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Unchecked exceptions : * represent defects in the program (bugs) - often invalid arguments passed to a non-private method. To quote from The Java Programming Language, by Gosling, Arnold, and Holmes : "Unchecked runtime exceptions represent conditions that, generally speaking, reflect errors in your program's logic and cannot be reasonably recovered from at run time." * are subclasses of RuntimeException, and are usually implemented using IllegalArgumentException, NullPointerException, or IllegalStateException * a method is not obliged to establish a policy for the unchecked exceptions thrown by its implementation (and they almost always do not do so) Checked exceptions : * represent invalid conditions in areas outside the immediate control of the program (invalid user input, database problems, network outages, absent files) * are subclasses of Exception * a method is obliged to establish a policy for all checked exceptions thrown by its implementation (either pass the checked exception further up the stack, or handle it somehow) It is somewhat confusing, but note as well that RuntimeException (unchecked) is itself a subclass of Exception (checked).
What else can I help you with?
What is unchecked exception?
A checked exception is an exception which the Java source code must deal with, either by catching it or declaring it to be thrown. Unchecked exceptions are all exceptions which do not follow this rule. When an unchecked exception is thrown, it is usually caused by a misuse of code - passing a null or otherwise incorrect argument. This includes classes like NullPointerException and IllegalArgumentException. Checked exceptions are generally caused by faults outside of the code itself - missing resources, networking errors, and problems with threads come to mind. These could include subclasses of FileNotFoundException, UnknownHostException, etc. The Java documentation (link below) gives some loose guidelines to follow when trying to decide which type of exception to use: "If a client can reasonably be expected to recover from an exception, make it a checked exception. If a client cannot do anything to recover from the exception, make it an unchecked exception." From a purely code-oriented point of view, a checked exception is a subclass of Exception, while an unchecked exception is a subclass of RuntimeException.
Is it essential to catch all the exceptions and justify your answer?
Checked exceptions should be caught. Otherwise, compile errors are generated.
What is Throwable?
In Java, Throwable is the superclass of all errors and exceptions, representing conditions that a program should ideally handle. It has two main subclasses: Error, which indicates serious problems that a reasonable application should not catch (like out-of-memory errors), and Exception, which represents conditions that a program can catch and handle. By extending Throwable, both checked and unchecked exceptions can be defined, allowing for robust error handling in Java applications.
Describe the JAVA throwable class hierarchy and types of exceptions?
In Java there are two main types of Exceptions. * Checked Exceptions - The ones that can be checked & handled in our code. Ex: I/O Exception, SQL Exception etc. In most cases, the compiler itself forces us to catch & handle these exceptions * Un-checked Exceptions - The ones that we cannot & should not handle in our code. Ex. Null Pointer Exception The java.lang.Throwable is the super class of all errors and exceptions in Java. Only objects of this class can be thrown & caught and handled by try-catch blocks. Ex: try { ..... ..... } catch (Exception e){ ... } finally { ... }
If a method calls another method and that method throw an exception then caller method must be throw that exception or not?
If method A calls method B and method B throws an exception, then method A must handle that exception. It does not have to throw the exception if it is in a try-catch block, but it must do something to deal with it.Note that this only applies to checked exceptions. If method B throws an unchecked exception, then A is allowed to ignore it.
What are the types of exception in java?
Exceptions are of two types: checked exceptions and unchecked exceptions.
Difference between checked and unchecked exception?
Checked exceptions are exceptions which need to be handled explicitly. These are the ones which require a try-catchblock or a throws keyword.Unchecked exceptions are exceptions which have no obligation to be handled. A NullPointerException is one common example.
What are the different types of exception?
Exceptions in programming can be categorized into several types, primarily into checked and unchecked exceptions. Checked exceptions are those that must be either caught or declared in the method signature, such as IOException in Java. Unchecked exceptions, like NullPointerException, do not require explicit handling and typically indicate programming errors. Additionally, there are system exceptions related to runtime issues and user-defined exceptions that developers create for specific application needs.
