研究一下。它使用了更高级的Java,但理解它是值得的。
package test;
import java.io.*;
import java.util.*;
public class PhoneBill {
private static String BILL_FORMAT = "%-10s $%,6.2f\n";
private static boolean DEBUG=true;
Map<String, List<LineItem>> accounts = new HashMap<String,List<LineItem>>();
public void readFile(String inFileStr) {
FileReader fReader=null;
try {
fReader = new FileReader(inFileStr);
BufferedReader br = new BufferedReader(fReader);
String line;
while ((line = br.readLine()) != null) {
if (line.indexOf("_") != -1)
continue;
else if (!line.isEmpty()) {
LineItem li = new LineItem(line.trim());
List<LineItem> list = accounts.get(li.accNum);
if(list==null){
list = new ArrayList<LineItem>();
accounts.put(li.accNum, list);
}
list.add(li);
}
}
br.close();
} catch (Exception e) {
/* Don't just swallow Exceptions. */
e.printStackTrace();
} finally {
if(fReader!=null){
try{
fReader.close();
} catch(Exception e){
e.printStackTrace();
}
}
}
}
public void processCharges() {
StringBuffer out = new StringBuffer(100)
.append("Invoice\n")
.append("--------------------------\n")
.append("Account Amount Due \n");
double total = 0.0;
double lCharges = 0;
for (String accNum:accounts.keySet()) {
List<LineItem> account = accounts.get(accNum);
lCharges = 10;
for(LineItem li:account){
lCharges += li.getCharges();
}
total += lCharges;
out.append(String.format(BILL_FORMAT, accNum, lCharges));
}
out.append("--------------------------\n");
out.append(String.format(BILL_FORMAT, "Total", total));
writeToFile("invoice.txt", out.toString());
}
private void writeToFile(String filename, String outStr) {
if(DEBUG){
System.out.printf("========%swriteToFile:%s=========\n", '=', filename);
System.out.println(outStr);
System.out.printf("========%swriteToFile:%s=========\n", '/', filename);
}
try {
File file = new File(filename);
// If file doesn't exist, then create it.
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(outStr);
bw.close();
} catch (IOException ioe) {
System.out.println(ioe.getMessage());
}
}
public static void main(String[] args) {
PhoneBill pB = new PhoneBill();
pB.readFile("input_data.txt");
pB.processCharges();
}
static class LineItem {
String accNum;
double timeOfCall;
double mins;
double amountDue;
boolean counted = false;
private static final double EIGHT_AM = convertTime("08:00");
private static final double TEN_PM = convertTime("22:00");
public LineItem(String accStr) {
processAccount(accStr);
}
private void processAccount(String accStr) {
StringTokenizer st = new StringTokenizer(accStr);
accNum = st.nextToken();
timeOfCall = convertTime(st.nextToken());
mins = Double.parseDouble(st.nextToken());
if (timeOfCall > EIGHT_AM && timeOfCall < TEN_PM)
amountDue = mins * 0.10;
else
amountDue = mins * 0.05;
}
public String getAccountNum() {
return accNum;
}
public double getCharges() {
return amountDue;
}
private static double convertTime(String in){
/* Will blow up if `in` isn't given in h:m. */
String[] h_m = in.split(":");
return Double.parseDouble(h_m[0])*60+Double.parseDouble(h_m[1]);
}
}
}
