无法在Java中静态导入类

Question

我有一个java文件，其中包含我正在静态导入到另一个文件中的内容列表。

但是，我遇到了编译器“无法找到符号”的错误。

视觉代码也突出了代码的错误：

Syntax error, static imports are only available if source level is 1.5 or greater.

我跟着从这个post的语法。

Constants.java

public final class Constants{ 
    private Constants(){} //Private constructor - no instantiation or subclassing. 

    // The first two members are constants, used to configure the simulator. 
    public static final int MAX_NUMBER_OF_EVENTS = 100; // Maximum number of events 
    public static final double SERVICE_TIME = 1.0; // Time spent serving a customer 
    public static final int CUSTOMER_ARRIVE = 1; 
    public static final int CUSTOMER_DONE = 2; 
} 

Simulator.java

import static Constants.*; //doesn't work. 

public class Simulator{ 
    private Event[] events = new Event[MAX_NUMBER_OF_EVENTS]; //Array to queue events - order of events not guaranteed. 

    //numOfEvents keeps track of number of events in the array. 
    //total* variables used to track simulation. 
    //*Id variables used to identify customer. 
    private int numOfEvents, totalNumOfServedCustomer, totalNumOfLostCustomer = 0; 
    private int lastCustomerId = 0; 
    private int servedCustomerId, waitingCustomerId = -1; 

    //booleans used to track customer status i.e. served or waiting. 
    private boolean customerBeingServed, customerWaiting = false; 

    //doubles used to keep track of time of total simulation and waiting time. 
    private double timeStartedWaiting, totalWaitingTime = 0; 
... 
} 

我在JDK 9运行与Java的Red Hat的语言支持可视化代码

Answer 1

您不能导入来自默认包。

给你的常量类包声明：

package something; 

使用

import static something.Constants.*;