创建一个布尔值以找到不同类型的旅行杯

Question

提示：很多TravelCups没有把手。为此，向 TravelCup class 添加一个布尔实例变量。更改您的构造函数和方法以适应此更改。将任何适当的方法添加到此更改所需的 class。证明更改在您的测试运行中有效。

我能够完成大部分项目，但我被困在这里。我不确定我是应该创建一个新的 class 还是创建一个新对象，但我已经尝试创建一个新的构造函数，但它只是给了我一个错误。我已经走到了死胡同，现在我不知道该怎么办。有人可以帮忙吗？

代码：

    public class Cup
{
    // instance variables 
    private int volume; // in oz.
    private String color;
    private String material;

    /**
     * Default Constructor for objects of class Cup
     */
    public Cup()
    {
        // initialise instance variables
        volume = 8;
        color = "white";
        material = "ceramic";
    }
    
    public Cup(int v, String c, String m)
    {
        // initialise instance variables
        volume = v;
        color = c;
        material = m;
    }
    
    public Cup(Cup other)
    {
        // initialise instance variables
        volume = other.volume;
        color = other.color;
        material = other.material;
    }
    
    public void set(int v, String c, String m)
    {
        volume = v;
        color = c;
        material = m;
    }
    
    public String toString()
    {
        return "This is a " + color + " cup made of " + material
                + "\nIt holds " + volume + " oz. ";
    }

    /**
     *
     * @return    the volume
     */
    public int getVolume()
    {
        return volume;
    }
    
    public String getColor()
    {
        return color;
    }
    
    public String getMaterial()
    {
        return material;
    }
    
    public boolean equals(Cup other)
    {
        if(other == null)
            return false;
        else if( getClass() != other.getClass())
            return false;
        else
        {
            Cup otherCup = (Cup)other;
            return volume == otherCup.volume && color.equals(otherCup.color) && material.equals(otherCup.material);
        }
    }
}


public class LogoCup extends Cup
{
    private String logo;
    private String slogan;

    public LogoCup()
    {
        super( );
        logo = "";
        slogan = "";
    }
    
    public LogoCup(int v, String c, String m, String lg, String s)
    {
        super(v, c, m );
        logo = lg;
        slogan = s;
    }
    
        public LogoCup(LogoCup other)
    {
        super(other );
        logo = other.logo;
        slogan = other.slogan;
    }

        public String toString()
    {
        return super.toString()
                + " Logo: " + logo + " Slogan: " + slogan;
    }
    
    public boolean equals(LogoCup other)
   {
       if(other == null)
        return false;
       else if( getClass() != other.getClass())
        return false;
       else
       {
           LogoCup otherLogoCup = (LogoCup)other;
           return logo.equals(otherLogoCup.logo) && slogan.equals(otherLogoCup.slogan) && super.equals( otherLogoCup);
       }
    } 
    
    
    public String getLogo()
    {
        
        return logo;
    }
    
        public String getSlogan()
    {
        return slogan;
    }
}



public class TravelCup extends LogoCup
{
    public TravelCup()
    {
        super();
    }
  
    
    public TravelCup(int v, String c, String m, String lg, String s)
    {
        super(v, c, m, lg, s );

    }
    
        public TravelCup(TravelCup other)
    {
        super(other );
    }

 
    public String toString()
    {
        return "Travel Cup! " + super.toString() + "\nEvery TravelCup has a lid!";
    }
    
    public boolean equals(Object other)
    {
       if(other == null)
            return false;
       else if( getClass() != other.getClass())
            return false;
       else
        {
            TravelCup otherTravelCup = (TravelCup)other;
            return super.equals( otherTravelCup);
        }
    } 
    
    public boolean equals(Object handle);
    {
    
    }
    
}

Answer 1

TravelCup 可以通过以下更新实现：

添加字段 boolean hasHandle，其 getter 并通过构造函数设置
更新构造函数以使用现有的构造函数 this(...)
更新了 toString 和 equals 以包含新字段
（可选）添加了 set 方法以通过调用 super.set 来设置所有需要添加到 LogoCup

class TravelCup extends LogoCup {
    private boolean hasHandle = false;
    
    public TravelCup() {
        super();
    }
  
    public TravelCup(int v, String c, String m, String lg, String s) {
        this(v, c, m, lg, s, false);
    }
    
    public TravelCup(int v, String c, String m, String lg, String s, boolean h) {
        super(v, c, m, lg, s );
        this.hasHandle = h;
    }

    public TravelCup(TravelCup other) {
        super(other);
        this.hasHandle = other.hasHandle;
    }
 
    public String toString() {
        return "Travel Cup! " + super.toString() + ", hasHandle? " + hasHandle + "\nEvery TravelCup has a lid!";
    }
    
    public boolean equals(Object other)
    {
        if(other == null)
            return false;
        if (this == other)
            return true;
        if(getClass() != other.getClass())
            return false;
        TravelCup otherTravelCup = (TravelCup) other;
        return super.equals(otherTravelCup) && this.hasHandle == otherTravelCup.hasHandle;
    } 
    
    public boolean hasHandle() {
        return hasHandle; 
    }
    
    public void set(int v, String c, String m, String l, String s, boolean h)
    {
        super.set(v, c, m, l, s);
        this.hasHandle = h;
    }
}

// class LogoCup
class LogoCup extends Cup {
// ...
    public void set(int v, String c, String m, String l, String s) {
        super.set(v, c, m);
        logo = l;
        slogan = s;
    }
}

创建一个布尔值以找到不同类型的旅行杯

Creating a boolean to find a different kind of travel cup

java

boolean