如何使用视图计算面积、周长和半径

Question

因此，我正在创建一个应用程序，其主要目的是计算三角形的面积、周长和半径。用户应该输入三个类型为double的值&无论他们点击哪个按钮，都应该在结果视图中显示出答案。用户可以点击任何按钮（不管是哪个按钮）。如果他们先点击"区域"按钮&然后决定点击"周长"按钮，结果应该会改变。下面是一张图片，让您了解它的外观：(http://tinypic.com/r/v3ncyh/8)。我不确定我是否正确编程，因为我的值看起来完全不正确&我认为我的视图没有正确连接到我的代码。这段代码的第一部分是我的Triangle类，它包含了我所有的getter/setters&我计算面积、周长和半径的方法。第二部分是我的活动，它是我的应用程序的主要（也是唯一）活动。

公共类三角形｛

// instance variables
private double sideA;
private double sideB;
private double sideC;
// Getters and setters
public double getSideA() {
    return sideA;
}
public void setSideA(double sideA) {
    this.sideA = sideA;
}
public double getSide2B() {
    return sideB;
}
public void setSideB(double sideB) {
    this.sideB = sideB;
}
public double getSideC() {
    return sideC;
}
public void setSideC(double sideC) {
    this.sideC = sideC;
}
// Constructor
public Triangle(double sideA, double sideB, double sideC) {
    this.sideA = sideA;
    this.sideB = sideB;
    this.sideC = sideC;
}
// Three methods...
public double getPerimeter() {
    return sideA + sideB + sideC;
}
public double getArea() {
    double s = 1/2 * (sideA + sideB + sideC);
    double area = Math.sqrt(s*(s-sideA)*(s-sideB)*(s-sideC));
    return area;
}
public double getInRadius() {
    double r = ((-sideA + sideB + sideC)*(sideA - sideB + sideC)*(sideA + sideB - sideC))/(4*(sideA + sideB + sideC));
    double answer = Math.sqrt(r);
    return r;
}

}

公共类TriangleComputationActivity扩展了Activity｛

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_triangle_computation);
    // Declare our View variables and assign them the Views from the layout file
    final TextView lengthOne = (TextView) findViewById(R.id.lengthOne);
    final TextView lengthTwo = (TextView) findViewById(R.id.lengthTwo);
    final TextView lengthThree = (TextView) findViewById(R.id.lengthThree);
    final TextView result = (TextView) findViewById(R.id.result);
    Button areaButton = (Button) findViewById(R.id.area);
    Button perimeterButton = (Button) findViewById(R.id.perimeter);
    Button inradiusButton = (Button) findViewById(R.id.inradius);
    final Triangle triangle = new Triangle((double)lengthOne.getInputType(), (double)lengthTwo.getInputType(),(double)lengthThree.getInputType());
    // Methods in Action...
    areaButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            result.setText(triangle.getArea());
        }
    });
    perimeterButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            result.setText(triangle.getPerimeter());
        }
    });
    inradiusButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            result.setText(triangle.getInRadius());
        }
    });
}

Answer 1

TextView.getInputType()不会返回对您有用的值。它与TextView的实际文本无关。

您应该使用TextView.getText()。您必须使用Double.parseInt()或Double.valueOf()将其转换为双精度。如果是我，我会在这些TextViews上设置android:inputType="numberDecimal"。