JDK 1.4 the NullPointerException - Java Tutorials

NullPointerException In Java

NullPointerException occurs when you perform an operation on a object or calling a method on the object.  The only way to solve Null Pointer Exception is to avoid executing operation on a object or calling a method on the object.

Example

Given below example will give you a clear idea :

package simpleCoreJava;

public class JavaNullpointerexception {
public static void main(String args[]) {
String string[] = new String[2];
System.out.println(string[1].charAt(1));

}
}

Code Description

In the above class we have declared a String array which has size 2. But we haven't initialize the array therefore at position 1 there is nothing. So When we call charAt() function, the above code throw NullPointerException.

Output

Correction of the above code

You can Correct the above code as follows :

package simpleCoreJava;

public class JavaNullpointerexception {
public static void main(String args[]) {
String string[] = new String[3];
string[0] = "ankit";
string[1] = "ankit";
string[2] = "ankit";
System.out.println(string[1].charAt(1));

}
}

The Output of the above code will be :