java1 material

Java 1 : 280: (2010/1/29) ISBN-10: 4798120987ISBN-13: 978-4798120980 2010/1/29 Java1

1 Java

JavaJavaclass FirstExample { public static void main(String[] args) { System.out.println(""); }}

JavaJavaWindowsMac OSLinuxOS

C/C++ 1/2B(#include #define #if #ifdef ) C/C++

C/C++ 2/2Bbooleantrue/falsenew int[] a = new int[5];delete String String str = "Hello"; C/C++

Java Examplepublic static void main(String[] args) { } {}class { public static void main(String[] args) { }}

Java(;)class FirstExample { public static void main(String[] args) { System.out.println(""); }}

{ } 11{ } class FirstExample {public static void main(String[] args) {System.out.println("");}}

1 /* */ 2 // 1/* 2010121*/class FirstExample { public static void main(String[] args) { // System.out.println(""); }}

1

2 Eclipse> javac FirstExample.java > java FirstExample

Eclipse [][][Java] [][][] [][][Java]

Compile Error (0)(o)(O) (1)(I)(l) (;)(:) (.)(,)

.java.class.java FirstExample.java.class FirstExample.classEclipseworkspace

JavaJavaFirstExample.java .java.class

2 Java

EclipseSystem.out.println();class FirstExample { public static void main(String[] args) { System.out.println(""); }}

\System.out.println( "\"Java\"");

System.out.println"Java"

int i; // i = 5; // System.out.println(i); //

; 1 int i; 2 double d; 3 boolean boo = false; 4 char c = '';

doublebooleancharclass Example { public static void main(String args[]) { int i; i = 5; System.out.println(i); } }

System.out.println(2 + 3);

+,-*,/System.out.println(3 + 6 / 3); // 5System.out.println((3 + 6) /3); // 3

class Example { public static void main(String args[]) { System.out.println(2 + 3); }}

int i = 10;int j = i * 2;System.out.println(j); // 20int i = 10;i = i + 3;System.out.println(i); // 13int i = 10;i += 3; // System.out.println(i); // 13

a = a + 5;b = b - 6;c = c * a;d = d / 3;e = e % 2;f = f + 1;g = g - 1;

class CalcExample3 { public static void main(String[] args) { int i; i = 11; i++; i /= 2; System.out.println("i" + i);

int j; j = i * i; System.out.println("j" + j); }}

i = 2 + 3;i = 2 + 3int i;int j = (i = 2 + 3) * 2;System.out.println(i); System.out.println(j); // 5// 10

i++;++i;i1j=i++;j=++i;jj = i; i = i + 1;i = i + 1; j = i;

int i = 10;int j = i++;int k = ++i;System.out.println(i);System.out.println(j);System.out.println(k);

double > int

(double)(int)

double d = 9.8;int i = d; double d = 9.8;int i = (int)d;

doubleint i = 5;double d = 0.5;System.out.println(i + d); // 5.5

5/2 2 double double c = (double)a/(double)b;int a = 5;int b = 2;double c = a / b;System.out.println(c); // 2.0

723.5class Example { public static void main(String[] args) { int a = 7; int b = 2; double d = a / b; System.out.println(d); }}

String StringString s;s = "";System.out.println(s); +String s1 = "";String s2 = "";String s3 = s1 + s2;System.out.println(s3);

if() { ;}if() { ; //true}

if(age < 20) { System.out.println("");}

2 true false

a 20 a 20 a a a 3 a a 5 2

if else if() { ;} else { ;}if() { //true 1; } else { //false 2; }

ifelseint age;age = 20;if(age < 20) { System.out.println("");} else { System.out.println("");}

if else int age;age = 20;if(age < 4) { System.out.println("");} else if(age < 13) { System.out.println("");} else { System.out.println("");}

ifelse

ifelseif( == ) { if( == true) { } else { }} else { }

a 3, 5, 8, 9, 10, 15, 20 if(a < 5) { System.out.println("A");} else if(a < 9) { System.out.println("B");} else if(a < 15) { System.out.println("C");} else { System.out.println("D");}

if{}if(age >= 20) System.out.println("");if(age >= 20) {System.out.println("");}if1{}2{}if(age >= 20) System.out.println("");System.out.println("");

switchbreak;

switchswitch (score) {case 1:System.out.println("");break;case 2:System.out.println("");break;case 3:System.out.println("");break;case 4:System.out.println("");break;case 5:System.out.println("");break;default:System.out.println("");}System.out.println("switch");

switch(2)switch (score) {case 1:case 2:System.out.println("");break;case 3:case 4:case 5:System.out.println("");break;default:System.out.println("");}

switchi1,2,3,4,5switch(i) {case 1: System.out.println("A");case 2: break;case 3: System.out.println("B");case 4:default: System.out.println("C");}

