java - 如何从静态上下文引用非静态方法

Question

我有一个带有函数的构造函数，但是当我编译我的主方法时，我无法从静态上下文引用非静态方法区域。我知道这是一个简单的修复，但我只是无法完全到达那里。谢谢

public class Rect{
     private double x, y, width, height;

     public Rect (double x1, double newY, double newWIDTH, double newHEIGHT){
       x = x1;
       y = newY;
       width = newWIDTH;
       height = newHEIGHT;

    }
    public double area(){
       return (double) (height * width);
}

以及这个主要方法

public class TestRect{

    public static void main(String[] args){
        double x = Double.parseDouble(args[0]);
        double y = Double.parseDouble(args[1]);
        double height = Double.parseDouble(args[2]);
        double width = Double.parseDouble(args[3]);
        Rect rect = new Rect (x, y, height, width);
        double area = Rect.area();     

    }    
}

Answer 1

您需要在类的实例上调用该方法。

这段代码:

Rect rect = new Rect (x, y, height, width);
double area = Rect.area();

应该是:

Rect rect = new Rect (x, y, height, width);
double area = rect.area();
              ^ check here
                you use rect variable, not Rect class
                Java is Case Sensitive