class Sum{ static int total; Sum() { total = 0; } void add(int x) { total += x; } } public class Repo6test02 { public static void main(String[] args) { Sum obj1 = new Sum(); Sum obj2 = new Sum(); obj1.add(10); obj1.add(20); obj2.add(30); obj2.add(40); System.out.println("obj1.total = " + obj1.total); System.out.println("obj2.total = " + obj2.total); } } |
obj1.total = 100 obj2.total = 100 |
class Sum { int total; Sum() { total = 0; } Sum(int x){ total = x; } void add(int x){ total += x; } void sub(int y){ total -= y; } } public class Repo6test03 { public static void main(String[] args) { Sum obj1 = new Sum(); obj1.add(10); obj1.sub(20); System.out.println("sum1 = " + obj1.total); Sum obj2 = new Sum(100); obj2.sub(10); obj2.sub(20); System.out.println("sum2 = " + obj2.total); } } |
sum1 = -10 sum2 = 70 |
class Disp { static { System.out.println("initialize Disp"); } Disp() { System.out.println("construct Disp"); } static void Print() { System.out.println("Print Disp"); } } class Body { static { System.out.println("initialize Body"); } Body() { System.out.println("construct Body"); } } public class Repo6test04 { public static void main(String[] args) { Disp obj1 = new Disp(); Disp obj2 = new Disp(); Body obj3 = new Body(); Body obj4 = new Body(); Disp.Print(); } } |
initialize Disp construct Disp construct Disp initialize Body construct Body construct Body Print Disp |
class Display { void Disp() { System.out.println("Nothing"); } void Disp(int x) { System.out.println(x); } void Disp (int x, int y) { System.out.println(x + y); } void Disp (int x, int y, int z) { System.out.println(x + y + z); } void Disp (double x) { System.out.println(x); } } public class Repo6test05 { public static void main(String[] args) { Display obj = new Display(); obj.Disp(); obj.Disp(1); obj.Disp(1,2); obj.Disp(1,2,3); obj.Disp(5.2); } } |
Nothing 1 3 6 5.2 |
class A { static void a() { System.out.println("a"); } static public void b() { System.out.println("b"); } static private void c() { System.out.println("c"); } static protected void d() { System.out.println("d"); } } public class Repo6test062 { public static void main(String[] args) { A obj = new A(); A.a(); A.b(); //A.c(); A.d(); } } |
a b d |
キーワード | 説明 |
public | すべてのクラスにアクセスを許可する |
protected | 同じパッケージ内のコード、または別のパッケージ内のサブクラスに のみアクセスを許可する |
private | 同じクラス内のコードにのみアクセスを許可する |
class Disply { int x =10; void Disp() { System.out.println("Hello!"); } } 1:public class Repo6test07 extends Disply { public static void main(String[] args) { 2: Repo6test07 obj = new Repo6test07(); obj.Disp(); int hensu = obj.x; System.out.println(hensu); } } |
Hello! 10 |
class Disply { void Disp() { System.out.println("スーパークラス"); } } public class Repo6test09 extends Disply { void Disp() { super.Disp(); System.out.println("サブクラス"); } public static void main(String[] args) { Repo6test09 obj = new Repo6test09(); obj.Disp(); } } |
スーパークラス サブクラス |
class Keisan { int x = 100; void add(int x, int y) { int w1 = x + y; int w2 = this.x + y; System.out.println("w1 = " + w1); System.out.println("w2 = " + w2); } } public class Repo6test10 { public static void main(String[] args) { Keisan obj = new Keisan(); obj.add(10,20); } } |
w1 = 30 w2 = 120 |
class Keisan { void Keisan(int x, int y) { System.out.println("Kakezan = " + (x * y)); } void Keisan(int x) { this.Keisan(x,1); } } public class Repo6test11{ public static void main(String[] args) { Keisan obj1 = new Keisan(); obj1.Keisan(200,5); Keisan obj2 = new Keisan(); obj2.Keisan(200); } } |
Kakezan = 1000 Kakezan = 200 |
abstract class Predifine { abstract int add(int x,int y); int sub(int x, int y) { return x - y; } } class Repo6test12 extends Predifine { public int add(int x, int y) { return x+y; } public static void main(String[] args) { Repo6test12 obj = new Repo6test12(); System.out.println("add = " + obj.add(100,80)); System.out.println("sub = " + obj.sub(100,80)); } } |
add = 180 sub = 20 |
interface PreDefine { int add (int x, int y); int sub (int x, int y); } class Repo6test13 implements PreDefine { public int add(int x, int y) { return x + y; } public int sub(int x, int y) { return x - y; } public static void main(String[] args) { Repo6test13 obj = new Repo6test13(); System.out.println("add = " + obj.add(100,80)); System.out.println("sub = " + obj.sub(100,80)); } } |
add = 180 sub = 20 |