How does the Java collection framework improve code writing efficiency?

The Java collection framework improves code efficiency by providing tools for storing and managing data. It contains multiple collection types (lists, sets, maps), as well as utility methods for traversing, searching, sorting, and deleting. In practical applications, the collection framework simplifies data processing, such as using forEach() to traverse lists, using contains() to search for elements, and using stream().filter() to filter data.

Java Collection Framework: Improve code writing efficiency

Java Collection Framework is a set of interfaces and classes used for storage and management data. It provides developers with tools to process data efficiently, thereby increasing the efficiency of their code.

Collection Types

The collection framework contains multiple collection types, each with its specific usage:

• List: An ordered collection of elements, allowing duplicate elements.
• Set: Unordered, a set that does not contain duplicate elements.
• Map: A collection of key-value pairs, where the key is used to uniquely identify the value.

Practical methods

The collection framework provides a wealth of practical methods to simplify data processing:

• Traversal : Use forEach(), iterator() or stream() to traverse the collection.
• Search: Search for elements using contains(), indexOf() or stream().filter() .
• Sort: Sort a collection using sort(), Comparator or stream().sorted() .
• Remove: Use remove(), clear() or stream().filter(Predicate.negate()) Remove elements from the collection.

Practical case

The following code example demonstrates using the collection framework to improve code efficiency:

// 创建一个学生姓名列表
List<String> students = new ArrayList<>();

// 添加学生姓名
students.add("Alice");
students.add("Bob");
students.add("Carol");

// 使用 forEach() 遍历列表
System.out.println("Students:");
students.forEach(System.out::println);

// 使用 contains() 搜索学生
if (students.contains("Bob")) {
    System.out.println("Bob is in the list.");
}

// 使用 stream().filter() 筛选成绩大于 80 分的学生
Map<String, Integer> scores = new HashMap<>();
scores.put("Alice", 90);
scores.put("Bob", 85);
scores.put("Carol", 75);

System.out.println("Students with scores above 80:");
scores.entrySet().stream()
    .filter(entry -> entry.getValue() > 80)
    .map(Map.Entry::getKey)
    .forEach(System.out::println);

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