checked-exceptions

问题 This question already has answers here : Java 8 Lambda function that throws exception? (26 answers) Closed 4 years ago . I have the following code snippet. package web_xtra_klasa.utils; import java.util.Arrays; import java.util.Properties; import java.util.function.Function; import javax.mail.Message; import javax.mail.MessagingException; import javax.mail.Session; import javax.mail.Transport; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; public class

问题 A few of my methods in Java throw exceptions such as NoSuchElementException, IllegalArgumentException, etc. But when using these methods, these exceptions appear to be unchecked. In other words, caller of my methods is not required to do a try/catch on my methods that throw those exceptions. I read around it seems that Exceptions by default are "checked" and only Errors are the ones "unchecked". But somehow, the exceptions I throw are also unchecked. It is weird. How can I ensure that when my

问题 A few of my methods in Java throw exceptions such as NoSuchElementException, IllegalArgumentException, etc. But when using these methods, these exceptions appear to be unchecked. In other words, caller of my methods is not required to do a try/catch on my methods that throw those exceptions. I read around it seems that Exceptions by default are "checked" and only Errors are the ones "unchecked". But somehow, the exceptions I throw are also unchecked. It is weird. How can I ensure that when my

问题 I noticed by accident that this throw statement (extracted from some more complex code) compiles: void foo() { try { } catch (Throwable t) { throw t; } } For a brief but happy moment I thought that checked exceptions had finally decided to just die already, but it still gets uppity at this: void foo() { try { } catch (Throwable t) { Throwable t1 = t; throw t1; } } The try block doesn't have to be empty; it seems it can have code so long as that code doesn't throw a checked exception. That

问题 This question already has answers here : Java 8 Lambda function that throws exception? (24 answers) Closed 4 years ago . Given this java 8 code public Server send(String message) { sessions.parallelStream() .map(Session::getBasicRemote) .forEach(basic -> { try { basic.sendText(message); } catch (IOException e) { e.printStackTrace(); } }); return this; } how do we properly make this IOException be delegated up the stack of the method call? (in nutshell how to make this method throw this

问题 This question already has answers here : Java 8 Lambda function that throws exception? (24 answers) Closed 4 years ago . Given this java 8 code public Server send(String message) { sessions.parallelStream() .map(Session::getBasicRemote) .forEach(basic -> { try { basic.sendText(message); } catch (IOException e) { e.printStackTrace(); } }); return this; } how do we properly make this IOException be delegated up the stack of the method call? (in nutshell how to make this method throw this

问题 I've studied that: With an unchecked exception, however, the compiler doesn't force client programmers either to catch the exception or declare it in a throws clause. In fact, client programmers may not even know that the exception could be thrown. eg, StringIndexOutOfBoundsException thrown by String's charAt() method. what its mean? according to that code there is no need to put try catch block in code, but i've seen compiler forces to put the code in try catch block. I'm very confused what

问题 I'm playing with the new lambda features in Java 8, and found that the practices offered by Java 8 are really useful. However, I'm wondering is there a good way to make a work-around for the following scenario. Suppose you have an object pool wrapper that requires some kind of a factory to fill the object pool, for example (using java.lang.functions.Factory ): public class JdbcConnectionPool extends ObjectPool<Connection> { public ConnectionPool(int maxConnections, String url) { super(new

问题 I'm playing with the new lambda features in Java 8, and found that the practices offered by Java 8 are really useful. However, I'm wondering is there a good way to make a work-around for the following scenario. Suppose you have an object pool wrapper that requires some kind of a factory to fill the object pool, for example (using java.lang.functions.Factory ): public class JdbcConnectionPool extends ObjectPool<Connection> { public ConnectionPool(int maxConnections, String url) { super(new

问题 This question already has answers here : Understanding checked vs unchecked exceptions in Java (21 answers) Closed 3 years ago . I want to know how does one know to create and throw a checked exception or an unchecked exception. For example I have a service which takes some data and validates it before using it. During validation a certain field did not meet the rules and I want to throw an exception say ValidationException(). How will I know of decide it should be checked or unchecked. In