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============================================================================================
Learn More About Java2 Professional Tutrial Vol.1
I-ichirow Suzuki
============================================================================================
Learn More About Java2 Professional Tutrial
Chapter 1 変数とオブジェクト
Chapter 2 お約束とコメント
Chapter 3 メソッドと基本制御
Chapter 4 コンストラクタと初期化
Chapter 5 クラスの再利用
Chapter 6 継承
Chapter 7 ポリモフィズム
Chapter 8 インターフェイスとインナークラス
Chapter 9 コレクション
Chapter10 エラーハンドリング
Chapter11 ファイル入出力
Chapter12 Creating Windows AWT
Chapter13 Creating Windows Swing
Chapter14 Multiple Threads
Chapter15 ネットワーク
Chapter16 アルゴリズムとデータ構造
///////////////////////////////////////////////////////////////////////////////////////////
//// Chapter 1 変数とオブジェクト
//------------------------------------------------
// c01 どれも結局同じ意味
String s; s = "asdf" ;
String s = "asdf";
String s = new String("asdf");
//------------------------------------------------
// c01 どれも結局同じ意味
char c = 'x';
Character C = new Character(c);
Character C = new Character('x');
//------------------------------------------------
// c01 スコープとは
{
int x = 12;
/* only x available */
{
int q = 96;
/* both x & q available */
}
/* only x available */
/* q "out of scope" */
}
{
int x = 12;
{
int x = 96; /* illegal */
}
}
{
String s = new String("a string");
} /* end of scope */
//------------------------------------------------
// c01 クラスオブジェクトのインスタンス
// DataBase.java
class DataOnly
{
int i;
float f;
boolean b;
}
public class DataBase //ファイルに１つだけの存在のpublicクラス
{
public static void main(String[] args)
{
DataOnly d = new DataOnly();
d.i = 47;
d.f = 1.1f;
d.b = false;
}
}
//------------------------------------------------
// c01 メソッドの戻り型
returnType methodName( /* argument list */ )
{
/* Method body */
}
int storage(String s)
{
return s.length() * 2;
}
boolean flag()
{
return true;
}
float naturalLogBase()
{
return 2.718f;
}
void nothing()
{
return;
}
void nothing2() {}
//------------------------------------------------
// c01 staticとは
// StaticTest.java
class StaticTest
{
static int i = 47;
}
public class StaticTestBase
{
public static void main(String[] args)
{
StaticTest.i++;
}
}
//------------------------------------------------
// c01 staticとは 応用
// StaticFunBase.java
class StaticTest
{
static int i = 47;
}
class StaticFun
{
static void incr()
{
StaticTest.i++;
}
public class StaticFunBase
{
public static void main(String[] args)
{
StaticFun sf = new StaticFun();
sf.incr();
}
}
///////////////////////////////////////////////////////////////////////////////////////////
//// Chapter 2 お約束とコメント
//------------------------------------------------
// c02 Hello, world ?
