For Loop vs. For-Each Loop: Which is Faster for Iterating in Java?

Performance Comparison of for loop vs. for-each loop

Optimizing code performance is crucial in programming. When iterating through a list of objects, developers commonly face a dilemma between using a traditional for loop and a for-each loop.

Consider the following two loops:

for (Object o : objectArrayList) {
    o.DoSomething();
}

for (int i=0; i<objectArrayList.size(); i++) {
    objectArrayList.get(i).DoSomething();
}

Which loop performs faster?

According to Item 46 in Effective Java by Joshua Bloch, there is no discernible performance difference between the two loops. In fact, the for-each loop may slightly outperform the for loop in specific scenarios.

The for-each loop eliminates boilerplate code and potential errors by concealing the iterator or index variable. The syntax, which reads as "for each element e in elements," simplifies code readability.

Furthermore, Bloch notes that the for-each loop computes the limit of the array index only once, which eliminates a potential performance bottleneck present in manually written for loops.

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