java檔案資料排序

Question

輸入:建立一個文字檔INPUT.TXT內容為為每一行一個字

輸出:開啟INPUT.TXT,讀入檔案中 資料,將資料排序(從小到 ),將資料輸出到OUTPUT.TXT格式仍然是每一行一個數字

Answer 1

請參考我的做法。

import java.util.*;
import java.io.*;
public class A {
public static void main(String[] args) throws Exception {
Scanner input = new Scanner(new File("input.txt"));
ArrayList al = new ArrayList();
while (input.hasNextLine()) {
al.add(input.nextLine());
}
input.close();
int[] ary = new int[al.size()];
for (int i = 0; i < ary.length; i++) {
ary[i] = Integer.parseInt((String)al.get(i));
}
Arrays.sort(ary);

PrintWriter output = new PrintWriter(new File("output.txt"));
for (int i = 0; i < ary.length; i++) {
output.println(ary[i]);
}
output.close();
}
}

Answer 2

TreeSet set = new TreeSet();
try {
BufferedReader BR =
new BufferedReader(new FileReader(new File("INPUT.TXT")));
String getStr = null;
while((getStr = BR.readLine())!=null)
set.add(getStr);
BR.close();
} catch (FileNotFoundException e) {
} catch (IOException ioe){
}

try {
BufferedWriter BW =
new BufferedWriter(new FileWriter(new File("OUTPUT.TXT")));
Iterator it = set.iterator();
while(it.hasNext()){
BW.write(it.next());
BW.newLine();
}
BW.close();
} catch (FileNotFoundException e) {
} catch (IOException ioe){
}