publicclassNullPointerExceptionExample{publicstaticvoidmain(String[]args){Stringstr=null;intlength=str.length();// 这里会抛出空指针异常System.out.println("字符串长度:"+length);}} 1. 2. 3. 4. 5. 6. 7. 在上面的代码中,我们创建了一个字
The above program throws the following NullPointerException stack trace. Exceptionin thread"main"java.lang.NullPointerExceptionatTemp.main(Temp.java:9) Copy NullPointerException is being thrown in statementint i = t.x;because “t” is null here. 3. Java NullPointerException when null is passed ...
如果一个数组为null,试图用属性length获得其长度时。 如果一个数组为null,试图访问或修改其中某个元素时。 在需要抛出一个异常对象,而该对象为 null 时。 首先,我们先找到Java.lang.NullPointerException这个类,内容很简单: package java.lang; /** * Thrown when a program tries to access a field or method...
But, once we run this program, it will fail with NullPointerException: NullPointerException Definition NullPointerException is a Runtime exception that is thrown when Java tries to call any method on a real object but in runtime this object references to the Null Reference. More details about ...
Exception in thread "main" java.lang.NullPointerException 1. 您收到此错误的原因是因为我们正在尝试对str1执行length()操作,str1是null。 一个简单的解决方法是对str1添加空检查,如下所示: private static void simpleNullCheck(String str1) {
空指针错误 java.lang.NullPointerException 浅谈 使用基本的JAVA数据类型,变量的值要么已经是默认值,如果没有对其正常赋值,程序便不能通过编译,因此使用基本的JAVA数据类型(double,float,boolean,char,int,long)一般不会引起空指针异常。由此可见,空指针异常主要跟与对象的操作相关。
the call togetUSB()will try to return the USB port of a null reference, which will result in aNullPointerExceptionat runtime and stop your program from running further. Imagine if your program was running on a customer's machine; what would your customer say if the program suddenly failed...
System.out.print("NullPointerException Caught"); } } } 输出: 捕获空指针异常 我们可以通过对文字而不是对象调用 equals 来避免 NullPointerException。 // A Java program to demonstrate that we can avoid// NullPointerExceptionimport java.io.*;classGFG{publicstaticvoidmain(String[] args){// Initiali...
23.“NullPointerException” 当程序尝试使用没有赋值的对象引用时,就会出现“NullPointerException”异常。 // A Java program to demonstrate thatinvoking a method // on null causes NullPointerException import java.io.*; classGFG { publicstaticvoidmain(String[] args) ...
问java中的java.lang.NullPointerexceptionEN1、在window操作系统上，使用eclipse开发工具从hdfs分布式文件...