Java课后题第十七章：17.3（整数求和）

示例：

public class Test {
    public static void main(String[] args) throws IOException {
        try (DataOutputStream output =
                     new DataOutputStream(new FileOutputStream("newText2.dat"))) {
            for (int i = 0; i < 50; i++)
                output.writeInt(i);
        }
        int sum = 0;
        try (DataInputStream input =
                     new DataInputStream(new FileInputStream("newText2.dat"))) {
            while (true)
                sum = sum + input.readInt();
        } catch (EOFException ex) {
            System.out.println(sum);
            System.out.println("is end");
        }
    }
}