# Replace For-Loop with Stream::sum

# Properties

Property Value
Rule ID EnhancedForLoopToStreamSum
First seen in jSparrow version 2.2.0
Minimum Java version 8
Remediation cost 10 min

# Description

Transforms enhanced for-loops which are only used for summing up the elements of a collection into a stream and uses the sum operation to compute the result.

# Benefits

Applying this rule yields no major performance benefits. One could argue that readability is somewhat improved, at least if one is familiar with lambdas.

# Code Changes

# List of integers

Pre

List<Integer> numbers = generateIntList(input);
int sum = 0;
for(int n : numbers) {
    sum += n;
}

Post

List<Integer> numbers = generateIntList(input);
int sum = numbers.stream().mapToInt(Integer::intValue).sum();

# List of doubles

Pre

List<Double> numbers = generateDoubleList(input);
double sum = 0;
for(double n : numbers) {
    sum += n;
}

Post

List<Double> numbers = generateDoubleList(input);
double sum = numbers.stream().mapToDouble(Double::doubleValue).sum();

Automatic Application of This Rule

The automatic application of this rule is supported in the following jSparrow version:

# Tags

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