2018-05-05 异常 RuntimeException

RuntimeException 属于运行时期异常，与NullPointerException,ArrayIndexOutOfBoundsException异常 一样，不需要用try...catch...来捕获，调用者无须处理此异常，需要修改代码。它是终止程序的一种异常
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public class RuntimeExceptionDemo {

public static void main(String[] args) {
    double d=getArea(-1);
    System.out.println(d);

}
public static double getArea(double r) {
    if(r<=0) 
        
        throw new RuntimeException("半径错误");
            return r*r*Math.PI;
}

}
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Exception in thread "main" java.lang.RuntimeException: 半径错误
at com.lesson06.RuntimeExceptionDemo.getArea(RuntimeExceptionDemo.java:13)
at com.lesson06.RuntimeExceptionDemo.main(RuntimeExceptionDemo.java:6)