Java基础复习---异常练习（二）:实现图形面积

package exceptiontest2;

/**
 * 
 *代码描述：
 *有一个圆Circle和长方形Rec
 *都可以获取图形的面积getArea()
 *对于计算面积过程中出现非法值value<0,视为出现问题
 *问题用异常NoValueException来描述，
 *且其继承RuntimeException
 * 流程代码和处理代码进行分离 
 * 
 * 
 * 不用if判断 
 * 因为if判断就算计算参数是错的，它会默认给length和high赋默认值0
 * 仍会面积计算
 * 但实际错误后应该进行提示，并不会调用getArea()
 * 问题用异常来解决
 * 
 * @author Administrator
 * 
 */
public class ExceptionTest2 {
	public static void main(String[] agrs) {

		// try {
		Rec r = new Rec(4, 4);
		// Rec p = new Rec(-4, 4);
		r.getArea();
		// p.getArea();
		// } catch (NoValueException e) {
		// // TODO Auto-generated catch block
		// System.out.println(e.toString());
		//
		// }
		Cicrle c = new Cicrle(-1);
		c.getArea();
		System.out.println("over");
	}

}

package exceptiontest2;

public class NoValueException extends RuntimeException {
	NoValueException(String message) {
		super(message);
	}
}

package exceptiontest2;

public interface Shape {

	public void getArea();
}

package exceptiontest2;

public class Rec implements Shape {
	private int length;
	private int high;

	Rec(int len, int hig) {// throws NoValueException {
		this.length = len;
		this.high = hig;
		if (length < 0 || high < 0)
			throw new NoValueException("输入非法值");
	}

	public void getArea() {
		// TODO Auto-generated method stub

		System.out.println(length * high);
	}

}

package exceptiontest2;

public class Cicrle implements Shape {
	private int radium;
	public static final double PI = 3.14;

	public Cicrle(int radium) {
		if (radium < 0)
			throw new NoValueException("非法");
		this.radium = radium;
	}

	@Override
	public void getArea() {
		// TODO Auto-generated method stub
		System.out.println(radium * radium * PI);
	}

}

参考文献：传智播客毕向东Java基础视频教程-day10-04-面向对象(异常-练习)