Mega Code Archive
Paying attention to exceptions in constructors
<![CDATA[
// : c09:Cleanup.java
// Paying attention to exceptions in constructors.
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
class InputFile {
private BufferedReader in;
public InputFile(String fname) throws Exception {
try {
in = new BufferedReader(new FileReader(fname));
// Other code that might throw exceptions
} catch (FileNotFoundException e) {
System.err.println("Could not open " + fname);
// Wasn't open, so don't close it
throw e;
} catch (Exception e) {
// All other exceptions must close it
try {
in.close();
} catch (IOException e2) {
System.err.println("in.close() unsuccessful");
}
throw e; // Rethrow
} finally {
// Don't close it here!!!
}
}
public String getLine() {
String s;
try {
s = in.readLine();
} catch (IOException e) {
throw new RuntimeException("readLine() failed");
}
return s;
}
public void dispose() {
try {
in.close();
System.out.println("dispose() successful");
} catch (IOException e2) {
throw new RuntimeException("in.close() failed");
}
}
}
public class Cleanup {
public static void main(String[] args) {
try {
InputFile in = new InputFile("Cleanup.java");
String s;
int i = 1;
while ((s = in.getLine()) != null)
; // Perform line-by-line processing here...
in.dispose();
} catch (Exception e) {
System.err.println("Caught Exception in main");
e.printStackTrace();
}
}
} ///:~
]]>