冒泡排序

public class BubbleSort {public static void main(String[] args) {int[] numbers = {64, 34, 25, 12, 22, 11, 90};bubbleSort(numbers);for (int number : numbers) {System.out.print(number + " ");}}public static void bubbleSort(int[] arr) {for (int i = 0; i < arr.length - 1; i++) {for (int j = 0; j < arr.length - 1 - i; j++) {if (arr[j] > arr[j + 1]) {int temp = arr[j];arr[j] = arr[j + 1];arr[j + 1] = temp;}}}}
}

二分算法

 public static int binarySearch(int[] arr, int target) {int left = 0, right = arr.length - 1;while (left <= right) {int mid = left + (right - left) / 2; //拿到二分下表if (arr[mid] == target) {return mid;}if (arr[mid] < target) {left = mid + 1;} else {right = mid - 1;}}return -1;}

大文件拆分合并

/*** Author: 徐寿春* Date:    2024/11/15 10:33* <p>* 名称*/
public class FileSplitter {public static void splitFile(File inputFile, int chunkSize) throws Exception {@Cleanup FileInputStream fis = new FileInputStream(inputFile);@Cleanup BufferedInputStream bis = new BufferedInputStream(fis);byte[] buffer = new byte[chunkSize];String fileName = inputFile.getName();int tmp;while ((tmp = bis.read()) != -1) {String filePartName = String.format("%s.%03d", fileName, tmp);//创建小文件File newFile = new File(inputFile.getParent(), filePartName);@Cleanup FileOutputStream out = new FileOutputStream(newFile);out.write(buffer, 0, tmp); // tmp是实际读取的字节数}}public static void mergeFiles(File[] inputFiles, File outputFile) throws Exception {@Cleanup FileOutputStream fos = new FileOutputStream(outputFile);@Cleanup BufferedOutputStream mergingStream = new BufferedOutputStream(fos);for (File file : inputFiles) {@Cleanup FileInputStream fis = new FileInputStream(file);@Cleanup BufferedInputStream mingStream = new BufferedInputStream(fis);byte[] buffer = new byte[1024];int bytesRead;while ((bytesRead = mingStream.read(buffer)) != -1) {mergingStream.write(buffer, 0, bytesRead);}}}public static void main(String[] args) throws Exception {File inputFile = new File("path/to/large/file.txt");int chunkSize = 1024 * 1024 * 10; // 10MBsplitFile(inputFile, chunkSize);File outputFile = new File("path/to/output/file.txt");File[] inputFiles = new File[]{new File("path/to/large/file.txt.001"),new File("path/to/large/file.txt.002"),// ...};mergeFiles(inputFiles, outputFile);}
}

统计并返回出现次数最多的单词及其出现次数

给定一个包含多行文本的字符串（每行以换行符\n分隔），要求编写一个Java方法来实现以下功能：统计并返回字符串中所有单词的总数（假设单词由空格分隔，且单词之间可以有多个空格，单词只有英文字符）。统计并返回出现次数最多的单词及其出现次数（如果有多个单词出现次数相同且最多，则返回其中任意一个）。统计并返回字符串中所有不同单词的数量。

例子：String text = “Hello world. This is a test.\n Another test, with Hello again.”;

/*** Author: 徐寿春* Date:    2024/11/15 11:09* <p>* 名称*/
public class WordStatistics {public static void wordStatistics(String str) {Map<String, Long> collect = Arrays.stream(str.split("")).filter(i ->!Objects.equals(i, ",")&& !Objects.equals(i, ".")&& Strings.isNotBlank(i)).collect(Collectors.groupingBy(String::toLowerCase, Collectors.counting()));collect.entrySet().stream().max(Map.Entry.comparingByValue()).ifPresent(i -> {System.out.println("出现最多的单词 = " + i.getKey());System.out.println("出现最多的数量 = " + i.getValue());});System.out.println("共出现的数量 = " + collect.entrySet().size());}public static void main(String[] args) {String text = "Hello world. This is a test.\n Another test, with Hello again.";wordStatistics(text);}
}