It doesn't take much Java development experience to learn firsthand what the NullPointerException is about. In fact, one person has highlighted dealing with this as the number one mistake Java ...

"java.lang.NullPointerException: Cannot invoke method getFile () on null object" during build test #33 Closed g0blin79 opened on May 26, 2019 ...

Java is not a particularly beginner-friendly language and it is rife with rigid rules and structures that can be tough to wrap your head around. Then there’s the NullPointerException.

mybatis version : 3.3.0 mybatis-spring version: 1.2.2 1st Scenes ： Caused by: java.lang.NullPointerException at org.apache.ibatis.reflection.property ...

***Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener (android.view.View$OnClickListener)' on a null object reference ...