// HelloDate.java
import java.util.*;
public class HelloDate
{
public static void main(String[] args)
{
System.out.println("Hello, it's: ");
System.out.println(new Date());
}
}
/**
Hello, it's:
Sat Feb 24 14:37:56 JST 2001
**/
//------------------------------------------------
// c02 コメント
/* This is a comment
* that continues
* across lines
*/
/* This is a comment that
continues across lines */
// this is a one-line comment
/** A class comment */
public class docTest
{
/** A variable comment */
public int i;
/** A method comment */
public void f() {}
}
///////////////////////////////////////////////////////////////////////////////////////////
//// Chapter 3 メソッドと基本制御
//------------------------------------------------
// オブジェクトの = は 同じメモリアドレスを参照させる 決して値の代入ではない
//: c03:Assignment.java
class Number
{
int i;
}
public class Assignment
{
public static void main(String[] args)
{
Number n1 = new Number();
Number n2 = new Number();
n1.i = 9;
n2.i = 47;
System.out.println("1: n1.i: " + n1.i + ", n2.i: " + n2.i);
n1 = n2;
System.out.println("2: n1.i: " + n1.i + ", n2.i: " + n2.i);
n1.i = 27;
System.out.println("3: n1.i: " + n1.i + ", n2.i: " + n2.i);
}
}
/**
1: n1.i: 9, n2.i: 47
2: n1.i: 47, n2.i: 47
3: n1.i: 27, n2.i: 27
**/
//------------------------------------------------
//: c03:PassObject.java オブジェクトを渡す
//
class Letter
{
char c;
}
public class PassObject
{
static void f(Letter x)
{
x.c = 'z';
}
public static void main(String[] args)
{
Letter x = new Letter();
x.c = 'a';
System.out.println("1: x.c: " + x.c);
f(x);
System.out.println("2: x.c: " + x.c);
}
}
/**
1: x.c: a
2: x.c: z
**/
//------------------------------------------------
//: c03:Equivalence.java イコールの定義
public class Equivalence
{
public static void main(String[] args)
{
Integer n1 = new Integer(47);
Integer n2 = new Integer(47);
System.out.println(n1 == n2);// 値が格納されているメモリアドレスが等しいか比べる
System.out.println(n1 != n2);
}
}
/**
false
true
**/
//------------------------------------------------
//: c03:EqualsMethod.java イコールの定義
public class EqualsMethod
{
public static void main(String[] args)
{
Integer n1 = new Integer(47);
Integer n2 = new Integer(47);
System.out.println(n1.equals(n2));//値を比べる
}
}
/**
true
**/
//------------------------------------------------
//: c03:EqualsMethod2.java
class Value
{
int i;
}
public class EqualsMethod2
{
public static void main(String[] args)
{
Value v1 = new Value();
Value v2 = new Value();
v1.i = v2.i = 100;
System.out.println( v1.i == v2.i );
System.out.println( v1.equals(v2));
// System.out.println( (v1.i).equals(v2.i) ) ;// Error !
}
}
/**
true
false
**/
//------------------------------------------------
//: c03:ShortCircuit.java 論理演算子 boolean
public class ShortCircuit
{
static boolean test1(int val)
{
System.out.println("test1(" + val + ")");
System.out.println("result: " + (val < 1));
return val < 1;
}
static boolean test2(int val)
{
System.out.println("test2(" + val + ")");
System.out.println("result: " + (val < 2));
return val < 2;
}
static boolean test3(int val)
{
System.out.println("test3(" + val + ")");
System.out.println("result: " + (val < 3));
return val < 3;
}
public static void main(String[] args)
{
if(test1(0) && test2(2) && test3(2))// All true
{
System.out.println("expression is true");
} else {
System.out.println("expression is false");
}
}
}
/**
test1(0)
result: true
test2(2)
result: false
test3(2)
result: true
expression is false
**/
//------------------------------------------------
//: c03:IfElse.java if-else
public class IfElse
{
static int test(int testval, int target)
{
int result = 0;
if(testval > target)
{
result = +1;
}
else if(testval < target)
{
result = -1;
}
else
{
result = 0; // Match
}
return result;
}
public static void main(String[] args)
{
System.out.println(test(10, 5));
System.out.println(test(5, 10));
System.out.println(test(5, 5));
}
}
/**
1
-1
0
**/
//------------------------------------------------
//: c03:WhileTest.java While
public class WhileTest
{
public static void main(String[] args)
{
double r = 0;
while(r < 0.99d)
{
r = Math.random();
System.out.println(r);
}
}
}
/**
0.4643098755141839
0.46956833871910775
0.3023014793430383
0.9343842809456361
0.9642984062528261
0.594761574760128
0.7540668421887108
0.42473394514593177
0.3312915948912968
0.08084027534642113
0.4218415025627196
0.4687745399436214
0.3829927758818946
0.616095194457045
0.011273102047402395
0.4732251094198431
0.33792380108740894
0.5604475435957004
0.5978686611004081
0.35382757166521284
0.5288154146512988
0.3183120940316535
0.99461348729767
**/
//------------------------------------------------
//: c03:ListCharacters.java for loop
public class ListCharacters
{
public static void main(String[] args)
{
for( char c = 0; c < 128; c++)
{
if (c != 26 )// ANSI Clear screen
{
System.out.println("value: " + (int)c + "character: " + c );
}
}
}
}
/**
value: 0character: .....
