It depends on whether you can deal with the exceptions that can be raised at this point or not.
If you can handle the exceptions locally you should, and it is better to handle the error as close to where it is raised as possible.
If you can't handle them locally then just having a try / finally block is perfectly reasonable - assuming there's some code you need to execute regardless of whether the method succeeded or not. For example (from Neil's comment), opening a stream and then passing that stream to an inner method to be loaded is an excellent example of when you'd need try { } finally { }, using the finally clause to ensure that the stream is closed regardless of the success or failure of the read.
However, you will still need an exception handler somewhere in your code - unless you want your application to crash completely of course. It depends on the architecture of your application exactly where that handler is.
Answer from ChrisF on Stack ExchangeIt depends on whether you can deal with the exceptions that can be raised at this point or not.
If you can handle the exceptions locally you should, and it is better to handle the error as close to where it is raised as possible.
If you can't handle them locally then just having a try / finally block is perfectly reasonable - assuming there's some code you need to execute regardless of whether the method succeeded or not. For example (from Neil's comment), opening a stream and then passing that stream to an inner method to be loaded is an excellent example of when you'd need try { } finally { }, using the finally clause to ensure that the stream is closed regardless of the success or failure of the read.
However, you will still need an exception handler somewhere in your code - unless you want your application to crash completely of course. It depends on the architecture of your application exactly where that handler is.
The finally block is used for code that must always run, whether an error condition (exception) occurred or not.
The code in the finally block is run after the try block completes and, if a caught exception occurred, after the corresponding catch block completes. It is always run, even if an uncaught exception occurred in the try or catch block.
The finally block is typically used for closing files, network connections, etc. that were opened in the try block. The reason is that the file or network connection must be closed, whether the operation using that file or network connection succeeded or whether it failed.
Care should be taken in the finally block to ensure that it does not itself throw an exception. For example, be doubly sure to check all variables for null, etc.
This is useful if you want the currently executing method to still throw the exception while allowing resources to be cleaned up appropriately. Below is a concrete example of handling the exception from a calling method.
public void yourOtherMethod() {
try {
yourMethod();
} catch (YourException ex) {
// handle exception
}
}
public void yourMethod() throws YourException {
try {
db.store(mydata);
} finally {
db.cleanup();
}
}
It's there because the programmer wanted to make sure that db.cleanup() is called even if the code inside the try block throws an exception. Any exceptions will not be handled by that block, but they'll only be propagated upwards after the finally block is executed. The finally block will also be executed if there was no exception.
Java Try Catch Finally blocks without Catch - Stack Overflow
Need help solving 'try' without 'catch', 'finally' or resource declarations error.
Is there a "try" without "catch" in Javascript?
java - Why write Try-With-Resources without Catch or Finally? - Stack Overflow
If any of the code in the try block can throw a checked exception, it has to appear in the throws clause of the method signature. If an unchecked exception is thrown, it's bubbled out of the method.
The finally block is always executed, whether an exception is thrown or not.
A small note on try/finally: The finally will always execute unless
System.exit()is called.- The JVM crashes.
- The
try{}block never ends (e.g. endless loop).
I keep receiving this error: 'try' without 'catch', 'finally' or resource declarations. I’ve tried to add and remove curly brackets, add final blocks, and catch blocks and nothing is working.
https://codepen.io/angelineb/pen/KKQpbqV
I want to try action A, and if it fails try action B, and if it fails, try action C. I need to do that without having to specify a "catch". Is that possible? Thanks!
As explained above this is a feature in Java 7 and beyond. try with resources allows to skip writing the finally and closes all the resources being used in try-block itself. As stated in Docs
Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable, can be used as a resource.
See this code example
static String readFirstLineFromFile(String path) throws IOException {
try (BufferedReader br = new BufferedReader(new FileReader(path))) {
return br.readLine();
}
}
In this example the resource is BufferReader object as the class implements the interface java.lang.AutoCloseable and it will be closed whether the try block executes successfully or not which means that you won't have to write br.close() explicitly.
Another important thing to notice here is that if you are writing the finally block yourself and both your try and finally block throw exception then the exception from try block is supressed.
While on the other hand if you are using try-with-resources statement and exception is thrown by both try block and try-with-resources statement then in this case the exception from try-with-resources statement is suppressed.
As the @Aaron has answered already above I just tried to explain you. Hope it helps.
Source: http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
This is a new feature in Java 7 and beyond. Without this, you'd need a finally block which closes the resource PrintWriter out. So the code above is equivalent to:
PrintWriter out = null;
try {
PrintWriter out = ...
} finally {
if(null != out) {
try {
out.close();
} catch(Exception e) {} // silently ignore!
}
}
See The try-with-resources Statement
finally should have atleast a try block, catch is optional. The point of finally blocks is to make sure stuff gets cleaned up whether an exception is thrown or not. As per the JLS
A finally clause ensures that the finally block is executed after the try block and any catch block that might be executed, no matter how control leaves the try block or catch block.
Hence a finally should always be preceded by a try block.
You must have a try block with a finally block. The try block defines which lines of code will be followed by the finally code. If an exception is thrown prior to the try block, the finally code will not execute.
Adding catch blocks is optional:
try {
// something
} finally {
// guaranteed to run if execution enters the try block
}