Java String Comparison: `==` vs. `.equals()` – When to Use Which?

Object Reference Comparison vs. Value Equality in Java

In Java, determining object equality can be confusing when comparing strings using the == operator. Let's delve into this seemingly ambiguous behavior.

Consider the following scenario:

// Define a String array
String[] parts = {"231", "CA-California", "Sacramento-155328", "aleee", "Customer Service Clerk", "Alegra Keith.doc.txt"};

// Perform comparison
if ("231" == parts[0]) {
    // This comparison will evaluate to false
}

Surprisingly, the comparison returns false. This is because the == operator in Java checks for object reference equality, not value equality. Unlike in many other languages, Java strings are objects. When you compare two strings using ==, it compares the memory addresses where those objects reside, not the actual string values.

To compare the actual values of strings, you should use the String.equals method:

if ("231".equals(parts[0])) {
    // This comparison will evaluate to true
}

This method checks the content of the strings, not their object references.

Remember, for all objects in Java, the == operator checks reference equality, while the equals method compares the actual object values. It's important to use equals when checking for equality of objects, as == can lead to incorrect conclusions when comparing object references.

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