java list stream group sort

To sort and group a List using Stream in Java, you can follow these steps:

Create a List of objects.

List<YourObject> list = new ArrayList<>();
list.add(new YourObject("Object1", 10));
list.add(new YourObject("Object2", 20));
list.add(new YourObject("Object3", 10));
list.add(new YourObject("Object4", 20));

Use the stream() method to convert the List into a Stream.

Stream<YourObject> stream = list.stream();

Use the collect() method to group and sort the objects in the Stream.

Map<Integer, List<YourObject>> groupedAndSortedMap = stream
        .collect(Collectors.groupingBy(YourObject::getSomeProperty, TreeMap::new, Collectors.toList()));

In the groupingBy() method, you specify the property by which you want to group the objects (in this example, getSomeProperty()), and it creates a Map where the key is the property value and the value is a List of objects with that property value. The TreeMap::new parameter is used to create a sorted map based on the keys.

Now, you can iterate over the grouped and sorted map to access the objects.

for (Map.Entry<Integer, List<YourObject>> entry : groupedAndSortedMap.entrySet()) {
    int key = entry.getKey();
    List<YourObject> objects = entry.getValue();

    System.out.println("Key: " + key);
    for (YourObject object : objects) {
        System.out.println(object.getName());
    }
}

This will print the grouped and sorted objects based on the specified property.

Note: Replace YourObject with the actual class name of your objects, and getSomeProperty() with the actual method name that returns the property value for grouping and sorting