AI检测代码解析 publicclassPerson{privateStringname;publicStringgetName(){returnname;}}publicclassNullPointerExceptionExample{publicstaticvoidmain(String[]args){Personperson=null;if(person!=null){Stringname=person.getName();System.out.println("姓名:"+name);}else{System.out.println("人员对象为空!");...
而聪明的读者,可能一眼就看到了初始化是null,然后getGender()的入参是int,这里就是“包装类型”向“基本类型”转换的“坑”。 java.lang.NullPointerExceptionat net.jhelp.demo.ProgrammerBTest.getGender2(ProgrammerBTest.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethod) at sun.reflect....
So, from a compiler perspective, there is nothing wrong. Null belongs to String type and Java will not even print a warning. Actually, you can compile even the next code: But, once we run this program, it will fail with NullPointerException: NullPointerException Definition NullPointerException...
What is Null Pointer Exception? In object-oriented programming, when a class is instantiated, its object is stored in computer memory. To refer to this object and to use it in a program requires a reference variable of the type of the class that has an object has to be instantiated. This...
发生NullPointerException的情况: 调用null 对象的实例方法。 访问或修改 null 对象的字段。 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:...
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...
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。
But When I run this programme it shows java.lang.NullPointerException. I don't know why. How can avoid this error? Thanks In Advance.My Code: import java.io.OutputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.StringTokenizer; ...
打开很古老的DbVis的6.5.1版本,准备工作时,发现竟然报错,打不开,窗口显示下面错误 java.lang.NullPointerException, 空指针错误,使用Stack Trace得到具体错误信息如下 java.lang.NullPointerException at se.pureit.swing.xmlactions.keys.impl.MultiInputMapDelegate.get(Z:137) ...
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) {