Java测试类获胜'；不编译

我写了四个协作类，其中一个叫做

工作站
：

这是
工作站
类的代码

import java.util.ArrayList;

public class WorkStation {

    /**
     * the pc
     */
    private Hardware pc;

    /**
     * list of available software
     */
    private ArrayList<Software> applications;

    /**
     * whether a web camera is attached or not
     */
    private boolean hasWebCamera;

    /**
     * id number of the Workstation
     */
    private final int idNumber;

    /*
     * Constructor with three parameters
     */
    public WorkStation(Hardware pc, boolean hasWebCamera, int idNumber) {

        this.pc = pc;
        this.hasWebCamera = hasWebCamera;
        this.idNumber = idNumber;
        applications = new ArrayList<Software>();

    }

    //------------------------------- Getter Methods ------------------------------
    /*
     * Gets the pc
     * 
     * @return The pc
     */
    public Hardware getPc() {
        return pc;
    }

    /*
     * Gets whether there is a web camera
     * 
     * @return True or false
     */
    public boolean isHasWebCamera() {
        return hasWebCamera;
    }

    /*
     * Gets the id number
     * 
     * @return The id number
     */
    public double getIdNumber() {
        return idNumber;
    }

    //--------------------------- Setter Methods -------------------------
    /*
     * Sets the pc
     * 
     * @param The pc
     */
    public void setPc(Hardware pc) {
        this.pc = pc;
    }

    /*
     * Sets whether there is a web camera
     * 
     * @param True or false
     */
    public void setHasWebCamera(boolean hasWebCamera) {
        this.hasWebCamera = hasWebCamera;
    }

    // --------------------- ArrayList Methods --------------------
    /*
     * Method to add a piece of software to the list
     */
    public void addSoftware(Software software) {
        applications.add(software);
    }

    /*
     * Method to remove a piece of software from the list
     */
    public void removeSoftware(Software software) {
        applications.remove(software);
    }

    /*
     * Method to remove all software from the list
     */
    public void clearApplications(Software software) {
        applications.clear();
    }

    /*
     * toString Method
     * 
     * @param aPc
     * 
     * @param aHasWebCamera
     * 
     * @param aIdNumber
     */
    public String toString() {
        return "Pc is " + getPc() + ", web camera is " + isHasWebCamera() + 
                " and ID number is " + getIdNumber();
    }

}//end of class

我遇到的问题是，当我试图编译测试类中的内容时，会出现一条错误消息，上面说：

cannot find symbol
symbol  : constructor WorkStation() location: class WorkStation: 
WorkStation w1 = new WorkStation();

我真的不明白为什么会这样。
工作站
类编译得很好，而
测试
类中的其他类编译得很好，所以有人能看到为什么
工作站
类不能在
测试
类中编译吗
 原因是这一行：

WorkStation w1 = new WorkStation();

您的
工作站
类未包含任何无参数构造函数。如果类中已经定义了参数构造函数，Java编译器不会在类中插入默认构造函数。因此，您必须在
工作站
类中定义一个无参数构造函数。
您定义了一个构造函数：

import java.util.ArrayList;

public class WorkStation {

    /**
     * the pc
     */
    private Hardware pc;

    /**
     * list of available software
     */
    private ArrayList<Software> applications;

    /**
     * whether a web camera is attached or not
     */
    private boolean hasWebCamera;

    /**
     * id number of the Workstation
     */
    private final int idNumber;

    /*
     * Constructor with three parameters
     */
    public WorkStation(Hardware pc, boolean hasWebCamera, int idNumber) {

        this.pc = pc;
        this.hasWebCamera = hasWebCamera;
        this.idNumber = idNumber;
        applications = new ArrayList<Software>();

    }

    //------------------------------- Getter Methods ------------------------------
    /*
     * Gets the pc
     * 
     * @return The pc
     */
    public Hardware getPc() {
        return pc;
    }

    /*
     * Gets whether there is a web camera
     * 
     * @return True or false
     */
    public boolean isHasWebCamera() {
        return hasWebCamera;
    }

    /*
     * Gets the id number
     * 
     * @return The id number
     */
    public double getIdNumber() {
        return idNumber;
    }

    //--------------------------- Setter Methods -------------------------
    /*
     * Sets the pc
     * 
     * @param The pc
     */
    public void setPc(Hardware pc) {
        this.pc = pc;
    }

    /*
     * Sets whether there is a web camera
     * 
     * @param True or false
     */
    public void setHasWebCamera(boolean hasWebCamera) {
        this.hasWebCamera = hasWebCamera;
    }

    // --------------------- ArrayList Methods --------------------
    /*
     * Method to add a piece of software to the list
     */
    public void addSoftware(Software software) {
        applications.add(software);
    }

    /*
     * Method to remove a piece of software from the list
     */
    public void removeSoftware(Software software) {
        applications.remove(software);
    }

    /*
     * Method to remove all software from the list
     */
    public void clearApplications(Software software) {
        applications.clear();
    }

    /*
     * toString Method
     * 
     * @param aPc
     * 
     * @param aHasWebCamera
     * 
     * @param aIdNumber
     */
    public String toString() {
        return "Pc is " + getPc() + ", web camera is " + isHasWebCamera() + 
                " and ID number is " + getIdNumber();
    }

}//end of class

public WorkStation(Hardware pc, boolean hasWebCamera, int idNumber){

        this.pc = pc;
        this.hasWebCamera = hasWebCamera;
        this.idNumber = idNumber;
        applications = new ArrayList<Software>();

}

public WorkStation(){...}

您需要定义一个构造函数：

public WorkStation(Hardware pc, boolean hasWebCamera, int idNumber){

        this.pc = pc;
        this.hasWebCamera = hasWebCamera;
        this.idNumber = idNumber;
        applications = new ArrayList<Software>();

}

public WorkStation(){...}

默认构造函数是自动生成的无参数构造函数，除非您定义另一个构造函数。它将所有未初始化的字段初始化为其默认值。由于您定义了一个构造函数，因此没有生成默认构造函数…
您的工作站类只有一个构造函数，它包含3个参数。您正在尝试使用一个不存在的无参数构造函数

如果您没有定义任何构造函数，则会为您添加一个无参数构造函数，但一旦您定义了至少一个构造函数，则不会创建默认的无参数构造函数，如果您需要，则必须定义它。
WorkStation
没有无参数构造函数。添加它或使用它拥有的构造函数。