我们可以在Java的静态块中抛出未检查异常吗?
静态块是一段带有static关键字的代码块。通常,它们用于初始化静态成员。JVM在类加载时,在main方法之前执行静态块。
示例
public class MyClass { static{ System.out.println("Hello this is a static block"); } public static void main(String args[]){ System.out.println("This is main method"); } }
输出
Hello this is a static block This is main method
静态块中的异常
就像Java中的任何其他方法一样,当静态块中发生异常时,可以使用try-catch对来处理它。
示例
import java.io.File; import java.util.Scanner; public class ThrowingExceptions{ static String path = "D://sample.txt"; static { try { Scanner sc = new Scanner(new File(path)); StringBuffer sb = new StringBuffer(); sb.append(sc.nextLine()); String data = sb.toString(); System.out.println(data); } catch(Exception ex) { System.out.println(""); } } public static void main(String args[]) { } }
输出
This is a sample fileThis is main method
在静态块中抛出异常
每当你抛出一个检查异常时,你需要在当前方法中处理它,或者你可以将其抛出(推迟)到调用方法。
You cannot use throws keyword with a static block, and more over a static block is invoked at compile time (at the time of class loading) no method invokes it.
因此,如果你在静态块中使用throw关键字抛出异常,则必须将其包装在try-catch块中,否则将生成编译时错误。
示例
import java.io.FileNotFoundException; public class ThrowingExceptions{ static String path = "D://sample.txt"; static { FileNotFoundException ex = new FileNotFoundException(); throw ex; } public static void main(String args[]) { } }
编译时错误
ThrowingExceptions.java:4: error: initializer must be able to complete normally static { ^ ThrowingExceptions.java:6: error: unreported exception FileNotFoundException; must be caught or declared to be thrown throw ex; ^ 2 errors
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