.
.
.
value: 118character: v
value: 119character: w
value: 120character: x
value: 121character: y
value: 122character: z
value: 123character: {
value: 124character: |
value: 125character: }
value: 126character: ~
value: 127character:
**/
//------------------------------------------------
//: c03:CommaOperator.java for loop
public class CommaOperator
{
public static void main(String[] args)
{
for(int i = 1, j = i + 10; i < 5;i++, j = i * 2)
{
System.out.println("i= " + i + " j= " + j);
}
}
}
/**
Here's the output:
i= 1 j= 11
i= 2 j= 4
i= 3 j= 6
i= 4 j= 8
**/
//------------------------------------------------
//: c03:BreakAndContinue.java break & continue
public class BreakAndContinue
{
public static void main(String[] args)
{
for(int i = 0; i < 100; i++)
{
if(i == 74)
{
break; // Out of for loop
}
if(i % 9 != 0) continue; // Next iteration
{
System.out.println(i);
}
}
int i = 0;
// An "infinite loop":
while(true)
{
i++;
int j = i * 27;
if(j == 1269)
{
break; // Out of loop
}
if(i % 10 != 0)
{
continue; // Top of loop
}
System.out.println(i);
}
}
}
/**
0
9
18
27
36
45
54
63
72
10
20
30
40
**/
//------------------------------------------------
//: c03:VowelsAndConsonants.java switch
public class VowelsAndConsonants
{
public static void main(String[] args)
{
for(int i = 0; i < 20; i++)
{
char c = (char)(Math.random() * 26 + 'a');
System.out.print(c + ": ");
switch(c)
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u': System.out.println("vowel"); break;
default: System.out.println("consonant");
}
}
}
}
/**
c: consonant
r: consonant
d: consonant
c: consonant
j: consonant
j: consonant
k: consonant
v: consonant
w: consonant
s: consonant
a: vowel
r: consonant
v: consonant
i: vowel
q: consonant
y: consonant
t: consonant
l: consonant
x: consonant
s: consonant
**/
///////////////////////////////////////////////////////////////////////////////////////////
//// Chapter 4 コンストラクタと初期化
//------------------------------------------------
//: c04:SimpleConstructor.java デフォルトコンストラクタ
class Rock
{
Rock()// This is the constructor
{
System.out.println("Creating Rock");
}
}
public class SimpleConstructor
{
public static void main(String[] args)
{
for(int i = 0; i < 5; i++)
{
new Rock();
}
}
}
/**
Creating Rock
Creating Rock
Creating Rock
Creating Rock
Creating Rock
**/
//------------------------------------------------
//: c04:SimpleConstructor2.java コンストラクタへ値を渡す
class Rock2
{
Rock2(int i) // This is the constructor
{
System.out.println("Creating Rock number " + i);
}
}
public class SimpleConstructor2
{
public static void main(String[] args)
{
for(int i = 0; i < 5; i++)
{
new Rock2(i);
}
}
}
/**
Creating Rock number 0
Creating Rock number 1
Creating Rock number 2
Creating Rock number 3
Creating Rock number 4
**/
//------------------------------------------------
//: c04:OverloadingOrder.java
// パラメータの内容が異なればコンストラクタの名前は同一でも構わない
public class OverloadingOrder
{
static void print(String s, int i)
{
System.out.println("String: " + s +", int: " + i);
}
static void print(int i, String s)
{
System.out.println("int: " + i + ", String: " + s);
}
public static void main(String[] args)
{
print("String first", 11); // String, int
print(99, "Int first"); // int, String
}
}
/**
String: String first, int: 11
int: 99, String: Int first
**/
//------------------------------------------------
//: c04:DefaultConstructor.java
// デフォルトコンストラクタは省略が可能 自動的に作成される
class Bird
{
}
public class DefaultConstructor
{
public static void main(String[] args)
{
Bird nc = new Bird(); // default!
