我已经开始学习 Java，并且遇到了一个应该将一些内容写入numbers.dat文件的简单程序的问题。
我面临两个问题：
我得到的输出如下：
2, 6, 12, 20, 30, 42, 56, 72, 90, 110, 132, 156, 182, 210, 240, 272, 306, 342, 380, 420, 462, 506, 552, 600, 650, 702, 756, 812, 870, 930, 992, 1056, 1122, 1190, 1260, 1332, 1406, 1482, 1560, 1640, 1722, 1806, 1892, 1980, 2070, 35562, 2450, 24556, 2 ..
什么时候应该：
对于偶数：
2,4,6,8,10,12,14,……,98,100
对于奇数：
2,4,6,8,10,12,14,……,98,100,1,3,5,7,9,……..97,99
我的第二个问题是输出没有写入
numbers.dat文件！都是空白。
我试图解决的书中的问题是：
编写一个名为 TextFileIO.java 的程序来创建一个名为 numbers.dat 的文件。然后创建一个算法，写入从 1 到 100 的所有偶数整数，用逗号分隔。
创建文件后，关闭并重新打开文件并将结果显示在屏幕上。显示结果后，将 1 到 100 的奇数整数附加到文件末尾，用逗号分隔。重新打开文件并显示结果。文件的内容应该是从 1 到 100 的偶数，用逗号分隔，然后是从 1 到 100 的奇数，用逗号分隔。该程序的输出将类似于以下内容：
2,4,6,8,10,12,14,……,98,100
2,4,6,8,10,12,14,……,98,100,1,3,5,7,9,……..97,99
以下是我到目前为止尝试过的代码：
文本文件IO.java
package package1;
import java.io.*;
import java.util.*;
//class definition
public class textFileIO{
//The main function
public static void main(String args[]) {
//This declares a file to open.
File outFile = new File("numbers.dat");
int sumEven = 0;
int sumOdd = 0;
//File IO requires a try/catch block to prevent the program from crashing
try {
//a buffered writer is used to allow us to write to the file.
BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));
//This for loop handles adding all of the numbers together
for(int i = 1; i < 100; i += 2) {
sumEven += i + 1;
writer.write("" + sumEven + ", ");
}
//adding a new line and closing the file
writer.newLine();
writer.close();
//A buffered Reader is used for reading a new file.
BufferedReader reader = new BufferedReader(new FileReader(outFile));
//Because I only add a new line at the end, I only need to read the first line.
System.out.println(reader.readLine());
//I need to write again, so I close the reader and open the writer.
reader.close();
//you need to create another object to append to the file
//writer.open();
BufferedWriter writer2 = new BufferedWriter(new FileWriter(outFile));
//This for loop is identical to the previous one, except for odd numbers
for(int i = 1; i < 100; i += 2) {
sumOdd += i;
writer2.write("" + sumOdd + ", ");
}
writer.newLine();
writer.close();
//The same here. You need to create another reader
//reader.open();
BufferedReader reader2 = new BufferedReader(new FileReader(outFile));
System.out.println(reader2.readLine());
}
catch (Exception e) {
}
}
}
编辑 2
我更改了我的代码，这是我最新的代码。我仍然有问题。控制台输出屏幕显示 49 和 50 作为输出，我的 numbers.dat 文件现在仅显示逗号分隔的奇数列表。我现在做错了什么？
import java.io.*;
import java.util.*;
public class TextFileIO {
public static void main(String[] args) throws Exception {
//Clear the contents of numbers.dat if already exists and populated
File fileOne = new File("numbers.dat");
fileOne.delete();
File newFile = new File("numbers.dat");
newFile.createNewFile();
//Create writer object
PrintWriter writer = new PrintWriter(new FileWriter("numbers.dat"));
//Loop from 1 to 100
for (int i = 1; i <= 100; i++) {
//If number is even, write to file
if (i % 2 == 0) {
writer.print(i + ",");
}
}
//Close writer object.
writer.close();
//Read from file
FileInputStream fileStream = new FileInputStream("numbers.dat");
DataInputStream in = new DataInputStream(fileStream);
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
//Print line
System.out.println(reader.read());
reader.close();
//Write all odd numbers to file
PrintWriter writer2 = new PrintWriter(new FileWriter("numbers.dat"));
//Loop from 1 to 100
for (int i = 1; i <= 100; i++) {
//If number is odd, write to file
if (i % 2 == 1) {
writer2.print(i + ",");
}
}
writer2.close();
//Read from file
FileInputStream fileStream2 = new FileInputStream("numbers.dat");
DataInputStream in2 = new DataInputStream(fileStream2);
BufferedReader reader2 = new BufferedReader(new InputStreamReader(in2));
//Print line
System.out.println(reader2.read());
reader.close();
}
}
编辑 3：我仍然无法获得所需的输出。我仍然在控制台中得到 49 和 50 的输出，在 numbers.dat 文件中，输出仍然只是用逗号分隔的奇数。我无法理解我的代码到底要改变什么。