使用Map()进行R类型转换

# 定义一个字符串列表
str_list = ["1", "2", "3", "4", "5"]

# 使用 map() 将字符串列表转换为整数列表
int_list = list(map(int, str_list))

print(int_list)  # 输出: [1, 2, 3, 4, 5]

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class MapExample {
    public static void main(String[] args) {
        // 定义一个字符串列表
        List<String> strList = Arrays.asList("1", "2", "3", "4", "5");

        // 使用 map() 将字符串列表转换为整数列表
        List<Integer> intList = strList.stream()
                                       .map(Integer::parseInt)
                                       .collect(Collectors.toList());

        System.out.println(intList);  // 输出: [1, 2, 3, 4, 5]
    }
}

# 错误的示例：输入包含非数字字符串
str_list = ["1", "2", "three", "4", "5"]

try:
    int_list = list(map(int, str_list))
except ValueError as e:
    print(f"Error: {e}")  # 输出: Error: invalid literal for int() with base 10: 'three'

# 使用 filter() 过滤掉非数字字符串
str_list = ["1", "2", "three", "4", "5"]
int_list = list(map(int, filter(lambda x: x.isdigit(), str_list)))
print(int_list)  # 输出: [1, 2, 4, 5]

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class MapExample {
    public static void main(String[] args) {
        // 错误的示例：输入包含非数字字符串
        List<String> strList = Arrays.asList("1", "2", "three", "4", "5");

        List<Integer> intList = strList.stream()
                                       .filter(s -> s.matches("\\d+"))
                                       .map(Integer::parseInt)
                                       .collect(Collectors.toList());

        System.out.println(intList);  // 输出: [1, 2, 4, 5]
    }
}