Here I would like to discuss about the Loading of a Resource in a Java Application.For example lets take the Java sample eclipse project Test. Here we have different Package as 1. org.work.corejava, 2. org.work.corejava.file.csvreader also 3.org.work.corejava.xml.parser,In the above Example if i want to read the InputData.txt file need to be read in the ResouceLocator.java,
Normally we do as follows.
public class ResourceLocator {
public static void main(String[] args) {
File fileIn = new File("InputData.TXT");
FileReader fileReader = null;
BufferedReader reader = null;
try {
fileReader = new FileReader(fileIn);
reader = new BufferedReader(fileReader);
} catch (FileNotFoundException e) {
e.printStackTrace();
}finally{
try{
reader.close();
}catch(Exception e){}
}
}
}
But It will throw the following Exception
java.io.FileNotFoundException: InputData.TXT (The system cannot find the file specified) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.(Unknown Source) at java.io.FileReader.(Unknown Source) at org.work.corejava.ResourceLocator.main(ResourceLocator.java:25)
The reason behind this Exception is the Application is searching the InputData.TXT in the base class path. Basically inside the SRC Folder. But the File is in the src/org/work/corejava folder. To avoid the above exception we can simply copy the InputData.TXT to the src folder and the issue resolved. otherwise provide the Entire path as follows.
File fileIn = new File("D:\\Development\\workspace\\Test\\org\\work\\corejava\\InputData.TXT");
The best way to do this is by using the Class.getResource Method as follows.
URL url=ResourceLocator.class.getResource("InputData.TXT");
fileReader = new FileReader(url.getFile());
Here we will keep the File and the Java FIle in the same package.
The complete program is as follows.
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
/**
* To find the Resource by using the Java Resource Locator.
* @author askeralim
*
*/
public class ResourceLocator {
public static void main(String[] args) throws IOException {
FileReader fileReader = null;
BufferedReader reader = null;
try {
URL url=ResourceLocator.class.getResource("InputData.TXT");
fileReader = new FileReader(url.getFile());
reader = new BufferedReader(fileReader);
String data =reader.readLine();
System.out.println(data);
} catch (FileNotFoundException e) {
e.printStackTrace();
}finally{
try{
reader.close();
}catch(Exception e){}
}
}
}
