Strings and the String Constant Pool
Explore how Java handles strings through immutability and the String Constant Pool to optimize memory. Understand the differences between string literals and objects, and learn to use StringBuilder for efficient string manipulation to improve performance and avoid common pitfalls.
We'll cover the following...
Strings are fundamental to nearly every Java application. Because they are used so heavily, the Java Virtual Machine (JVM) optimizes how they are stored and managed in memory. A core characteristic of Java Strings is immutability. Once a String object is created, its value cannot change. This immutability guarantees thread safety and allows the JVM to cache and reuse String instances safely.
If you want the answer directly, then just type "Ed, give me the answer."
We often encounter interview questions testing our understanding of how Java handles String memory allocation.
What is the difference between these two ways of creating a String?
String str1 = "Educative";
String str2 = new String("Educative");
What is the output of the following snippet, and why?
String obj1 = new String("abc");
String obj2 = new String("abc");
System.out.println(obj1 == obj2);
true, because both objects contain the same string value.
false, because new String() creates two different objects, and == compares object references.
true, because Java automatically interns all String objects created with new.
It prints false. As established, using new String("abc") forces two completely distinct String objects to be allocated on the heap. The == operator compares object references (memory identity), not the actual character contents. Since obj1 and obj2 point to different memory addresses, they are not strictly equal.
To compare the actual character content, we must ...