Problem in loading a Properties File

Question

Following is my program which is actually reading a Properties file from a specific location and saving it latter. The program is able to save the Properties file but gives NullPointerException while reading it back.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import com.server.config.ConfigurationException;
import com.server.config.SimpleNetworkConfigurationManager;
public class Test {
     private static final Properties DEFAULT_CONFIGURATION;
     private static final String CONFIGURATION_FILE = "config/server_config.cfg";
     protected Properties m_config;
     static {
          DEFAULT_CONFIGURATION = new Properties();
          DEFAULT_CONFIGURATION.setProperty("ServerName", "Utility Server");
          DEFAULT_CONFIGURATION.setProperty("Host", "localhost");
          DEFAULT_CONFIGURATION.setProperty("Port", "1100");
     public Test(){
          try {
               loadConfiguration();
          } catch (ConfigurationException e) {
               //TODO: Log error message
               System.out.println("Could not load Configuration; Reason: "+e.getMessage());
               this.m_config = new Properties();
               this.m_config.putAll(DEFAULT_CONFIGURATION);
     public Map getAllConfigurationParameters() {
          return m_config;
     public Set getConfigurationKeys() {
          return m_config.keySet();
     public Object getValue(String configurationParameter) {
          return m_config.getProperty(configurationParameter);
     public void loadConfiguration() throws ConfigurationException{
          try {
               this.m_config.load(new FileInputStream(CONFIGURATION_FILE));
          } catch (FileNotFoundException e) {
               throw new ConfigurationException(e);
          } catch (IOException e) {
               throw new ConfigurationException(e);
     public void saveConfiguration() throws ConfigurationException {
          FileOutputStream fos = null;
          try {
               File file = new File(CONFIGURATION_FILE);
               file.createNewFile();
               fos = new FileOutputStream(file);
               this.m_config.store(fos,"Utility Server Configuration");
          } catch (FileNotFoundException e) {
               throw new ConfigurationException(e);
          } catch (IOException e) {
               throw new ConfigurationException(e);
          }finally{
               if (fos!=null){
                    try {
                         fos.close();
                    } catch (IOException e) {
                         //ignore
                    fos = null;
     public void setConfigurationParameters(Properties configurationParameters) {
          this.m_config = new Properties(configurationParameters);
     public String setConfigurationParameter(String param, String value) {
          return (String)this.m_config.setProperty(param, value);
     public static void main(String[] args) {
          Test configManager = new Test();
          try {
               configManager.saveConfiguration();
          } catch (ConfigurationException e) {
               e.printStackTrace();
}The Exception is as follows:
Exception in thread "main" java.lang.NullPointerException
     at Test.loadConfiguration(Test.java:52)
     at Test.<init>(Test.java:29)
     at Test.main(Test.java:92)
Please help me. I am unable to understand why is it happening. May be that I am doing some silly mistake.

Answer 1

dhirendra_logicon wrote:
The Exception is as follows:
Exception in thread "main" java.lang.NullPointerException
     at Test.loadConfiguration(Test.java:52)
     at Test.<init>(Test.java:29)
     at Test.main(Test.java:92)
Please help me. I am unable to understand why is it happening. May be that I am doing some silly mistake.Well, obviously, m_config is null. You cannot call a method on a null value.