如何从文件中的数据创建对象并将其分配给数组？

Question

我需要从文件中获取信息并将它们创建为对象并将它们放入数组中，以便我可以比较对象的区域并在数组中列出哪个对象具有最大的区域及其在数组中的位置。

我很困惑如何从文件中获取信息并将每个信息创建为一个对象（圆形或矩形），然后在创建该对象后将该对象分配到一个数组中。我认为我的其他课程还不错，我只是坚持完成驱动程序。

通常，我会做类似 Circle c1 = new Circle();要创建一个新对象，但是如何从具有预定义信息的文件中执行此操作并将其分配给数组？

数据：

“CIRCLE”, 1, “blue”, true
“RECTANGLE”, 1, 2, “blue”, true
“RECTANGLE”, 10, 2, “red”, true
“CIRCLE”, 2, “green”
“RECTANGLE”
“CIRCLE”

司机：

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;

public class Driver {
public static void main(String[] args) throws FileNotFoundException {
    Scanner input = new Scanner(new File("C:/Users/Charles/Desktop/GeometricObjectsData.txt"));

    ArrayList<GeometricObject> list = new ArrayList<GeometricObject>();

    while (input.hasNext()) {
        String line = input.nextLine();
        System.out.println(line);
    }
  }
}

几何对象：

public abstract class GeometricObject {
    //class variables
    private String color;
    private boolean filled;

    //constructors
    public GeometricObject() {
        super();
        color = "white";
        filled = false;
    }

    public GeometricObject(String color, boolean filled) {
        super();
        this.color = color;
        this.filled = filled;
    }

    //mutators
    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public boolean isFilled() {
        return filled;
    }

    public void setFilled(boolean filled) {
        this.filled = filled;
    }

    //user-defined methods
    public abstract double getArea();

    public abstract double getPerimeter();

    @Override
    public String toString() {
        return super.toString() + " \tColor=" + this.getColor() + " \tFilled=" + this.isFilled();
    }

}

圈子：

 public class Circle extends GeometricObject {
//class variables
private double radius;

//constructors
public Circle() {
    super();
    radius = 1;
}

public Circle(double radius, String color, boolean filled) {
    super(color, filled);
    this.radius = radius;
}

//mutators
public double getRadius() {
    return radius;
}

public void setRadius(double radius) {
    this.radius = radius;
}

//user-defined methods
@Override
public double getArea() {
    //area of a circle
    return (radius * radius * Math.PI);
}

@Override
public double getPerimeter() {
    //perimeter of a circle
    return (2 * radius * Math.PI);
}

@Override
public String toString() {
    return super.toString() + "\nCircle: Radius=" + this.getRadius();
    }

}

矩形：

public class Rectangle extends GeometricObject {
    //class variables
    private double height;
    private double width;

    //constructors
    public Rectangle() {
        super();
        height = 1;
        width = 1;
    }
    public Rectangle(double height, double width, String color, boolean filled) {
        super(color,filled);
        this.height = height;
        this.width = width;
    }

    //mutators
    public double getHeight() {
        return height;
    }
    public void setHeight(double height) {
        this.height = height;
    }
    public double getWidth() {
        return width;
    }
    public void setWidth(double width) {
        this.width = width;
    }

    //user-defined methods
    @Override
    public String toString() {
        return super.toString() + "\nRectangle: Height=" + this.height + "\tWidth=" + this.width;
    }
    @Override
    public double getArea() {
        return (height * width);
    }

    @Override
    public double getPerimeter() {
        return (2 * height + 2 * width);
    }

}

Answer 1

• 在您的文本文件中，您的形状项目周围有特殊的引号。这会让你的生活更加困难，所以如果可能的话，你应该改变它
• 如何制作对象的示例（来自您的 main 方法）：

while (input.hasNext()) { String line = input.nextLine(); System.out.println(line); String[] parts = line.split(","); if (parts[0].indexOf("Circle") != -1) { Circle c = new Circle(); // ... parse the rest of the attributes to set up your circle } else if ... // fill in the other shape cases }