java 的訪問權限控制

 

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 方法能夠在類外部訪問 p.age=12;//這個方法是錯誤的，私有方法，只能在類內部訪問 } //public 能夠直接訪問這個類內部的元素 public void setName(){ new PermissionModel().name="li"; } }

訪問權限的控制增強了具體實現的隱藏

定製本身的工具庫取代輸出

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!"); } }