programming languages Online Quiz - 148

In Ruby, the << operator modifies a string in-place. Both name and name_copy reference the same string object, so mutating it affects both variables. After name << 't', the string becomes 'Steve Litt' and both variables show this modified value.

In Ruby, multiplying a string by an integer repeats it that many times. 'Cool ' * 3 produces 'Cool Cool Cool ' - the string repeats three times with spaces included.

The each block iterates over [1,2,3]. For each element i, it prints i*2 without separation. So it prints 2, then 4, then 6 on the same line: '246'. The print method doesn't add newlines automatically.

The while loop starts with i=0. It prints 0, then immediately hits 'break', which exits the loop. So only '0' is printed, matching the claimed output. The loop condition never gets re-evaluated.

Ruby variables can start with letters or underscores, but not digits. y2 is valid (starts with letter), _x is valid (starts with underscore), this_is_test is valid. 7x is invalid because it starts with a digit.

All four options are valid Ruby. (a) explicitly converts to strings before concatenation. (b) uses string interpolation #{}. (c) prints the sum 30 (valid). (d) prints x=10 (valid). Ruby allows puts of any object, calling to_s automatically.

The jspInit() method is called once during JSP initialization, has access to both ServletConfig and ServletContext (via config.getServletContext()), and can be overridden like other JSP lifecycle methods. All four statements are true.

The contentType attribute of the page directive defines the MIME type of the HTTP response. While the option contains a minor syntax typo (missing the @ character in the directive prefix), it correctly identifies contentType as the appropriate attribute, whereas type, mimetype, and language are invalid attributes.

JSP implicit objects include exception (available in error pages) and application (representing ServletContext). 'stream' is not a valid implicit object, and 'context' should be 'application' - the actual implicit object name.

Both jspInit() and jspDestroy() are JSP lifecycle methods that can be overridden to customize initialization and cleanup behavior. The _jspService method cannot be overridden as it's auto-generated by the container.

Scripting elements can be disabled at the application level using the element in the deployment descriptor (web.xml). They cannot be disabled programmatically via page directive - the isScriptingEnabled attribute does not exist for this purpose.

Under the JSP specification, tag files must end with either .tag or .tagx extensions. Distractors are incorrect because tag files are restricted to /WEB-INF/tags/ or /META-INF/tags/ inside JARs, can indeed be packaged in JAR files, and do not strictly require a TLD for mapping.

The getAttribute(String, int) method is the most efficient way to access an attribute when you know its scope because it bypasses scope searching. The int parameter is a scope constant (APPLICATION_SCOPE, SESSION_SCOPE, REQUEST_SCOPE, PAGE_SCOPE) that directly accesses the specified scope. getAttribute(String) without scope parameter searches all scopes sequentially, while findAttribute() also searches scopes. getPageContext() returns the PageContext object itself, not the attribute value.

In JSP custom tag handlers, getParent() returns the closest enclosing tag handler. This is part of the Tag and BodyTag interfaces. getAncestor(), findAncestor(), and findParent() are not standard methods in the JSP tag handler API. The getParent() method allows a nested tag to communicate with its parent tag, which is essential for cooperative tag handler patterns.

isUserInRole(String role) is used to check if the authenticated user belongs to a specified security role. The element in the DD maps a role name used in code (like isUserInRole calls) to an actual security role defined in the container. getUserPrincipal() returns the Principal object, getCookies() retrieves cookies, and getHeader() reads HTTP headers - none of these relate to role-based security reference mapping.

Form-based authentication requires a specific HTML form with action j_security_check, username field j_username, and password field j_password. The container requires this exact HTML structure to handle the authentication process. Basic, Digest, and Client Certificate authentication use HTTP headers or SSL certificates - they don't require application-provided HTML forms with specific action attributes.

The syntax <%-- ... --%> represents a JSP comment, which is processed entirely server-side and ignored during compilation, resulting in no output. The distractors are incorrect because they assume the code executes or outputs the string literal, which only occurs with scriptlets or expressions.

The Transfer Object pattern (also called Value Object) creates a serializable object containing multiple data items that can be sent to the client in a single method call instead of multiple fine-grained calls. This reduces network roundtrips between client and EJB. MVC is about separation of concerns, Business Delegate reduces coupling between presentation tier and business tier, and Intercepting Filter is about request/response preprocessing.

HttpServlet provides doGet(), doPost(), doHead(), doPut(), doDelete(), doOptions(), doTrace(), and do methods for other HTTP verbs. These are the standard service methods you override to handle specific HTTP request types. doError() is not a valid HttpServlet method - error handling is done through HttpServletResponse.sendError() or error-page configuration.