3 ? 1 : 2

true1false2int c;if(a > b) { c = a;} else { c = b;}int c = (a > b) ? a : b;

3

= > 1000 ? : ;

cint a = 5;int b = 3;int c = (a > b) ? a : b;int a = 5;int b = 3;int c = (a > b * 2) ? a + 1 : b - 3;int a = -5;int c = (a > 0) ? a : -a;(a)(b)(c)

age13 age65age >= 13 && age < 65age13 age 65 20age >= 13 && age < 65 && age !=20age13 age 65age < 13 || age >= 65

a + 10 > b * 5(a + 10) > (b * 5)a > 10 && b < 3(a > 10) && (b < 3)x && ( y || z )(x && y ) || z

if( == && != ) { }

a,b,c

abbc abac a,b,cc c>b>a acab ab2ab3

3forwhiledo while

forforfor(; ; ){ }true false for 2.

forfor(int i = 0; i < 5; i++) { System.out.println("");}

forint sum = 0;for(int i = 1; i

110011002312x-10101

{ } class ForExample2 { public static void main(String[] args) { int sum = 0; for(int i = 1; i

whilewhilewhile(){ }true false while1.

for

whileint i = 0;while(i < 5) { System.out.println(""); i++; // }int i = 5;while(i > 0) { System.out.println(i); i--; // }

do whiledo whiledo { } while();true1. false dowhile

forwhile1

do whileint i = 0;do { System.out.println(""); i++;} while(i < 5);int i = 5;do { System.out.println(i); i--; } while(i > 0);

breakbreak; int sum = 0;for(int i = 1; i 20) { System.out.println("20"); break; }}System.out.println("" + sum );

continue continue; int sum = 0;for(int i = 1; i

for(int a = 1; a

1x1=1 2x1=2 3x1=3 4x1=4 5x1=5 6x1=6 7x1=7 8x1=8 9x1=9 1x2=2 2x2=4 3x2=6 4x2=8 5x2=10 6x2=12 7x2=14 8x2=16 9x2=18 1x3=3 2x3=6 3x3=9 4x3=12 5x3=15 6x3=18 7x3=21 8x3=24 9x3=27 1x4=4 2x4=8 3x4=12 4x4=16 5x4=20 6x4=24 7x4=28 8x4=32 9x4=36 1x5=5 2x5=10 3x5=15 4x5=20 5x5=25 6x5=30 7x5=35 8x5=40 9x5=45 1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36 7x6=42 8x6=48 9x6=54 1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49 8x7=56 9x7=63 1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64 9x8=72 1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81class Example { public static void main(String args[]) { for(int i = 1; i

int[] scores; scores = new int[5]; scores[0] = 50; scores[4] = 80; System.out.println(scores[2]);[]0(-1)

int[] scores;scores = new int[5];scores[0] = 50;scores[1] = 55;scores[2] = 70;scores[3] = 65;scores[4] = 80;

for(int i = 0; i < 5; i++) {System.out.println(scores[i]);}

int[] scores = {50, 55, 70, 65, 80};int n = scores.length;

011325364552class Example { public static void main(String args[]) { int counts[] = {1, 3, 5, 6, 5, 2};

}}0:*1:***2:*****3:******4:*****5:**

int[][] scores = new int[3][5];scores[0][0] = 50;scores[2][3] = 65;

classJava class

2(x=2,y=5)(x=-1,y=3)(0,0)1(3,4)5

2(x,y)class Point { int x; int y;}Pointxyintxy2Point

class { }

class { }

newnew Point();Point p = new Point();Point p = new Point();p.x = 10;p.y = 5;

Pointxy Point p = new Point(); p.x = 10; px

Pointclass Point { int x; // x int y; // y}

class PointInstanceExample { public static void main(String[] args) { Point p1 = new Point(); p1.x = 10; p1.y = 5;

Point p2 = new Point(); p2.x = 5; p2.y = 2;

System.out.println("p1x" + p1.x); System.out.println("p1y" + p1.y); System.out.println("p2x" + p2.x); System.out.println("p2y" + p2.y); }}

