In JDBC, the CallableStatement interface is used to execute SQL stored procedures. It allows you to call stored procedures that may take parameters and return values. Statement is used for executing regular SQL statements, Connection is used for establishing database connections, and PreparedStatement is used for executing parameterized SQL queries.

In Java, the BigDecimal data type is used to store decimal numbers with precision up to 15 decimal places. It is commonly used in financial and scientific applications where high precision is required. The float and double types have limited precision and are not suitable for this purpose.

The Externalizable interface in Java extends the ObjectInput and ObjectOutput interfaces and adds two methods into it: writeExternal and readExternal. These methods are used for customized serialization of objects. The other options are not related to the Externalizable interface.

Lambda expressions were introduced in Java 8. They are a significant feature that simplifies the syntax for writing anonymous functions and enhances the readability and conciseness of code in Java.

The correct answer is "URI." In Java, the URI class is used to represent a Uniform Resource Identifier. It's designed to handle the complete URI syntax, including components like scheme, authority, path, query, and fragment. A URI is a broader concept that includes URLs (Uniform Resource Locators) and URNs (Uniform Resource Names).

In Java, the submit method of the ExecutorService interface is used to submit a Callable task and returns a Future object representing the result of the computation. This method is commonly used for asynchronous tasks that return results.

Lambda expressions eliminate the need for anonymous inner classes. Before lambda expressions were introduced in Java, anonymous inner classes were used to implement single-method interfaces, like Runnable or ActionListener. Lambda expressions provide a more concise and expressive way to define such implementations, reducing the verbosity of code.

It uses type conversion to promote one of the operands to the type of the other operand, and then performs the operation. For example, if you add a string and an int, the int is converted to a string, and string concatenation is performed. If you add two integers, normal addition is performed.

In a text editor, where efficient memory and performance management are crucial, StringBuilder is used for in-place string manipulation, and WeakReference helps in memory management by allowing objects to be garbage collected when not strongly referenced. StringBuffer is thread-safe but may not provide the best performance. The other options are not suitable for such scenarios.

When the join() method is called on a thread in Java, the calling thread will wait for the specified thread to finish its execution. This is often used to ensure that a thread completes its task before the calling thread proceeds. It's a mechanism for thread synchronization.