java 的访问权限控制

package test06;

public class PermissionModel {
	private int age;
	public String name;

	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}

}

package test06;

public class PermissionTest {
	public static void main(String[] args) {
		PermissionModel p=new PermissionModel();
		p.getAge();
		p.setAge(12);
		p.getName();
		p.setName("wang");
		p.name="wangsong";//public 方法可以在类外部访问
		p.age=12;//这个方法是错误的，私有方法，只能在类内部访问
	}
	//public 可以直接访问这个类内部的元素
	public void setName(){
		new PermissionModel().name="li";
	}

}

访问权限的控制加强了具体实现的隐藏

定制自己的工具库取代输出

package test06.util;
import java.util.Locale;

public class Print {
	public static void print(boolean b){
		System.out.print(b);
	  }
	  public static void print(char c){
		System.out.print(c);
	  }
	  public static void print(char []s){
		System.out.print(s);
	  }
	  public static void print(double d){
		System.out.print(d);
	  }
	  public static void print(float f){
		System.out.print(f);
	  }
	  public static void print(int i){
		System.out.print(i);
	  }
	  public static void print(long l){
		System.out.print(l);
	  }
	  public static void print(String s){
		System.out.print(s);
	  }
	  public static void printf(Locale l,String format,Object args){
		System.out.printf(l, format, args);
	  }
	  public static void println(){
		System.out.println();
	  }
	  public static void println(boolean b){
		System.out.println(b);
	  }
	  public static void println(char c){
		System.out.println(c);
	  }
	  public static void println(char []s){
		System.out.println(s);
	  }
	  public static void println(double d){
		System.out.println(d);
	  }
	  public static void println(float f){
		System.out.println(f);
	  }
	  public static void println(int i){
		System.out.println(i);
	  }
	  public static void println(long l){
		System.out.println(l);
	  }
	  public static void println(Object obj){
		System.out.println(obj);
	  }
	  public static void println(String s){
		System.out.println(s);
	  }

	}

用static引入包

package test06;
import static test06.util.Print.*;
public class Hello {
	public static void main(String[] args) {
		print("Hello World!");
	}

}