}
}
/**
**/
//------------------------------------------------
//: c04:Cake.java
class Pie
{
void f()
{
System.out.println("Pie.f()");
}
}
class Cake
{
public static void main(String[] args)
{
Pie x = new Pie();
x.f();
}
}
/**
* Pie.f()
*/
//------------------------------------------------
//: c04:Flower.java
// thisはクラスのコンストラクタを意味する
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 s, int petals)
{
this(petals);
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()
{
System.out.println("petalCount = " + petalCount + " s = "+ s);
}
public static void main(String[] args)
{
Flower x = new Flower();
x.print();
}
}
/**
Constructor w/ int arg only, petalCount= 47
String & int args
default constructor (no args)
petalCount = 47 s = hi
**/
//------------------------------------------------
//: c04:OrderOfInitialization.java
// インスタンスオブジェクトの生成の後、コンストラクタが実行される
class Tag
{
Tag(int marker)
{
System.out.println("Tag(" + marker + ")");
}
}
class Card
{
Tag t1 = new Tag(1); // Before constructor
Card()
{
// Indicate we're in the constructor:
System.out.println("Card()");
t3 = new Tag(33); // Reinitialize t3
}
Tag t2 = new Tag(2); // After constructor
void f()
{
System.out.println("f()");
}
Tag t3 = new Tag(3); // At end
}
public class OrderOfInitialization
{
public static void main(String[] args)
{
Card t = new Card();
t.f(); // Shows that construction is done
}
}
/**
Tag(1)
Tag(2)
Tag(3)
Card()
Tag(33)
f()
**/
//------------------------------------------------
//: c04:ExplicitStatic.java
// static はクラス変数
class Cup
{
Cup(int marker)
{
System.out.println("Cup(" + marker + ")");
}
void f(int marker)
{
System.out.println("f(" + marker + ")");
}
}
class Cups
{
static Cup c1 = new Cup(1);
static Cup c2 = new Cup(2);
Cups()
{
System.out.println("Cups()");
}
}
public class ExplicitStatic
{
public static void main(String[] args)
{
System.out.println("Inside main()");
Cups.c1.f(99);
}
}
/**
Inside main()
Cup(1)
Cup(2)
f(99)
**/
//------------------------------------------------
//: c04:IceCream.java
class Sundae
{
private Sundae()
{
}
static Sundae makeASundae()
{
return new Sundae();
}
}
public class IceCream
{
public static void main(String[] args)
{
//! Sundae x = new Sundae();
Sundae x = Sundae.makeASundae();
}
}
/**
*
*/
//------------------------------------------------
//: c04:Arrays.java
// プリミティブ変数の配列
public class Arrays
{
public static void main(String[] args)
{
int[] a1 = { 1, 2, 3, 4, 5 };
int[] a2;
a2 = a1;
for(int i = 0; i < a2.length; i++)
{
a2[i]++;//increment
}
for(int i = 0; i < a1.length; i++)
{
System.out.println("a1[" + i + "] = " + a1[i]);
}
}
}
/**
a1[0] = 2
a1[1] = 3
a1[2] = 4
a1[3] = 5
a1[4] = 6
**/
]]>
I-ichirow Suzuki _/_/_/_/_/_/_/_/_/_/_
URL : www.kg-group.com Top Page
Mail : suzuki@kg-group.com
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