1Z0-811 Primitives, Strings and Operators Practice Question
You are developing a high-frequency trading application where performance is critical. You need to parse and concatenate trade messages. The messages are received as strings and must be combined into a single output string for logging. Each message is appended to the log string. Currently, you are using String concatenation with the '+' operator inside a loop that processes up to 10,000 messages per second. However, performance monitoring shows that the application experiences frequent garbage collection pauses, affecting throughput. Which approach should you take to reduce garbage collection overhead and improve performance?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use StringBuilder instead of String concatenation, ensuring that the StringBuilder is created with an appropriate initial capacity.
StringBuilder is designed for efficient string concatenation without synchronization overhead. Creating it with an appropriate initial capacity further reduces reallocations. StringBuffer is thread-safe but adds unnecessary overhead in a single-threaded context. String.concat() still creates new objects. Increasing heap size only delays GC, not reduce object creation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use StringBuilder instead of String concatenation, ensuring that the StringBuilder is created with an appropriate initial capacity.
Why this is correct
Reduces object creation and GC pressure.
- ✗
Use the String.concat() method for each concatenation to reduce object creation.
Why it's wrong here
Still creates new String objects.
- ✗
Use StringBuffer instead of String concatenation because it is thread-safe and efficient.
Why it's wrong here
Synchronization overhead unnecessary for single-threaded.
- ✗
Keep using the '+' operator but increase the heap size to reduce garbage collection frequency.
Why it's wrong here
Does not address excessive object creation.
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