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2010-06-01T06:36:01Z

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в 18:01, 31 мая 2010

2010-05-31T18:01:44Z

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== Calling constructors with this ==



<source lang="java">
// : c04:Flower.java
// Calling constructors with "this."
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class Flower {
int petalCount = 0;
String s = new String("null");
Flower(int petals) {
petalCount = petals;
System.out.println("Constructor w/ int arg only, petalCount= "
+ petalCount);
}
Flower(String ss) {
System.out.println("Constructor w/ String arg only, s=" + ss);
s = ss;
}
Flower(String s, int petals) {
this(petals);
//! this(s); // Can"t call two!
this.s = s; // Another use of "this"
System.out.println("String & int args");
}
Flower() {
this("hi", 47);
System.out.println("default constructor (no args)");
}
void print() {
//! this(11); // Not inside non-constructor!
System.out.println("petalCount = " + petalCount + " s = " + s);
}
public static void main(String[] args) {
Flower x = new Flower();
x.print();
}
} ///:~

</source>



== Simple use of the this keyword ==



<source lang="java">

// : c04:Leaf.java
// Simple use of the "this" keyword.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class Leaf {
int i = 0;
Leaf increment() {
i++;
return this;
}
void print() {
System.out.println("i = " + i);
}
public static void main(String[] args) {
Leaf x = new Leaf();
x.increment().increment().increment().print();
}
} ///:~

</source>



== This shows off the uses of this ==



<source lang="java">
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/

// This shows off the uses of "this". It is a non-public class
// just so the file name UseThis doesn"t have to be the class name
// (some students found "This" in the class name confusing in this example).
public class MyClass {
final static int MAXX=640, MAXY=480; // low-res (VGA)
int x, y; // current location
/** Construct a MyClass with x and y values */
MyClass(int x, int y) {
this.x = x;
this.y = y;
}
/** Construct a MyClass with default values */
MyClass() {
this(MAXX/2, MAXY/2); // Use the constructor above
}
public String toString() {
return "[" + x + "," + y + "]";
}
/** Test main program */
public static void main(String[] av) {
System.out.println(new MyClass(300,100));
System.out.println(new MyClass());
}
}

</source>

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Admin: 1 версия

в 18:01, 31 мая 2010