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如果用戶試圖輸入以前使用的ID號碼 ,我將如何去不保存記錄? 我已經嘗試了一段時間的循環,這是第二次詢問用戶的工作,它不會工作後。我想過使用數組?如何確定一個數字以前是否在變量中使用過?
import java.util.*;
import java.io.*;
public class CreateCustomerFile
{
public static void main(String[] args) throws IOException
{
int pos;
RandomAccessFile it =
new RandomAccessFile("CustomerFile.txt", "rw");
Scanner input = new Scanner(System.in);
int id;
String name;
int zip;
final int RECORDSIZE = 100;
final int NUMRECORDS = 1000;
final int STOP = 99;
try
{
byte [] padding = new byte[RECORDSIZE];
Arrays.fill(padding, (byte)0);
for(int x = 0; x < NUMRECORDS; ++x)
{
it.write(padding);
}
}
catch(IOException e)
{
System.out.println("Error: " + e.getMessage());
}
finally
{
it.close();
}
it =
new RandomAccessFile("CustomerFile.txt","rw");
try
{
System.out.print("Enter ID number" +
" or " + STOP + " to quit ");
id = input.nextInt();
while(id != STOP)
{
input.nextLine();
System.out.print("Enter last name");
name = input.nextLine();
while(name.length() > 7 || name.length() <7)
{
System.out.print("Name must be 7 characters; Enter last name");
name = input.nextLine();
}
System.out.print("Enter zipcode ");
zip = input.nextInt();
pos = id - 1;
it.seek(pos * RECORDSIZE);
it.writeInt(id);
it.writeUTF(name);
it.writeInt(zip);
System.out.print("Enter ID number" +
" or " + STOP + " to quit ");
int id1 = input.nextInt();
if(id == id1)
{
System.out.print("Id has been previously used");
System.out.print("Enter ID number" +
" or " + STOP + " to quit ");
id1 = input.nextInt();
}
id = id1;
}
}
catch(IOException e)
{
System.out.println("Error: " + e.getMessage());
}
finally
{
it.close();
}
}
}
好了,一開始我還錯誤的印象。那麼,通過跟蹤到目前爲止與變量聯繫的方式(重複值的種類)這樣做的唯一方法。說,存儲它--->如果數組可以幫助你在最低水平,希望你知道你需要聲明的數組的長度,否則一些更好的控制像一個分區,集合。然後沖洗掉。 – bonCodigo