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 是对象
int c = p.x;
p.x = p.y;
p.y = c;
}
public static void change(int a, int b) {//局部变量 传入是数值
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 对象...");
}
}
3.Person 测试
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.公有类
package com.yfs.javase.other;
//一个java文件只能有一个public 修饰的类
// 类与文件同名
public /*final*/ class PublicClass {
private String name;
public int age;
protected char sex;
int score ;
static final int id ;//= 520;//只有一份 所有对象共享
static {
id = 200;
}
public PublicClass() {
//id = 100;
}
//方法的权限
public final void publicMethod() {
//id = 350;
}
private void privateMethod() {
protectedMethod();
}
protected void protectedMethod() {
}
/*default*/ void defaultMethod() {
protectedMethod();
}
}
/*default public*/ class DefaultClass {
}
6.测试
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();私有方法不能访问
pc.protectedMethod();
pc.defaultMethod();
pc.age = 20;
pc.score = 90;
}
}
7.包外测试
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();私有方法不能访问
//pc.protectedMethod();protected方法不能访问
//pc.defaultMethod();defautl方法不能访问
}
}
class Child extends PublicClass {
public void test () {
//privateMethod();
protectedMethod();//子类可以访问
//defaultMethod();//不同包不能访问
}
// @Override
// public final void publicMethod() {
// // TODO Auto-generated method stub
//
// }
}