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String vs StringBuffer vs StringBuilder

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  • Amit Shekhar
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    Amit Shekhar
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String vs StringBuffer vs StringBuilder

I am Amit Shekhar, Co-Founder @ Outcome School, I have taught and mentored many developers, and their efforts landed them high-paying tech jobs, helped many tech companies in solving their unique problems, and created many open-source libraries being used by top companies. I am passionate about sharing knowledge through open-source, blogs, and videos.

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In this blog, we will learn about String, StringBuffer, and StringBuilder.

As we know, we have String, StringBuffer, and StringBuilder in both Java and Kotlin. So, whatever you are going to read now applies to both languages.

Let's begin.

String, StringBuffer, and StringBuilder are completely different. We need to know the difference to avoid misusing them. They serve different purposes, especially when it comes to mutability, thread-safe, and performance.

We will start with the String.

String

  • Mutability: String is immutable. A String can't be changed once it's made. If you change it, a new String object will be created.
  • Thread-Safe: Yes, being immutable, String is inherently thread-safe.
  • Performance: As the String is immutable, so it is slower for concatenation due to object creation. When we do frequent modifications, it can lead to performance issues due to the creation of many temporary objects.
  • Use case: Ideal for situations where strings don't require frequent modifications or when immutability is preferred.

Now that we have learned about the String, it's time to learn about the StringBuffer.

StringBuffer

  • Mutability: StringBuffer is mutable. As it is mutable, it can be modified after it is created.
  • Thread-Safe: Yes, it is thread-safe as its methods are synchronized. So, the advantage is that it can be used in multi-threaded environments.
  • Performance: More efficient than String for frequent modifications, but slower than StringBuilder due to synchronization overhead.
  • Use case: Ideal for situations where strings require frequent modifications in multi-threaded environments.

Perfect, now let's jump into the StringBuilder.

StringBuilder

  • Mutability: StringBuilder is mutable. As it is mutable, it can be modified after it is created.
  • Thread-Safe: No, it is not thread-safe as its methods are not synchronized. So, the disadvantage is that it can't be used in multi-threaded environments.
  • Performance: Most efficient for frequent string modifications in single-threaded environments.
  • Use case: Ideal for situations where strings require frequent modifications in single-threaded environments.

We now understand the differences between String, StringBuffer, and StringBuilder.

Let me tabulate the difference between String, StringBuffer, and StringBuilder.

FeatureStringStringBufferStringBuilder
MutabilityImmutable.Mutable.Mutable.
Thread-SafeYes.Yes.No.
PerformanceSlower for frequent modifications.More efficient than String for frequent modifications, but slower than StringBuilder due to synchronization overhead.Most efficient for frequent string modifications in single-threaded environments.
Use caseIdeal for situations where strings don't require frequent modifications or when immutability is preferred.Ideal for situations where strings require frequent modifications in multi-threaded environments.Ideal for situations where strings require frequent modifications in single-threaded environments.

This was all about String, StringBuffer, and StringBuilder.

Prepare yourself for Android Interview: Android Interview Questions

That's it for now.

Thanks

Amit Shekhar
Co-Founder @ Outcome School

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