scala中捕获异常

Scala的例外 (Exceptions in Scala)

Exceptions are cases or events that occur in the program at run time and hinder the regular flow of execution of the program. These can be handled in the program itself.

例外是在运行时在程序中发生并阻碍程序正常执行流程的情况或事件。 这些可以在程序本身中处理。

Scala also provides some methods to deal with exceptions.

Scala还提供了一些处理异常的方法。

When the program's logic is probable to throw an exception, it has to be declared that such an exception might occur in the code, and a method has to be declared that catches the exception and works upon it.

当程序的逻辑可能引发异常时，必须声明该异常可能在代码中发生，并且必须声明一个捕获异常并对其进行处理的方法。

如何抛出异常？ (How to throw exception?)

In Scala, the throw keyword is used to throw an exception and catch it. There are no checked exceptions in Scala, so you have to treat all exceptions as unchecked exceptions.

在Scala中， throw关键字用于引发异常并捕获它。 Scala中没有检查异常，因此您必须将所有异常视为未检查异常。

Also read, Java | checked and unchecked exceptions

另请阅读Java 已检查和未检查的异常

Syntax:

句法：

    throw exception object

To throw an exception using the throw keyword we need to create an exception object that will be thrown.

要使用throw关键字引发异常，我们需要创建一个将被引发的异常对象。

Example 1:

范例1：

In this example, we will throw an exception if the speed will be above 175KmpH.

在此示例中，如果速度高于175KmpH，则将引发异常。

object MyObject {
def checkSpeed(speed : Int ) = {
if (speed > 175)
throw new ArithmeticException("The rider is going over the speed Limit!!!")
else 
println("The rider is safe under the speed Limit.")
}
def main(args: Array[String]) {
checkSpeed(200)
}
}

Output:

输出：

java.lang.ArithmeticException: The rider is going over the speed Limit!!!
...

Explanation:

说明：

In the above code, we have declared a function checkSpeed() that takes the speed of the bike and check if it’s above the speed limit which is 175. If the speed is above 175 it throws an Arithmetic exception that says "The rides is going above the speed limit!!!". Else it prints "The rider is safe under the speed limit".

在上面的代码中，我们声明了一个函数checkSpeed()来获取自行车的速度，并检查其是否超过了175的速度限制。如果速度超过175，则会引发算术异常， 该异常表示“骑车正在行驶超过速度限制！！！” 。 否则将打印“在速度限制下骑手很安全” 。

Example 2:

范例2：

In this example, we will learn to throw an exception and catch it using the try-catch block.

在此示例中，我们将学习引发异常并使用try-catch块捕获该异常。

object MyObject {
def isValidUname(name : String ) = {
throw new Exception("The user name is not valid!")
}
def main(args: Array[String]) {
try {
isValidUname("Shivang10");
}
catch{
case ex : Exception => println("Exception caught : " + ex)
}
}
}

Output:

输出：

Exception caught : java.lang.Exception: The user name is not valid!

Exception:

例外：

In the above code, we have a function isValidUname() that throws an exception which is caught by the catch block in the main function.

在上面的代码中，我们有一个函数isValidUname() ，该函数引发一个异常，该异常由主函数中的catch块捕获。

翻译自: https://www.includehelp.com/scala/how-to-throw-exception.aspx

scala中捕获异常