difference between throw and throws java

Exception handling : Difference between throw vs throws in Java

stackoverflow.com › questions › 72521281 › exception-handling-difference-between-throw-vs-throws-in-java

throws tells others that this method can throw an exception. Think of it as documentation. Checked exceptions must be part of a method's signature.

throw actually throws the exception. (throw new Exception(); first creates a new exception instance and then throws that instance. You could use two separate statements: Exception ex = new Exception(); throw ex;) You can throw both checked and unchecked exceptions with the throw keyword.

void checked() throws Exception { // required, Exception is a checked exception
  throw new Exception();
}

void unchecked() {
  throw new RuntimeException(); // throws not required, RuntimeException is not checked
}

void checkedCall() throws Exception {
  checked(); // throws required, because "checked" can throw a checked exception
}

void caught() {
  try {
    checked();
  } catch (final Exception ex) {
    // throws is no longer required, because the (checked) exception is handled within the method itself. It never leaves the method.
  }
}

Regarding your updated question: you don't throw new ArithmeticException, because it is thrown by the JVM when it tries to apply the / operator. You can throw it manually if you want to, but that's just redundant code.

Answer from knittl on Stack Overflow

Unstop

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Top 10 Key Differences Between Throw Vs. Throws In Java // Unstop

February 10, 2025 - In Java, throw is used to trigger exceptions, while throws declares them in a method. throw is inside methods; throws lists potential exceptions.

GeeksforGeeks

geeksforgeeks.org › java › difference-between-throw-and-throws-in-java

Difference Between throw and throws in Java

July 11, 2025 - You create an exception object and use throw to signal that an error has occurred. Used to manually throw an exception. Used inside a method. Can throw only one exception at a time.

Discussions

oop - Exception handling : Difference between throw vs throws in Java - Stack Overflow

Could someone explain me when it is useful to use the keyword throw new .. instead of using throws next to the signature of a method ? I know that when a method throws a Checked Exception. Java for... More on stackoverflow.com

stackoverflow.com

[Java] ELI5: the difference between "throws" and "throw"

Use "throw" to actually throw an exception. Tag a method "throws [exception type]" to declare that that exception can be thrown by the method; if it's a checked exception the calling method will either have to catch the exception, or pass it up the call chain further by also declaring "throws [whatever]". Checked exceptions are for potential problems that are impossible for the program to anticipate; unchecked (runtime) exceptions are for bugs in the code. So NullPointerException is unchecked because you should write your code such that you never try to dereference null, but IOException is checked because if someone else deletes a file while you're reading it, there's nothing your code could do to prevent that. You use try/catch blocks to deal with a checked exception when you're at a point where you can do something sensible: Preferences prefs; File prefsFile; try { } catch (IOException e) { Dialog.error("Error trying to read from the preferences file, using default preferences instead"); prefs = Preferences.getDefaultPreferences(); } More on reddit.com

r/learnprogramming

2

1

June 6, 2014

ELI5: The difference between "throws" and "throw"

Throw is used when you want to say "here's an exception, someone take care of it". Throws is used to tag methods as "these exceptions may occur here". You would use try/catch/finally blocks when you're dealing with methods that can have exceptions (for example, I/O like reading a file, socket, or database) and/or when you want to handle that exceptional situation ("when there's a problem reading this file, I'll create a log entry and stop the process" or "if there's an issue reading from the database, write the SQL to the console"). The finally is used for the "no matter what happens, I need to clean up after myself", such as closing files, database connections, etc. The try-with-resources is another possibility here (catch and finally are both optional based on necessity) that will handle the cleanup automatically (an implicit finally that closes the resource). More on reddit.com

r/javahelp

5

2

January 26, 2015

JAVA throws and throw?

Exceptions that are not a subclass of RuntimeException must be explicitly handled in Java. That way, you won't be surprised if someone forgets to put it in the comment or you forget to read the comment thoroughly. If your method calls a method that throws a particular exception, it's a compiler error unless you either catch the exception or declare that you throw that exception (which in turn forces any method that calls this method to deal with it). More on reddit.com

r/learnprogramming

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May 17, 2021

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