Javaint, double, boolean

Point p = new Point(); pPoint

class Dog { String name;}

class Example { public static void main(String[] args) { Dog dog1 = new Dog(); dog1.name = "Taro"; Dog dog2 = new Dog(); dog2.name = "Pochi"; Dog dog3 = dog2; System.out.println(dog3.name); dog3.name = "Jiro"; System.out.println(dog2.name); }}

Point p1 = new Point();Point p2 = new Point();Point p3 = p2;p1.x = 0; p1.y = 0; p2.x = 5; p2.y = 10;

Point[] points = new Point[5];points[0] = new Point();points[1] = new Point();points[2] = new Point();points[3] = new Point();points[4] = new Point();

nullnullPoint[] points = new Point[5];points[0] = new Point();points[1] = new Point();points[2] = new Point();

nullnullPoint p;p = null;nullPoint p = new Point();if(p == null) { System.out.println("pnull");} else { System.out.println("pnull");}

Pointx,y Point

class { // // }void () {}

class Point { int x; int y;

// void printPosition() { System.out.println("(" + this.x + ", " + this.y + ")"); }}Point p = new Point();p.x = 10;p.y = 5;p.printPosition();this

void ( ) {}

()class Point { int x; int y; // xyn void multiply(int n) { this.x *= n; this.y *= n; }}Point p = new Point();p.x = 10;p.y = 5;p.multiply(2);Point

class Point { int x; int y; // xydxdy void add(int dx, int dy) { this.x += dx; this.y += dy; }}Point p = new Point();p.x = 10;p.y = 5;p.add(2,3);Point

() { return ;}

return 1class Point { int x; int y; // xy int getXY() { return this.x*this.y; }}Point p = new Point();p.x = 10;p.y = 5;int xy = p.getXY();Point


boolean isSamePosition(Point p) { if(this.x == p.x && this.y == p.y) { return true; } else { return false; } }}Point p1 = new Point();p1.x = 10;p1.y = 5;Point p2 = new Point();p2.x = 10;p2.y = 10;if(p1.isSamePosition(p2)){ System.out.println("");} else { System.out.println("");}

Point

void () {}void ( ) {} ( ) {return ;}

if(this.x == p.x && this.y == p.y) { return true;} else { return false;}return (this.x == p.x && this.y == p.y);if(p1.isSamePosition(p2) == true) { }if(p1.isSamePosition(p2)) { }

() { }


// Point(int x, int y) { this.x = x; this.y = y; }}Point p = new Point(5, 10);System.out.println(p.x);System.out.println(p.y);Point

class Rectangle { double width; // double height; // }

1.RectanglegetArea2.3.RectangletruefalseisLarger


void set(int x, int y) { this.x = x; this.y = y; }

void set(Point p) { this.x = p.x; this.y = p.y; }}

Point p1 = new Point();p1.set(10, 0);

Point p2 = new Point(); p2.set(p1);2


Point() { this.x = 0; this.y = 0; }

Point(Point p) { this.x = p.x; this.y = p.y; }

Point(int x, int y) { this.x = x; this.y = y; }}Point p1 = new Point();Point p2 = new Point(10, 20);Point p3 = new Point(p2);

thisthis.this.()this()

thisthisclass Point { int x; int y;

void set(int x, int y) { this.x = x; this.y = y; }

void set(Point p) { this.x = p.x; this.y = p.y; }}

static Point counterint

class Point { static int counter = 0; int x; int y;}

class Point { static int counter = 0; int x; int y;}

class Point { static int counter = 0; int x; int y;

Point(int x, int y) { this.x = x; this.y = y; Point.counter++; }}System.out.println( Point.counter);

Point p1 = new Point(0, 0);Point p2 = new Point(5, 0);Point p3 = new Point(10, 5);

System.out.println( Point.counter);.1

thisclass Point { static int counter = 0; int x; int y;

Point(int x, int y) { this.x = x; this.y = y; Point.counter++; }}

. static

class SimpleCalc { // static double getTriangleArea(double base, double height) { return base * height / 2.0; }}System.out.println("105" + SimpleCalc.getTriangleArea(10, 5) + "");

class { }

Java[ (1) ][ (1) ][ (1) ][ (2) ][ (3) ]new[ (4) ][ (3) ]intdouble[ (5) ][ (4) ] [ (6) ][ (6) ][ (7) ](a) (b) (c) (d) (e) (f) (g)null (h) (i)

