Question

我正在尝试编写一个使用Factory模式计算出形状区域的程序。

我尝试使用调试器，但是我真的是编程新手，所以不要一头雾水。我没有错误消息或红线。 MainActivity：

package com.example.shape;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    ShapeFactory myShapeFactory;
    Shape myShape;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myShapeFactory = new ShapeFactory();
    }


    public void convert(View view) {
        //This tell it to collect the height variable from user input
        EditText heightEditText = findViewById(R.id.heightEditText);
        String getHeight = heightEditText.getText().toString();
        myShape.setHeight(Double.parseDouble(getHeight));


        //This tell it to collect the height variable from user input pass as String, then accept into shape as double for width variable
        EditText widthEditText =  findViewById(R.id.widthEditText);
        String getWidth = widthEditText.getText().toString();
        myShape.setWidth(Double.parseDouble(getWidth));

        //This tell is to allow the user to choose if the area is for a triangle or square
        EditText shapeTypeEditText = findViewById(R.id.shapeTypeEditText);
        String ShapeType = shapeTypeEditText.getText().toString();


        //This states if T is entered to display the area of a Triangle
        myShape = myShapeFactory.getShape("T");
        Toast.makeText(this, Double.toString(myShape.Area()), Toast.LENGTH_LONG).show();

        //This states if S is entered to display the area of a Square
        myShape = myShapeFactory.getShape("S");
        Toast.makeText(this, Double.toString(myShape.Area()), Toast.LENGTH_LONG).show();
    }
}

类形状：

  package com.example.shape;

public abstract class Shape {
    //set variable types to double
    private double width;
    private double height;


        //tells it to get the variable width from input
        public double getWidth () {
        return width;
        }
        //tells it to set the variable width from input
        public void setWidth ( double _width) {
            width = _width;
        }

        public double getHeight () {
        return height;
        }

        public void setHeight(double _height){
            height = _height;
        }

        public abstract double Area();
    }

package com.example.shape;

public class ShapeFactory {
        public Shape getShape(String ShapeType) {
            if (ShapeType==null) {
                return null;
            }
            if (ShapeType=="T") {
                return new Triangle();
            }
            if (ShapeType=="S") {
                return new Square();
            }
            return null;

        }
}


----------
    package com.example.shape;

    public class Square extends Shape {
        @Override
        public double getArea() {
            return super.getHeight() * super.getWidth();
        }

            public double getTinsOfPaint() {
                return super.getHeight()*super.getWidth()/24;
        }
    }


    ----------
    package com.example.shape;

    public class Triangle extends Shape {
        @Override
        public double getArea() {
            return super.getHeight()*super.getWidth()/2;
        }


        public double getTinsOfPaint() {
            return super.getHeight()*super.getWidth()/2/24;
        }

    }

用户应该能够输入宽度和高度，并将其传递给超类Shape，该类具有三角形和正方形的子类，它们可以计算出面积并将其显示在烤面包中。

Answer 1

您遇到的问题是，用一个没有设置值的新Shape对象覆盖已经用值设置的myShape对象。

有几种方法可以解决此问题。以下是一些示例：

您可以设置宽度，高度和其他值，以便可以正确计算面积：

class AuthCallToActionScreen extends Component {
  static navigationOptions = {
    header: null,
  }

  render() {
    return <View><Text>Auth Call To Action - No Header required</Text></View>
  }
}

export default withNavigation(AuthCallToActionScreen)

您可以修改工厂以接受父形状，以便它可以继承所有值（宽度，高度等）。

  myShape = myShapeFactory.getShape("T");
  myShape.setWidth(Double.parseDouble(getWidth)); // You need to setup the width, etc.
  Toast.makeText(this, Double.toString(myShape.Area()), Toast.LENGTH_LONG).show();

为此，我建议您阅读有关Clonable接口和clone方法的信息。另外，您可以检查序列化和复制构造函数。

您可以在Shape中添加一个方法，以便它可以继承另一个图形的值：

  myShape = myShapeFactory.getShape("T", myShape);
  Toast.makeText(this, Double.toString(myShape.Area()), Toast.LENGTH_LONG).show();

此InheritedProperties方法只会将myShape的属性复制到myNewShape中。

让我知道这是否对您有意义。

如何从editText工厂模式获取变量

1 个答案: