| .count() 计数 | .map(x → x+3).collect(Collectors.toList()) 元素增值 .map(String::toUpperCase) 转变大写 | | --- | --- | | .collect(Collectors.toList()) .toSet .toMap | | | | |

import java.util.*;

public class StringLengthSortExample {
    public static void main(String[] args) {
        List<String> words = Arrays.asList("apple", "pear", "banana", "cherry", "fig");

        // 按字符串长度排序（从小到大）
        List<String> sortedWords = words.stream()
                .sorted(Comparator.comparingInt(String::length))
                .collect(Collectors.toList());

        System.out.println(sortedWords); // 输出：[fig, pear, apple, banana, cherry]

        // 找到最大值
        Optional<Integer> maxNumber = numbers.stream().max(Comparator.naturalOrder());
        maxNumber.ifPresent(max -> System.out.println("最大值: " + max)); // 输出：最大值: 9
				
				//计算元素个数
				long count = numbers.stream() // 将列表转换为流
                             .filter(n -> n > 6) // 筛选出大于6的元素
                             .count(); // 计算经过筛选的元素数量
				System.out.println(count);

				//转换大写、元素全+3
				String[] strArr = { "abcd", "bcdd", "defde", "fTr" };
				List<String> strList = Arrays.stream(strArr).map(String::toUpperCase).collect(Collectors.toList());

				List<Integer> intList = Arrays.asList(1, 3, 5, 7, 9, 11);
				List<Integer> intListNew = intList.stream().map(x -> x + 3).collect(Collectors.toList());

				System.out.println("每个元素大写：" + strList);
				System.out.println("每个元素+3：" + intListNew);
				
				//求和求积
				Optional<Integer> sum = list.stream().reduce((x, y) -> x + y);
				Optional<Integer> product = list.stream().reduce((x, y) -> x * y);
				int sum = a.stream().reduce((x, y) -> x + y).orElse(0);
    	System.out.println(sum);

				//去重
					List<String> newList = Stream.concat(stream1, stream2).distinct().collect(Collectors.toList());
					
				//二维数组打印   				
 				Arrays.stream(dis)
              .map(row -> Arrays.toString(row))
              .forEach(System.out::println);
}
}

Stream流式操作