已知三角形边长，求三角形面积

女爷i 2023-10-05 10:12 67阅读 0赞

利用海伦公式求面积：  
![在这里插入图片描述][20200919225135302.png_pic_center]

1.编写三角形类

package com.sanj.bean;
    
    import com.sanj.exception.NotSanjiaoException;
    
    import java.math.BigDecimal;
    
    public class Sanj {
        
    
         private int x;
    	    private int y;
    	    private int z;
    
    	    public Sanj() {
        
    	    }
    
    	    public Sanj(int x, int y, int z) {
        
    	        this.x = x;
    	        this.y = y;
    	        this.z = z;
    	    }
    
    	    /**
    	     * 获取三角形面积
    	     * @return
    	     */
    	    public double getArea(){
        
    	        //利用海伦公式求三角形面积
    	        BigDecimal bigDecimal1 = new BigDecimal((this.x+this.y+this.z));
    	        BigDecimal bigDecimal2 = new BigDecimal(2);
    	        double p = bigDecimal1.divide(bigDecimal2, BigDecimal.ROUND_HALF_UP).doubleValue();
    	        double area = Math.sqrt(p * (p - this.x) * (p - this.y) * (p - this.z));
    	        return area;
    	    }
    
    	    /**
    	     * 展示三角形边长
    	     */
    	    public void showInfo(){
        
    	        System.out.println("三角形信息:");
    	        System.out.println("x边:" + this.x + " y边:" + this.y + " z边:" + this.z );
    	    }
    
    	    /**
    	     * 检查三边是否能组成三角形
    	     */
    	    public void check() throws NotSanjiaoException {
        
    	        //校验三条边长非负数
    	        if (this.x <= 0 || this.y <= 0 || this.z <= 0)
    	            throw new NotSanjiaoException("x边:" + this.x + " y边:" + this.y + " z边:" + this.z + " 不能构成三角形");
    
    	        //任意两边之和大于第三边
    			if ((this.x + this.y) <= this.z || (this.x + this.z) <= this.y || (this.y + this.z) <= this.x)
    				throw new NotSanjiaoException("x边:" + this.x + " y边:" + this.y + " z边:" + this.z + " 不能构成三角形");
    			//任意两边之差小于第三边
    			if ((this.x - this.y) >= this.z || (this.x - this.z) >= this.y || (this.y - this.z) >= this.x)
    				throw new NotSanjiaoException("x边:" + this.x + " y边:" + this.y + " z边:" + this.z + " 不能构成三角形");
    		}
    }

2.编写自定义异常

package org.example.exception;
    	
    	/**
    	 * 自定义异常类
    	 * 三边不能组成三角形异常
    	 */
    	public class NotSanjiaoException extends Exception{
        
    	
    	    public NotSanjiaoException() {
        
    	
    	    }
    	
    	    public NotSanjiaoException(String message) {
        
    	        super(message);
    	    }
    	
    	
    	
    	}

3.测试

package org.example;
    
    import org.example.bean.Sanj;
    import org.example.exception.NotSanjiaoException;
    
    import java.util.Scanner;
    
    public class Test {
        
        public static void main(String[] args) throws NotSanjiaoException {
        
            Scanner sc = new Scanner(System.in);
            System.out.println("输入第一条边边长：");
            int x = sc.nextInt();
            System.out.println("输入第二条边边长：");
            int y = sc.nextInt();
            System.out.println("输入第三条边边长：");
            int z = sc.nextInt();
            Sanj sanj = new Sanj(x,y,z);
            sanj.check();
            sanj.showInfo();
            double area = sanj.getArea();
            System.out.println("三角面积："+area);
        }
    
    }

[20200919225135302.png_pic_center]: https://img-blog.csdnimg.cn/20200919225135302.png#pic_center