这是我编写的一个简单程序，用于对 txt 文件中的整数进行计算。经过几个小时的调试尝试，我希望有一双新的眼睛能发现我的一些问题。编辑：data.txt 包含整数 1-5。每行一个整数。
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Scanner;
public class Calculator {
public static int[] NUMBERS; //global value for the array
public static void main(String[] args) throws FileNotFoundException {
File file = new File("data.txt");
Scanner sc = new Scanner(file);
List x = new ArrayList();
while (sc.hasNextInt()) {
x.add(sc.nextInt());
}
NUMBERS = new int[x.size()];
Iterator<Integer> iterator = x.iterator();
for (int i = 0; i < NUMBERS.length; i++) {
NUMBERS[i] = iterator.next().intValue();
}
sc.close();
Scanner sc2 = new Scanner(file);
System.out.println("Welcome to Calculation Program!\n");
startMenus(sc2);
}
private static void startMenus(Scanner sca) throws FileNotFoundException {
while (true) {
System.out.println("(Enter option # and press ENTER)\n");
System.out.println("1. Display the average of the list");
System.out.println("2. Display the number of occurences of a given element in the list");
System.out.println("3. Display the prime numbers in a list");
System.out.println("4. Display the information above in table form");
System.out.println("5. Save the information onto a file in table form");
System.out.println("6. Exit");
int option = sca.nextInt();
sca.nextLine();
switch (option) {
case 1:
infoMenu1(sca);
break;
case 2:
infoMenu2(sca);
break;
case 3:
infoMenu3(sca);
break;
case 4:
infoMenu4(sca);
break;
case 5:
infoMenu5(sca);
break;
case 6:
System.exit(0);
default:
System.out.println("Unrecognized Option!\n");
}
}
}
private static void infoMenu1(Scanner sc2) {
System.out.println("The average of the numbers in the file is: " + avg(NUMBERS));
}
public static double avg(int[] numbers) {
int sum = 0;
for (int i = 0; i < numbers.length; i++) {
sum = (sum + numbers[i]);
}
return (sum / numbers.length);
}
public static int occr(int[] numbers, int x) {
int count = 0;
for (int n : numbers) {
if (n == x) {
count = count + 1;
}
}
return count;
}
public static boolean prime(int x) {
boolean answer = true;
if (x == 0 || x == 1) {
return false;
}
for (int i = 2; i <= x / 2; i = i + 1) {
if (i != x) {
if (x % i == 0) {
answer = false;
}
}
}
return answer;
}
public static int[] primes(int[] numbers) {
int primesCount = 0;
for (int i : numbers) {
if (prime(i)) {
primesCount = (primesCount + 1);
}
}
if (primesCount == 0) {
return null;
}
int[] result = new int[primesCount];
int index = 0;
for (int i : numbers) {
if (prime(i)) {
result[index] = i;
index = index + 1;
}
}
return result;
}
private static void infoMenu2(Scanner sc) {
sc = new Scanner(System.in);
System.out.println("Which integer would you like to check for number of occurences?");
int choice = sc.nextInt();
System.out.println("The number of occurence(s) of " + choice + " are/is " + occr(NUMBERS, choice));
}
private static void infoMenu3(Scanner sc2) {
int[] myPrimes = primes(NUMBERS);
System.out.println("The prime number(s) in the file are/is: ");
for (int j = 0; j < myPrimes.length; ++j) {
System.out.println(myPrimes[j] + " ");
}
}
private static void infoMenu4(Scanner kb) throws FileNotFoundException {
File file = new File("data.txt");
Scanner sc = new Scanner(file);
int counter = 0;
while (sc.hasNextInt()) {
counter = counter++;
}
int lenth = counter;
int[] column1 = new int[lenth];
while (sc.hasNextInt()) {
column1 = new int[sc.nextInt()];
}
int[] column2 = new int[occr(NUMBERS, sc.nextInt())];
boolean column3 = prime(sc.nextInt());
System.out.printf("Average: " + "%20.2f", column1);
System.out.println();
System.out.printf("Occurences: " + "%14d", column2);
System.out.println();
System.out.printf("Primes:" + "%19s : %s", column3);
System.out.println();
}
private static void infoMenu5(Scanner kb) throws FileNotFoundException {
File file = new File("data.txt");
Scanner sc = new Scanner(file);
PrintWriter pw = new PrintWriter(new File("results.txt"));
int counter = 0;
while (sc.hasNextInt()) {
counter = counter++;
}
int lenth = counter;
int[] column1 = new int[lenth];
while (sc.hasNextInt()) {
column1 = new int[sc.nextInt()];
}
int[] column2 = new int[occr(NUMBERS, sc.nextInt())];
boolean column3 = prime(sc.nextInt());
pw.printf("Number: " + "%-10d", column1);
pw.println();
pw.printf("Occurences: " + "%12d", column2);
pw.println();
pw.printf("Primes:" + "%24s : %s", column3);
pw.println();
pw.close();
}
}