Will the Guru

Primitive type vs Reference type

• Primitives are stored on stack while the other is on heap.
• Primitive types are mostly faster
• https://www.baeldung.com/java-primitives-vs-objects

BigDecimal vs Double

• BigDecimal requires more precision which consumes more resources

StringBuilder vs String literal

• StringBuilder always shows better performance
• If the String literals concatenation is in one line, JVM automatically optimizes it which results in the same performance as StringBuilder
  • ex) "Hello" + str1 + "World" + str2
    almost equals to
    StringBuilder sb = new StringBuilder();
sb.append("Hello");
sb.append(str1);
sb.append("World");
sb.append(str2);
    

Reference

• https://www.udemy.com/course/java-application-performance-and-memory-management/