Question

public class Triangle 
{

    float length;  //declared length as float
    float breadth;  //declared breadth as float
    public static void main(String[] args)
    {
        Triangle Triangle1 = new Triangle();
        Triangle Triangle2 = new Triangle();

        float area; //declared area as float

        Triangle1.length = 11;
        Triangle1.breadth = 22;
        Triangle2.breadth = 15;
        Triangle2.length = 20;

        area = 0.5 * Triangle1.length * Triangle1.breadth;
        System.out.println("The area of Triangle is" + " " + area);

        area = 0.5 * Triangle2.length * Triangle2.breadth;
        System.out.println("The area of Triangle is" + " " + area);

    }
}

我之前宣布该区域为浮动，并且我得到了complie时间错误，当我将其更改为double时，我可以得到以下输出。需要知道为什么...... ??

浮动区域;

Error:(24, 49) java: incompatible types: possible lossy conversion from double to float
Error:(27, 49) java: incompatible types: possible lossy conversion from double to float

Answer 1

在Java中，默认情况下，如2.553的数字是 double ，所以当你这样做时

area = 0.5 * Triangle1.length * Triangle1.breadth;

你正在做 double * float * float 。如果您想使用0.5作为浮点数，则需要在数字后面添加字母 f ，这样您的代码将如下所示：

area = 0.5f * Triangle1.length * Triangle1.breadth;

Answer 2

您的代码有几个错误。

请保留命名约定。类以大写字母开头，变量不大写。所以.. Triangle triangle1 = new Triangle()。
为了保留float中的所有数据，您还需要将float中的所有数字相乘。默认情况下，0,5是double，具有比float更大的小数精度。有两种方法可以解决这个问题：

使用F或f指示符（我建议大写的指示符）表示您使用float。否则Java会将其作为double：

area = 0.5F * triangle1.length * triangle1.breadth;

或将所有结果转换为float：

area = (float) 0.5 * triangle1.length * triangle1.breadth;

Answer 3

您有两种选择：

每次初始化浮点变量后添加f，例如Triangle1.length = 11f;

因此代码变为：

public class Triangle {

float length; // declared length as float
float breadth; // declared breadth as float

public static void main(String[] args) {

    Triangle Triangle1 = new Triangle();
    Triangle Triangle2 = new Triangle();

    float area; // declared area as float

    Triangle1.length = 11f;
    Triangle1.breadth = 22f;
    Triangle2.breadth = 15f;
    Triangle2.length = 20f;

    area = 0.5f * Triangle1.length * Triangle1.breadth;
    System.out.println("The area of Triangle is" + " " + area);

    area = 0.5f * Triangle2.length * Triangle2.breadth;
    System.out.println("The area of Triangle is" + " " + area);

}

}

设置area变量double类型：

您的代码因此变为：

public class Triangle {

float length; // declared length as float
float breadth; // declared breadth as float

public static void main(String[] args) {

    Triangle Triangle1 = new Triangle();
    Triangle Triangle2 = new Triangle();

    double area; // declared area as float

    Triangle1.length = 11;
    Triangle1.breadth = 22;
    Triangle2.breadth = 15;
    Triangle2.length = 20;

    area = 0.5 * Triangle1.length * Triangle1.breadth;
    System.out.println("The area of Triangle is" + " " + area);

    area = 0.5 * Triangle2.length * Triangle2.breadth;
    System.out.println("The area of Triangle is" + " " + area);

}

}

希望它有所帮助！

Answer 4

这样做。

    public class Triangle 
{
    float length;  //declared length as float
    float breadth;  //declared breadth as float

    public static void main(String[] args)
    {

        Triangle Triangle1 = new Triangle();
        Triangle Triangle2 = new Triangle();

        float area; //declared area as float

        Triangle1.length = 11;
        Triangle1.breadth = 22;
        Triangle2.breadth = 15;
        Triangle2.length = 20;

        area = (float)0.5 * Triangle1.length * Triangle1.breadth;
        System.out.println("The area of Triangle is" + " " + area);

        area = (float)0.5 * Triangle2.length * Triangle2.breadth;
        System.out.println("The area of Triangle is" + " " + area);
    }
}

为什么我没有获得输出以下代码需要解释？

4 个答案: