Java解决NullReferenceException异常的方法小结

package cn.juwatech.nullpointerexamples;

public class NullReferenceExample {

    public static void main(String[] args) {
        String str = null;
        int length = str.length(); // 这里会抛出NullPointerException
        System.out.println("Length of str: " + length);
    }
}

String str = null;
if (str != null) {
    int length = str.length(); // 执行操作前先进行null检查
    System.out.println("Length of str: " + length);
} else {
    System.out.println("str is null, cannot get length.");
}

import java.util.Optional;

public class OptionalExample {

    public static void main(String[] args) {
        String str = null;
        Optional<String> optionalStr = Optional.ofNullable(str);
        if (optionalStr.isPresent()) {
            int length = optionalStr.get().length();
            System.out.println("Length of str: " + length);
        } else {
            System.out.println("str is null, cannot get length.");
        }
    }
}

import java.util.Objects;

public class RequireNonNullExample {

    public void processString(String str) {
        Objects.requireNonNull(str, "str must not be null");
        int length = str.length(); // 这里如果str为null，会立即抛出NullPointerException
        System.out.println("Length of str: " + length);
    }

    public static void main(String[] args) {
        RequireNonNullExample example = new RequireNonNullExample();
        example.processString(null); // 抛出NullPointerException
    }
}

try {
    // 可能抛出空指针异常的代码
} catch (NullPointerException e) {
    logger.error("Caught NullPointerException: " + e.getMessage(), e);
    // 其他异常处理逻辑
}