This chapter presents the following content: Using try and catch blocks to handle "Dangerous" method calls, numberformatexception, line plot example, try and catch blocks - more details, two types of exceptions - checked and unchecked, unchecked exceptions, checked exceptions,.and other contents. | Chapter 14 - Exception Handling Using try and catch Blocks to Handle "Dangerous" Method Calls NumberFormatException Line Plot Example try and catch Blocks - More Details Two Types of Exceptions - Checked and Unchecked Unchecked Exceptions Checked Exceptions Using API Documentation when Writing Exception-Handling Code When a try Block Throws Different Types of Exceptions The Exception Class and its getMessage Method Multiple catch blocks Understanding Exception Messages 1 Using try and catch Blocks to Handle "Dangerous" Method Calls Some API method calls are "dangerous" in that they might possibly lead to a runtime error. Example of a "safe" API method call (no runtime error possible): () Example of an API method call that might lead to a runtime error: () Technique for handling such runtime errors: Use exception handling. More specifically, surround the method call with a try block and insert a catch block immediately after the try block. 2 Using try and catch Blocks to Handle "Dangerous" Method Calls Syntax for try and catch blocks: try { } catch ( ) { } Example try and catch code fragment: try { quantity = (userEntry); } catch (NumberFormatException nfe) { ("Invalid quantity entered." + " Must be a whole number."); } Normally, one or more of these statements will be a "dangerous" API method call or constructor call. The exception class should match the type of exception that the try block might throw. 3 Using try and catch Blocks to Handle "Dangerous" Method Calls Semantics for previous slide's try and catch code fragment: If the userEntry string contains all digits, then: The int version of userEntry is assigned into quantity. The JVM skips the catch block and continues below it. If the userEntry string does not contain all digits, then: The parseInt method throws a NumberFormatException object. The | Chapter 14 - Exception Handling Using try and catch Blocks to Handle "Dangerous" Method Calls NumberFormatException Line Plot Example try and catch Blocks - More Details Two Types of Exceptions - Checked and Unchecked Unchecked Exceptions Checked Exceptions Using API Documentation when Writing Exception-Handling Code When a try Block Throws Different Types of Exceptions The Exception Class and its getMessage Method Multiple catch blocks Understanding Exception Messages 1 Using try and catch Blocks to Handle "Dangerous" Method Calls Some API method calls are "dangerous" in that they might possibly lead to a runtime error. Example of a "safe" API method call (no runtime error possible): () Example of an API method call that might lead to a runtime error: () Technique for handling such runtime errors: Use exception handling. More specifically, surround the method call with a try block and insert a catch block immediately after the
