> aCardConsumer;
/**
* Illustrates how to create a decorated card source
* that prints every card drawn to the console.
*/
public static void main(String[] args) {
ConsumingDecorator source = new ConsumingDecorator(new Deck(), System.out::println);
source.draw();
source.draw();
source.draw();
}
public ConsumingDecorator(CardSource pSource, Consumer<Card> pCardConsumer) {
aSource = pSource;
aCardConsumer = pCardConsumer;
}
public Card draw() {
Card card = aSource.draw();
aCardConsumer.accept(card);
return card;
}
public boolean isEmpty() {
return aSource.isEmpty();
}
}
String
class represents character strings. All
string literals in Java programs, such as "abc"
, are
implemented as instances of this class.
String
class represents character strings. All
string literals in Java programs, such as "abc"
, are
implemented as instances of this class.
Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String objects are immutable they can be shared. For example:
String str = "abc";
is equivalent to:
char data[] = {'a', 'b', 'c'}; String str = new String(data);
Here are some more examples of how strings can be used:
System.out.println("abc"); String cde = "cde"; System.out.println("abc" + cde); String c = "abc".substring(2, 3); String d = cde.substring(1, 2);
The class String
includes methods for examining
individual characters of the sequence, for comparing strings, for
searching strings, for extracting substrings, and for creating a
copy of a string with all characters translated to uppercase or to
lowercase. Case mapping is based on the Unicode Standard version
specified by the Character
class.
The Java language provides special support for the string concatenation operator ( + ), and for conversion of other objects to strings. For additional information on string concatenation and conversion, see The Java Language Specification.
Unless otherwise noted, passing a null
argument to a constructor
or method in this class will cause a NullPointerException
to be
thrown.
A String
represents a string in the UTF-16 format
in which supplementary characters are represented by surrogate
pairs (see the section Unicode
Character Representations in the Character
class for
more information).
Index values refer to char
code units, so a supplementary
character uses two positions in a String
.
The String
class provides methods for dealing with
Unicode code points (i.e., characters), in addition to those for
dealing with Unicode code units (i.e., char
values).
Unless otherwise noted, methods for comparing Strings do not take locale
into account. The Collator
class provides methods for
finer-grain, locale-sensitive String comparison.
javac
compiler
may implement the operator with StringBuffer
, StringBuilder
,
or java.lang.invoke.StringConcatFactory
depending on the JDK version. The
implementation of string conversion is typically through the method toString
,
defined by Object
and inherited by all classes in Java.System
class contains several useful class fields
and methods. It cannot be instantiated.
Among the facilities provided by the System
class
are standard input, standard output, and error output streams;
access to externally defined properties and environment
variables; a means of loading files and libraries; and a utility
method for quickly copying a portion of an array.System
class contains several useful class fields
and methods. It cannot be instantiated.
Among the facilities provided by the System
class
are standard input, standard output, and error output streams;
access to externally defined properties and environment
variables; a means of loading files and libraries; and a utility
method for quickly copying a portion of an array.Consumer
is expected
to operate via side-effects.
Consumer
is expected
to operate via side-effects.
This is a functional interface
whose functional method is accept(Object)
.