Java HF Chapter 1

What is Java famous for regarding backward compatibility?

• Old code can run happily on new JVMs
• Old code requires complete rewriting
• New code cannot run on old JVMs
• Backward compatibility is not a concern

Answer explanation

Java is famous for its backward compatibility, allowing old code to run happily on new JVMs.

What is mentioned as a characteristic of Java code in the "real world"?

• Older coding styles
• Only using the newest coding styles
• No variation in coding styles
• Complete absence of older code

Answer explanation

In the "real world," Java code often includes older coding styles.

What does the text mention about the growth of the Java API over the years?

• It remained stagnant
• No significant growth
• It decreased
• It grew enormously

Answer explanation

The Java API grew enormously over the years.

What is the best estimate provided for the number of lines of Java code written in the last 25 years?

• 100 trillion
• 50 billion
• Over 17 gazillion
• 5 million

Answer explanation

The best estimate is that over 17 gazillion lines of Java code have been written in the last 25 years.

What is one of Java's super-powers mentioned in the text?

• High-speed execution
• Memory optimization
• Backward compatibility
• Java Virtual Machine (JVM)

Answer explanation

Java's JVM can optimize code while it's running, contributing to its speed.

In terms of speed, how does Java compare to languages like C and Rust according to the text?

• Java is faster than both C and Rust.
• Java is slower than both C and Rust.
• Java is as fast as C and Rust.
• Java's speed is not mentioned in relation to C and Rust.

Answer explanation

Java is considered very fast, almost as fast as languages like C and Rust.

What is mentioned as a downside of Java compared to languages like C and Rust?

• Java lacks backward compatibility.
• Java has a confusing versioning system.
• Java is slower in terms of execution speed.
• Java use lot of memory

Answer explanation

The text mentions that Java uses a lot of memory compared to C and Rust.

What is the official version number format for Java from version 9 onward, according to the text?

• Java 9, Java 10, Java 11, etc.
• Java 1.9, Java 1.10, Java 1.11, etc.
• Java SE 9, Java SE 10, Java SE 11, etc.
• Java 1.x, where x is the version number.

Answer explanation

The official version number format from Java 9 onward is just the number, without the “1” prefix.

In this book, what convention will be used for version numbers from Java 1.0 to Java 1.4?

• Java 1.0–1.4
• Java 0.1–0.4
• Java 01.0–01.4
• Java 1–4

Answer explanation

In this book, the convention used for version numbers is Java 1.0–1.4.

What is the reason mentioned for dropping the “1” prefix from version numbers starting from Java 5 onward?

• To align with the common convention.
• To make version numbers shorter.
• To simplify the naming conventions.
• To confuse developers.

Answer explanation

The “1” prefix was dropped to simplify the naming conventions and align with the common convention.