Example 1: Check if String is Empty or Null class Main { public static void main(String[] args) { // create null, empty, and regular strings String str1 = null; String str2 = ""; String str3 = " "; // check if str1 is null or empty System.out.println("str1 is " + is...
whenInputIsNull_thenReturnsDefaultMessage :此测试检查输入为null时方法的行为。它断言该方法返回预期的默认消息。 whenInputIsNotNull_thenProcessesInput:此测试验证该方法是否正确处理非空输入字符串。它断言该方法返回预期的连接字符串。 这些测试有效地记录了processString()方法如何处理null和非 null 情况,提供了使用...
int end) {this.begin = begin;this.end = end;}@Overridepublic String toString() {return "{" + begin + ", " + end + '}';}@Overrideprotected Integer compute() {if (begin == end){log.debug("join():{}",begin);return begin;}if (end -...
public void given3Streams_whenPrepending_thenResultStreamContainsAllElements() { Stream<String> seq = Stream.of("foo", "bar"); Stream<String> openingBracketSeq = Stream.of("["); Stream<String> closingBracketSeq = Stream.of("]"); Stream<String> resultingStream = Seq.ofType(seq, String.cla...
public String getCarInsuranceName(Person person) { if (person == null) { return "Unknown"; } Car car = person.getCar(); if (car == null) { return "Unknown"; } Insurance insurance = car.getInsurance(); if (insurance == null) { ...
Check if a String is Null, Empty or Blank in Java Java: Check if String is Numeric How to Convert String to int in Java Reverse a String in Java Convert int to String in Java How to Split a String in Java: Different Examples
if (username == null || username.trim().isEmpty()) { throw new IllegalArgumentException("用户名不能为空"); } if (!Pattern.matches(EMAIL_REGEX, email)) { throw new IllegalArgumentException("邮箱格式错误"); } // 重复代码多 正解(标准化校验): ...
通过注释可以知道:如果值为null返回false,不为null返回true。 实例如下: if (name.isPresent()) { System.out.println(name.get());//输出javaHuang } emptyValue.isPresent()==false get 源码: /** * If a value is present in this {@code Optional}, returns the value, * otherwise throws {@code...
Stringname=null;if(insurance !=null){ name = insurance.getName(); } 为了支持这种模式,Optional 提供了一个 map 方法。它的工作方式如下: Optional<Insurance> optionalInsurance = Optional.ofNullable(insurance); Optional<String> name = optionalInsurance.map(Insurance::getName); ...
问If ( null & null) Java函数式编程EN在Java 8之前，我习惯了用这种方式写代码这将给出第一个非...