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 " + isNullEmpty(str1)); // check if str2 is null...
/*Java Program to check if a string is empty or null*/ public class Main { public static void main(String[] args) { String str1 = "Study Tonight"; String str2 = null; System.out.println("Is string: " + str1 +" empty or null? " + isEmptyOrNull(str1)); System.out.println(...
Check if String is Null or Empty 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 Convert Char to String in Java ...
if (str3 == null || str3.length() == 0) { System.out.println("str3 is null or empty."); } else { System.out.println("str3 is not null or empty."); } } } The code example demonstrates the if-else method for checking if a string is null or empty in Java. It utilizes ...
In application programming, it is advisable to check both if list is not null and then not empty. If list is not initialized, we may getNullPointerExceptionin runtime. 2. UsingArrayList.size() Another way to check if the arraylist contains any element or not, we can check the size of ...
Check if a string is null or empty in XSLT 多条件查询 string.Format("/root/deviceList//item/guid[{0}]", strBuilder.ToString()) "/root/deviceList//item/guid[text()=\"h\" or text()=\"a\" or text()=\"c\"]"谓词嵌套var nodes = xmlDoc.SelectNodes(string.Format("/root/device...
空指针(Null Pointer Exception,NPE)是Java中最常见不过的异常了。其原因虽然显而易见,但是开发人员往往会忽略,或未能及时采取措施。本文将和您详细讨论空指针问题的根源,以及对应的解决方法。 空引用破坏了Java类型安全性 Java通过提供编译类型的安全性(Compile Type Safety),来保证开发人员不会错配不同的变量类型。
String nullString =null; String emptyString =""; String blankString =" "; In this tutorial, we'll look athow to check if a String is Null, Empty or Blank in Java. Using the Length of the String As mentioned before, a string is empty if its length is equal to zero. We will be...
if(obj!=null){// 执行操作} 1. 2. 3. 2. 使用安全调用运算符 Java 8及以上版本引入了安全调用运算符(?.),它可以在调用方法或访问属性之前检查对象是否为null。如果对象为null,运算符会直接返回null,而不会抛出空指针异常。 Stringstr=null;intlength=str?.length(); ...
Java 7 introduced the newObjectsAPI. This API has severalstaticutility methods that take away a lot of redundant code. Let’s look at one such method,requireNonNull(): Now let’s test theaccept()method: So, ifnullis passed as an argument,accept()throws aNullPointerException. ...