需要帮助解决 Square 类，特别是代码？

Question

我正在尝试学习 java，但我被困在“类”部分。他们给了我一个问题，我不知道为什么会出错。

我已经阅读了很多，但我不明白为什么会有大约 14 条错误消息？完全...

这是作业：

  // You are to write the constructor specified for this Square class. The Square class 
  // has an instance variable of type double, side, which is the length of each side of 
  // the square. The javadoc has been provided for you to help you tell what you needs to
  // be done
 // 
 // HINT: Write the constructor for the class Square.
 // The constructor will take in a parameter of the type double
 // and assign that parameter to the instance variable side

这是我的代码：

   public class Square(double side)

  private double side;

  /**
  * Constructor for objects of class Square
  * @param theSide the length of the side of this Square
  */
  public main(double theSide) {
  side = theSide;
  }
  /**
  * Gets the length of a side of this square
  * @return the side of this square
  */
  public double getSide()
  {
   return side;
  }


Compiler error: /tmp/codecheck.XNhW00Z3c8/Square.java:12: error: '{'    expected public class Square(double side) ^ /tmp/codecheck.XNhW00Z3c8/Square.java:12: error: ';' expected public class Square(double side) ^ /tmp/codecheck.XNhW00Z3c8/Square.java:31: error: reached end of file while parsing } ^ /tmp/codecheck.XNhW00Z3c8/Square.java:14: error: variable side is already defined in class Square private double side; ^

Answer 1

您实际上是在为类提供参数。在java类中不应该有参数

看这里

public class Square(double side)

正道课

public class Square
{
    private double side;
    public Square(double theSide)
    {
        side=theSide;
    }
    public double getSide()
    {
        return side;
    }


}

另一个类

public class TestSquare
{

    public static void main(String[] args)
    {
        Square square = new Square(25.00);
        System.out.println("Square sides:"+square.getSide());
    }
}