Exception handling in java

Exception handling in java

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  Exception Handling In Java ByPriyanka zope
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  Content 1:Introduction. 2:Error and ErrorHandling. 3:Exception. 4:Type Of Exception. 5:Coding Exception. 6:Advantages
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  Error and ErrorHandling. v An Error is any unexpected result obtained from a program during execution. v Unhandled errors may manifest themselves as incorrect results or behavior, or as abnormal program termination. v Errors should be handled by the programmer, to prevent them from reaching the user.
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  Exception Exception- a bettererror handling. Exception – an error condition that can occur during the course of a program execution Ø In Java, exceptions are objects themselves Exception handling is another form of control structure (like ifs and switch statements) Ø When an error is encountered, the normal flow of the program is stopped and the exception is Handled.
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  Types Of Exception I:CheckedException Checked at compile time. II:Unchecked Exception Checked at runtime.
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  Coding Exception 1: try…..catchblock 2:finally 3: throw
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  Try…catch block • To processan exception when it occurs, the line that throws the exception is executed within a try block. • A try block is followed by one or more catch clauses, which contain code to process an exception. • The catch statement is used for catching exceptions. try { <try block> } catch ( <ExceptionClass> <name> ) { <catch block> } catch ( <ExceptionClass> <name> ) { <catch block>}
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  Finally clause • A trystatement can have an optional clause designated by the reserved word finally. • If no exception is generated, the statements in the finally clause are executed after the statements in the try block complete. try { // statements that throw exceptions } catch(<exception>) { // do stuff } finally { – // code here runs whether or not catch runs }
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  Throw All methods usethe throw statement to throw an exception. The throw statement requires a single argument: a throwable object. Throwable objects are instances of any subclass of the Throwable class. Here's an example of a throw statement.
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  Problem IllegalArgumentException: illegal parameter value Problem publicclass BankAccount { public void withdraw(double amount) { if (amount > balance) { ????????? } balance = balance - amount; } . . .}
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  Solution public class BankAccount { publicvoid withdraw(double amount) { if (amount > balance) { IllegalArgumentException exception = new IllegalArgumentException("Amount exceeds balance"); throw exception; } balance = balance - amount; } . . . }
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  Advantages 1:Separating Error-Handling Codefrom "Regular" Code 2:Grouping and Differentiating Error Types 3:consistency 4:flexibility 5:simplicity