This page contains an archived post to the Java Answers Forum made prior to February 25, 2002.
If you wish to participate in discussions, please visit the new
Artima Forums.
Message:
String
Posted by sanjay singh on July 19, 2000 at 11:18 AM
I want to know the explanation for a situation i am facing while running a small java program . I am trying to run a small java program using String and getting a result and I am not able to convice myself Can you please take a little pain in answering my question . Let me write down my java proggram . It is 15 line program . I am going to metion line number in my question . My java source Code : 1 public class test9 { 2 String s1 = null ; 3 String s2 = " "; 4 public void amethod() 5 { 6 if (s1.equals(s2)) 7 System.out.println("equals"); 8 } 9 public static void main(String args[]) 10 { 11 test9 a = new test9(); 12 a.amethod(); 13 } 15 } My question: Here is the situation For the above code I am getting a NullPointerException as follow while running it. C:\jdk1.2.1\bin>java test9 Exception in thread "main" java.lang.NullPointerException at test9.amethod(test9.java:9) at test9.main(test9.java:22) But it does not throw NullPointerException when String S1 = " " is mentioned at line# 2 and String S2 = null is mentioned at line# 3; Why is it so ? The second scenario should also give NullPointerException. Does the left hand side of equals() method have to be initialized ? for more detail reference ..I do not get NullPointerException when I change my java program as follow . Modified program : Which runs fine . does not throw NullPointerException why ? public class test9 { String s1 = " "; String s2 = null; public void amethod() { if (s1.equals(s2)) System.out.println("equals"); }
public static void main(String args[]) { test9 a = new test9(); a.amethod(); } } If my question is not clear Please send me a mail asking for detail.
Replies:
- RE:String Kishori Sharan July 19, 2000 at 5:20 PM
(0)
|