java新手筆記17 參數

標籤：

package com.yfs.javase;public class ParamDemo {public static void main(String[] args) {int a = 3, b = 5;change(a,b);System.out.println("a = " + a  + "  b = " + b);Point p = new Point();p.x = 10;p.y = 20;change(p);System.out.println("p.x = " + p.x  + "  p.y = " + p.y);}public static void change(Point p) {//引用指向  是對象int c = p.x;p.x = p.y;p.y = c;}public static  void change(int a, int b) {//局部變數  傳入是數值System.out.println("================");System.out.println("||||||  a = " + a  + "  b = " + b +"||||||");int c = a;a = b;b = c;System.out.println("||||||  a = " + a  + "  b = " + b +"||||||");System.out.println("================");}}class Point {int x;int y;}

 1.Person

package com.yfs.javase;public class Person {public Person() {System.out.println("javase.Person  ***");}}

 2. other Person

package com.yfs.javase.other;public class Person {public Person() {System.out.println("other.Person 對象...");}}

 3.Person 測試

package com.yfs.javase.other;import com.yfs.javase.Person;public class PersonTest {/** * @param args */public static void main(String[] args) {Person p1 = new Person();com.yfs.javase.other.Person p2 = new com.yfs.javase.other.Person();}}

 4.default

package com.yfs.javase.other; class DefaultDemo {}  class Other {    }    /*public*/ class Demo {    }

 5.公有類

package com.yfs.javase.other;//一個java檔案只能有一個public 修飾的類 // 類與檔案同名public /*final*/ class PublicClass {private String name;public int age;protected char sex;int score ;static final int id ;//= 520;//只有一份 所有對象共用static {id = 200;}public PublicClass() {//id = 100;}//方法的許可權public final void publicMethod() {//id = 350;}private void privateMethod() {protectedMethod();}protected void protectedMethod() {}    /*default*/ void defaultMethod() {protectedMethod();}}/*default  public*/ class DefaultClass {}

 6.測試

package com.yfs.javase.other;//同一包下public class AccessTest1 {public static void main(String[] args) {PublicClass pc = new PublicClass();pc.publicMethod();//pc.privateMethod();私人方法不能訪問pc.protectedMethod();pc.defaultMethod();    pc.age = 20;    pc.score = 90;}}

 7.包外測試

package com.yfs.javase;import com.yfs.javase.other.PublicClass;//不同包下public class AccessTest2 {public static void main(String[] args) {PublicClass pc = new PublicClass();pc.publicMethod();//pc.privateMethod();私人方法不能訪問//pc.protectedMethod();protected方法不能訪問//pc.defaultMethod();defautl方法不能訪問}}class Child  extends PublicClass {public void test () {//privateMethod();protectedMethod();//子類可以訪問//defaultMethod();//不同包不能訪問}//@Override//public final void publicMethod() {//// TODO Auto-generated method stub////}}

 

java新手筆記17 參數