JavaABABBABABAAB

Java1Object

extendsclass A { A}

class B extends A { }ABBABextends A

ObjectObjectextends Object class A extends Object { A}

class B extends A { }


void printInfo() { System.out.println(x); System.out.println(y); }}class ColorPoint extends Point { String color;}ColorPoint cp = new ColorPoint(); cp.x = 5;cp.y = 10;cp.color = "";


void printInfo() { // }}class ColorPoint extends Point { String color;

void printInfo() { // }}ColorPoint cp = new ColorPoint(); cp.printInfo();

(1) ABAB(2) (3) (4)


void printInfo() { // }}class ColorPoint extends Point { String color;

void printInfo() { super.printInfo(); }}super.();

super();

class B extends A {}class B extends A { B() { super(); }}

class B extends A { B() { abc(); } B(int i) { def();}}class B extends A { B() {super();abc();} B(int i) {super(); def();}}

class X { X() { System.out.println("[X]");} void a() { System.out.println("[x.a]");} void b() { System.out.println("[x.b]");}}class Y extends X { Y() { System.out.println("[Y]"); } void a() { System.out.println("[y.a]"); }}X,YX x = new X();x.a();x.b();Y y = new Y();y.a();y.b();

class X { X() { System.out.println("[X()]");} X(int i) { System.out.println("[X(int i)]");}}class Y extends X { Y() { System.out.println("[Y()]"); } Y(int i) { System.out.println("[Y(int i)]"); }}class Z extends Y {}X,YY y0 = new Y();Y y1 = new Y(10);Z z = new Z();

Point p = new Point();ColorPoint cp = new ColorPoint();Point cp = new ColorPoint();PointColorPoint

class Person { void work() { // "" }}

class Student extends Person { void work() { // "" }}

class Teacher extends Person { void work() { // "" } void makeTest() { }}Person[] persons = new Person[3];persons[0] = new Person();persons[1] = new Student();persons[2] = new Teacher();

for(int i = 0; i < 3; i++) {persons[i].work();}

// 3void workThreeTimes(Person p) { p.work(); p.work(); p.work();}Personnew Teacher(), new Student()work

A,B,C class A { } class B extends A { } class C { }(1) A a = new A();(2) A a = new B();(3) A a = new C();(4) B b = new A();(5) B b = new B();(6) B b = new C();

Person p = new Teacher();Teacher t = (Teacher)p;t.makeTest();Person p = new Teacher();((Teacher)p).makeTest();

privateprivate

privateclass Car { private int speed; // (Km/h)

// speed180 public void speedUp() { if(speed < 80) {speed++; } }

// speed10 public void speedDown() { if(speed > 0) { speed--; } }}

class Example { private int valueA; private int valueB;

public int getValueA() { return valueA; } public void setValueA(int a) { valueA = a; } public int getValueB() { return valueB; } public void setValueA(int b) { valueB = b; }}

finalfinal

public final static double PI = 3.141592653589793;public final static int ADULT_AGE = 20;if(age == 20) { }if(age == ADULT_AGE) { }

static static int counter = 0;static double getSum(int x, int y) {return x + y;}public static void main(String args[]) { }

abstractabstract class Shape {}ShapeShape s = new Shape();

abstractabstract class Shape { abstract void draw();}

abstract class Shape { abstract void draw();}

class Polyline extends Shape { void draw() { // }}class Rectangle extends Shape { void draw() { // }}class Circle extends Shape { void draw() { // }}Shape[] shapes = new Shape[3];shapes[0] = new Polyline();shapes[1] = new Rectangle();shapes[2] = new Circle();

for(int i = 0; i < 3; i++) {shapes[i].draw();}

interface { }interface HasGetAreaMethod { double getArea();}class implements { }

interface HasGetAreaMethod { double getArea();}class Rectangle implements HasGetAreaMethod { double getArea() { return width*height;}}class Circle implements HasGetAreaMethod { double getArea() { return r*r*3.14;}}HasGetAreaMethod r = new Rectangle();HasGetAreaMethod c = new Circle();

interface I {}abstract class A {}class B extends A {}class C implements I {} A a = new A(); B b = new B(); C c = new C(); I i = new I();5. A b = new B();6. B a = new A();7. I b = new B();8. I c = new C();

*******************************************************************************************************************************************************************************

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