background
In development, sometimes I need to split a list collection into multiple small list collections for processing, for example: using multiple threads to process the split small collection asynchronously to improve efficiency. The following will split the sample collection:
The first type: equal splitting
private List<List<String>> partition(List<String> originalList, int size) {
List<List<String>> partition = new ArrayList<>();
int totalSize = ();
// Calculate the size of each set and round it up int groupSize = (totalSize / size) + 1;
for (int i = 0; i < size; i++) {
int start = i * groupSize;
// Prevent array from crossing boundaries int end = (start + groupSize, totalSize);
(new ArrayList<>((start, end)));
}
return partition;
}
The second type: specify the number to split
ImportgoogleofguavaToolkit
<dependency>
<groupId></groupId>
<artifactId>guava</artifactId>
</dependency>
private List<List<String>> partition(List<String> originalList) {
// Specify the number -> Split every 1000 into a small collection List<List<String>> partition = (originalList, 1000);
return partition;
}
The third type: split according to the conditions
private List<List<Integer>> partition() {
List<Integer> numbers = (10, 20, 30, 40, 50, 60, 70, 80, 90);
List<List<Integer>> groups = new ArrayList<>();
(new ArrayList<>()); // Less than or equal to 50 (new ArrayList<>()); // Greater than 50
for (Integer number : numbers) {
if (number <= 50) {
(0).add(number);
} else {
(1).add(number);
}
}
return groups;
}Summarize
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