What is unchecked exception?
A checked exception is an exception which the Java source code must deal with, either by catching it or declaring it to be thrown. Unchecked exceptions are all exceptions which do not follow this rule. When an unchecked exception is thrown, it is usually caused by a misuse of code - passing a null or otherwise incorrect argument. This includes classes like NullPointerException and IllegalArgumentException. Checked exceptions are generally caused by faults outside of the code itself - missing resources, networking errors, and problems with threads come to mind. These could include subclasses of FileNotFoundException, UnknownHostException, etc. The Java documentation (link below) gives some loose guidelines to follow when trying to decide which type of exception to use: "If a client can reasonably be expected to recover from an exception, make it a checked exception. If a client cannot do anything to recover from the exception, make it an unchecked exception." From a purely code-oriented point of view, a checked exception is a subclass of Exception, while an unchecked exception is a subclass of RuntimeException.
Is it essential to catch all the exceptions and justify your answer?
Checked exceptions should be caught. Otherwise, compile errors are generated.
What is Throwable?
In Java, Throwable is the superclass of all errors and exceptions, representing conditions that a program should ideally handle. It has two main subclasses: Error, which indicates serious problems that a reasonable application should not catch (like out-of-memory errors), and Exception, which represents conditions that a program can catch and handle. By extending Throwable, both checked and unchecked exceptions can be defined, allowing for robust error handling in Java applications.
Describe the JAVA throwable class hierarchy and types of exceptions?
In Java there are two main types of Exceptions. * Checked Exceptions - The ones that can be checked & handled in our code. Ex: I/O Exception, SQL Exception etc. In most cases, the compiler itself forces us to catch & handle these exceptions * Un-checked Exceptions - The ones that we cannot & should not handle in our code. Ex. Null Pointer Exception The java.lang.Throwable is the super class of all errors and exceptions in Java. Only objects of this class can be thrown & caught and handled by try-catch blocks. Ex: try { ..... ..... } catch (Exception e){ ... } finally { ... }
What is checked exception?
A compiler for the Java programming language checks, at compile time, that a program contains handlers for checked exceptions, by analyzing which checked exceptions can result from execution of a method or constructor. For each checked exception which is a possible result, the throws clause for the method or constructor must mention the class of that exception or one of the superclasses of the class of that exception. This compile-time checking for the presence of exception handlers is designed to reduce the number of exceptions which are not properly handled.
What is the default property of a checkbox?
The default property of a checkbox is its state, which can be either checked or unchecked. When a checkbox is set to checked, it indicates that the option is selected, while an unchecked state means it is not selected. Additionally, a checkbox can be set to a default state when the page loads, allowing developers to pre-select options based on user preferences or requirements. The default behavior can be controlled through HTML attributes like "checked" for default selection.
Can any one please give some example of caught-exceptions and uncaught-exceptions in java?
// Open a reader from standard in... final BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); try { // BufferedReader.readLine can throw an IOException, which is a checked exception. // So we need to catch it. String str = in.readLine(); // Integer.valueOf throws a NumberFormatException, which is an unchecked exception. // Note that we don't need to catch this. int num = Integer.parseInt(str); } catch (final IOException ex) { }
If you block a picture by mistake in FACEBOOK how do you unblock it?
here's what to do:1- Click 'Tools' in the bar on top.2- Click 'Options' from the Tools button3- Click 'Content'4- If the 'Load Images Automatically' checkbox is unchecked, check it.or, If it is already checked, click 'Exceptions' and click 'Remove all sites'after that, Close it and the pictures can load perfectly in facebook.
How do you uncheck a checked box?
To uncheck a checked box, simply click on the box again with your mouse or tap it if you're using a touchscreen device. This action toggles the state of the checkbox from checked to unchecked. If you're using a keyboard, you can also navigate to the checkbox and press the spacebar to change its state.
