No enclosing instance of type EmployeeTest is accessible. Must qualify the allocation with an enclos

相信有很多人开始学习Java的时候都和我一样，用的都是《Java核心技术 卷1》，然后对着书敲代码过来的，今天对着书敲就碰到了一个问题，明明和书上一模一样居然也会出错，非常纳闷。下面粘贴我的代码：

package j208180722;

import java.util.Date;
import java.util.GregorianCalendar;

public class EmployeeTest {
	public static void main(String[] args) {
	
		Employee[] staff=new Employee[3];
		staff[0]=new Employee("Carl Cracker",75000,1987,12,15);
		staff[1]=new Employee("Harry Hacker",50000,1989,10,1);
		staff[2]=new Employee("Tony Testr",40000,1990,3,15);
		
		for(Employee e:staff){
			e.raiseSalary(5);
		}
		
		for(Employee e:staff){
			System.out.println("name="+e.getName()+",salary="+e.getSalary()+",hireDay="+e.getHireDay());
		}
		
	}
	
	class Employee{
		private String name;
		private double salary;
		private Date hireDay;
		
		public Employee(String n,double s,int year,int month,int day){
			name=n;
			salary=s;
			GregorianCalendar calendar=new GregorianCalendar(year,month-1,day);
			hireDay=calendar.getTime();
		}
		
		public String getName(){
			return name;
		}
		
		public double getSalary(){
			return salary;
		}
		
		public Date getHireDay(){
			return hireDay;
		}
		
		public void raiseSalary(double byPercent){
			double raise=salary*byPercent/100;
			salary+=raise;
		}
	}
}

这时编译器报错：

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    No enclosing instance of type EmployeeTest is accessible. Must qualify the allocation with an enclosing instance of type EmployeeTest (e.g. x.new A() where x is an instance of EmployeeTest).

    at j208180722.EmployeeTest.main(EmployeeTest.java:10)

 

在网上查询资料以后才知道，在Java里，静态方法不能直接调用动态方法，主程序开头是public static void main,为静态方法，这时候最好的解决方法就是把class 改成static class,将内部类修饰为静态类。最后贴上改正后的代码：

package j208180722;

import java.util.Date;
import java.util.GregorianCalendar;

public class EmployeeTest {
	public static void main(String[] args) {
	
		Employee[] staff=new Employee[3];
		staff[0]=new Employee("Carl Cracker",75000,1987,12,15);
		staff[1]=new Employee("Harry Hacker",50000,1989,10,1);
		staff[2]=new Employee("Tony Testr",40000,1990,3,15);
		
		for(Employee e:staff){
			e.raiseSalary(5);
		}
		
		for(Employee e:staff){
			System.out.println("name="+e.getName()+",salary="+e.getSalary()+",hireDay="+e.getHireDay());
		}
		
	}
	//在Java中，类中的静态方法不能直接调用动态方法，主程序为public static class开头，所以不能直接调用Employee方法
	static class Employee{
		private String name;
		private double salary;
		private Date hireDay;
		
		public Employee(String n,double s,int year,int month,int day){
			name=n;
			salary=s;
			GregorianCalendar calendar=new GregorianCalendar(year,month-1,day);
			hireDay=calendar.getTime();
		}
		
		public String getName(){
			return name;
		}
		
		public double getSalary(){
			return salary;
		}
		
		public Date getHireDay(){
			return hireDay;
		}
		
		public void raiseSalary(double byPercent){
			double raise=salary*byPercent/100;
			salary+=raise;
		}
	}
}