importjava.util.Objects;publicbooleanisNullOrEmpty(Stringstr){returnObjects.isNull(str);} 1. 2. 3. 4. 5. 状态图 Check|str==null|Null|str.isEmpty()|EmptyValid 序列图 StringUtilClientStringUtilClientalt[str is null][str is empty]isNullOrEmpty(str)Check if str is null or emptyreturn trueret...
下面是一个完整的代码示例,展示了如何使用上述步骤来判断集合是否为空或者为 null: publicbooleanisCollectionEmptyOrNull(Collection<?>collection){if(collection==null){// 集合为空returntrue;}if(collection.isEmpty()){// 集合为空returntrue;}else{// 集合不为空returnfalse;}} 1. 2. 3. 4. 5. 6. ...
/** * 检查字符串是否为null或空 * *@paraminput 待检查的字符串 */ publicstaticvoidcheckString(String input){ if(input ==null|| input.isEmpty) { System.out.println("字符串是null或空。"); }else{ System.out.println("字符串不是null也不是空。其值为: "+ input); } } /** * 安全地...
Using the isBlank() method (available from Java 11 onwards): The isBlank() method is a convenient way to check if a string is empty or contains only whitespace characters. It returns true if the string is empty or consists solely of whitespace, and false otherwise. String str1 = ""; ...
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...
当在集合中进行 null 判断时,可以使用以下方式: List<String>list=newArrayList<>();if(!list.isEmpty()&&list.get(0)!=null){StringfirstElement=list.get(0);// 对 firstElement 进行操作} PHP 复制 在这个例子中,首先使用!list.isEmpty()检查集合是否为空,然后再使用list.get(0)!= null检查集合中的...
findMax(null); } privatestaticvoid findMax(int[] arr){ int max = arr[0]; //check other elements in loop } 这会在第6行导致 NullPointerException。因此,访问空 对象的任何字段,方法或索引会导致 NullPointerException,如上面的示例所示。避免 NullPointerException的 常见方法是检查 null: ...
* @param cs the CharSequence to check, may be null * @return {@code true} if the CharSequence is empty or null * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence) */ publicstaticbooleanisEmpty(finalCharSequence cs) { ...
publicvoidtestGuava(Object arg){Object checked=Preconditions.checkNotNull(arg,"%s must not be null","arg");checked.toString();} 我们还可以使用Lombok来生成空值检测代码,并抛出带有提示信息的空指针异常: 代码语言:javascript 复制 publicvoidtestLombok(@NonNull Object arg){arg.toString();} ...
Returns true if this set has no elements. C# 複製 public bool IsEmpty { [Android.Runtime.Register("isEmpty", "()Z", "GetIsEmptyHandler:Java.Util.ISetInvoker, Mono.Android, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null")] get; } Property Value Boolean Implements IsEmpty ...