Introduction to Java Collections class

2024-07-12

Java'sjava.util.CollectionsClasses copiam methodorum staticorum praebent ad collectiones manipulandas vel reddendas (ut sunt tabulae, tabulae, tabulae).Collections Classis est utilitas classis disposita ad algorithmos et operationes in collectionibus opportunas praebendas.par haec estCollectionsIntroductio in classes et methodos communium eorum.

Communium methodorum Summa

sort：sort(List<T> list)、sort(List<T> list, Comparator<? super T> c)
Find：binarySearch(List<? extends Comparable<? super T>> list, T key)、binarySearch(List<? extends T> list, T key, Comparator<? super T> c)
vicissim：reverse(List<?> list)
rotate：rotate(List<?> list, int distance)
impletio：fill(List<? super T> list, T obj)
effingo：copy(List<? super T> dest, List<? extends T> src)
min et max *：min(Collection<? extends T> coll)、max(Collection<? extends T> coll)
sync collectione：synchronizedList(List<T> list)、synchronizedSet(Set<T> s)、synchronizedMap(Map<K, V> m)
immutabilis collectio：unmodifiableList(List<? extends T> list)、unmodifiableSet(Set<? extends T> s)、unmodifiableMap(Map<? extends K, ? extends V> m)

sort

sort(List<T> list): Indicem in ascendendo dispone, elementa in indice deducendi suntComparableinstrumenti.


List<Integer> numbers = Arrays.asList(5, 3, 1, 4, 2);
Collections.sort(numbers); // 排序后，numbers为 [1, 2, 3, 4, 5]

sort(List<T> list, Comparator<? super T> c): Perpensis elenchus secundum certa comparator.


List<String> names = Arrays.asList("Charlie", "Alice", "Bob");
 
// 根据字符串长度排序
Collections.sort(names, (s1, s2) -> s1.length() - s2.length());

Note: Collections.sort (nomina, (s1, s2) -> s1.length() - s2.length()) (s1, s2) -> s1.length() - s2.length() Haec est elocutio Lambda ad efficiendum comparandi modum comparatoris instrumenti.

Find

binarySearch(List<? extends Comparable<? super T>> list, T key) : Percontatione binaria utere ut elementum in indice invenias et indicem reddas. Elenchus fringilla sit amet.


List<Integer> sortedNumbers = Arrays.asList(1, 2, 3, 4, 5);
int index = Collections.binarySearch(sortedNumbers, 3); // 返回索引 2

binarySearch(List<? extends T> list, T key, Comparator<? super T> c): Percontatione binaria utere ad elementum inveniendum in elencho comparati determinati.


List<String> sortedNames = Arrays.asList("Alice", "Bob", "Charlie");
int index = Collections.binarySearch(sortedNames, "Bob", String::compareTo); // 返回索引 1

maximum et minimum values

max(Collection<? extends T> coll): redit elementum maximum in collectione.


List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
int max = Collections.max(numbers); // 返回 5

min(Collection<? extends T> coll): redit elementum minimum in statuto.

int min = Collections.min(numbers); // 返回 1

Inverso ordine

reverse(List<?> list): elementa in album converte.


List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
Collections.reverse(numbers); // 反转后，numbers为 [5, 4, 3, 2, 1]

randomization

shuffle(List<?> list): passim miscere album.

Collections.shuffle(numbers); // numbers的元素顺序将被随机打乱

impletio

fill(List<? super T> list, T obj): Restitue omnia elementa in elencho cum elemento determinato.


List<String> list = new ArrayList<>(Arrays.asList("a", "b", "c"));
Collections.fill(list, "z"); // list 现在是 ["z", "z", "z"]

effingo

copy(List<? super T> dest, List<? extends T> src): Exemplar omnia elementa in indice fonti ad scopum indicem.


List<String> dest = Arrays.asList(new String[3]);
List<String> src = Arrays.asList("a", "b", "c");
Collections.copy(dest, src); // dest 现在是 ["a", "b", "c"]

immutabilis collectio

unmodifiableList(List<? extends T> list): immodificabile reddit visum.


List<String> list = Arrays.asList("a", "b", "c");
List<String> unmodifiableList = Collections.unmodifiableList(list);
// unmodifiableList.add("d"); // 会抛出 UnsupportedOperationException

sync collectione

synchronizedList(List<T> list): incolumem redit indicem.


List<String> list = new ArrayList<>();
List<String> syncList = Collections.synchronizedList(list);

Exemplum summary

Hic est exemplum comprehensivum ostendensCollectionsCommunia quaedam genera generum:


import java.util.*;
 
public class CollectionsExample {
    public static void main(String[] args) {
        List<Integer> numbers = new ArrayList<>(Arrays.asList(5, 3, 1, 4, 2));
 
        // 排序
        Collections.sort(numbers);
        System.out.println("排序后: " + numbers);
 
        // 反转
        Collections.reverse(numbers);
        System.out.println("反转后: " + numbers);
 
        // 随机打乱
        Collections.shuffle(numbers);
        System.out.println("随机打乱后: " + numbers);
 
        // 查找最大和最小值
        int max = Collections.max(numbers);
        int min = Collections.min(numbers);
        System.out.println("最大值: " + max + ", 最小值: " + min);
 
        // 二分搜索
        Collections.sort(numbers);
        int index = Collections.binarySearch(numbers, 3);
        System.out.println("元素 3 的索引: " + index);
 
        // 同步集合
        List<String> syncList = Collections.synchronizedList(new ArrayList<>());
        syncList.add("a");
        syncList.add("b");
        System.out.println("同步集合: " + syncList);
    }
}

ab usuraCollectionsHae methodi a classibus praevisae facile varias operationes in collectione praestare possunt, ad codicis promptitudinem et conservationem emendandam.

refer ad:

Collectiones (Java SE 17 & JDK 17)

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