行的检查是在带有缓冲区读取和哈希集的文件中。
行的检查是在带有缓冲区读取和哈希集的文件中。
提问于 2012-03-10 17:56:49
我的问题是，我必须编写代码来检查客户名称是否已经在我的txt文件(Customers.txt)中。
问题是，我检查了哈希集，如果客户在文件中，他说他不在文件中。(手动检查)请帮助我解决这个问题。
我已经拥有的代码如下。
public class Customer {
//declaration
public static String S;
private String line ;
public String nameCustomer;
/**
* constructor
*/
public Klant(){}
/**Checking of the customer is in the file
*/
public void getCustomer() {
// make SimpleInOutDialog
SimpleInOutDialog input = new SimpleInOutDialog("Customers");
nameCustomer = input.readString("Give in the name");
try{
BufferedReader br = new BufferedReader(new FileReader("L:\\Documents/Informatica/6de jaar/GIP/Customers.txt"));
HashSet<String> hs = new HashSet<String>();
int i = 0;
while ((line = br.readLine()) != null)
{
i++;
if (i == 1){hs.add(br.readLine());}
if (i % 4 == 0){hs.add(br.readLine());}
}
if(hs.contains(nameCustomer)){
//the customer exists
input.showString("The customer exists", "");
}else{input.showString("The customer does not exist, we will make a new one", "");
setNieuweKlant();}
}catch (Exception e){//Catch when there are errors
System.err.println("Error: " + e.getMessage());}
}
/**
* make a new customer
*/
public void Make new customer(){
// make SimpleInOutDialog
SimpleInOutDialog input = new SimpleInOutDialog("A new customer");
//input
S = "Name customer: " + input.readString("Give in your name:");
WriteToFile();
S = "Adress: " + input.readString("Give your adress");
WriteToFile();
S = "Telephonenummber: " + input.readString("Give your telephonenumber");
WriteToFile();
//making a customerID
UUID idCustomer = UUID.randomUUID();
S = "CustomerID: " + customerID.toString();
WriteToFile();
}
/**
* Schrijft de gegevens weg naar het bestand
*/
public void WriteToFile(){
try{
FileWriter writer = new FileWriter("L:\\Documents/Informatica/6de jaar/GIP/Customer.txt", true);
BufferedWriter out = new BufferedWriter(writer);
//Wrting away your data
out.write(S);
//Closing the writer
out.close();
}catch (Exception e){//Catch when there are errors
System.err.println("Error: " + e.getMessage());
}
}荷兰代码
public class Klant {
//declaratie van de variabele die de tekst voorsteld
public static String S;
private String line ;
public String naamklant;
/**
* constructor
*/
public Klant(){}
/**Controleerd of de klant al bestaat
*/
public void getKlant() {
// SimpleInOutDialog aanmaken
SimpleInOutDialog input = new SimpleInOutDialog("Klanten");
naamklant = input.readString("Geef de volledige naam in");
try{
BufferedReader br = new BufferedReader(new FileReader("L:\\Documents/Informatica/6de jaar/GIP/Klanten.txt"));
HashSet<String> hs = new HashSet<String>();
int i = 0;
while ((line = br.readLine()) != null)
{
i++;
if (i == 1){hs.add(br.readLine());}
if (i % 4 == 0){hs.add(br.readLine());}
}
if(hs.contains(naamklant)){
//klant bestaat
input.showString("De klant bestaat", "");
}else{input.showString("De klant bestaat niet, er wordt een nieuwe klant aangemaakt", "");
setNieuweKlant();}
}catch (Exception e){//Catch wanneer er errors zijn
System.err.println("Error: " + e.getMessage());}
}
/**
* Maakt een nieuwe klant aan
*/
public void setNieuweKlant(){
// SimpleInOutDialog aanmaken
SimpleInOutDialog input = new SimpleInOutDialog("Een nieuwe klant");
//input
S = input.readString("Geef de volledige naam in");
WriteToFile();
S = "Adres: " + input.readString("Geef het adres op");
WriteToFile();
S = "Telefoonummer: " + input.readString("Geef het telefoonnummer op");
WriteToFile();
//een klantennummer aanmaken
UUID idKlant = UUID.randomUUID();
S = "Klantnummer: " + idKlant.toString();
WriteToFile();
}
/**
* Schrijft de gegevens weg naar het bestand
*/
public void WriteToFile(){
try{
FileWriter writer = new FileWriter("L:\\Documents/Informatica/6de jaar/GIP/Klanten.txt", true);
BufferedWriter out = new BufferedWriter(writer);
//uw gegevens wegschrijven
out.write(S);
out.newLine();
//de writer sluiten
out.close();
}catch (Exception e){//Catch wanneer er errors zijn
System.err.println("Error: " + e.getMessage());}
}
}回答 2
Stack Overflow用户
回答已采纳
发布于 2012-03-10 19:02:05
我真的不确定您总体上想做什么(每4行读取一次)，但是如果您只想检查文件中是否存在字符串，我就不会使用HashSet。
下面是一个完整的程序，用于检查文件中是否存在字符串：
import java.io.*;
public class CheckName
{
private static boolean doesNameExistInFile(String name, String filename)
throws FileNotFoundException, IOException
{
BufferedReader reader = new BufferedReader(new FileReader(filename));
String line = null;
try {
while ((line = reader.readLine()) != null) {
if (line.equals(name))
return true;
}
} finally {
// Always close() before exiting.
reader.close();
}
return false;
}
public static void main(String[] args)
throws FileNotFoundException, IOException
{
boolean exists = doesNameExistInFile("Bender", "input.txt");
System.out.println(exists ? "Exists!" : "Does not exist.");
}
}输入文件input.txt的内容
Leela
Fry
Professor
Hermes
Zoidberg有几件事要注意：
- 我们不读取整个文件。一旦找到字符串，我们就停止阅读，因为这是我们感兴趣的所有内容。
- 总是在退出之前一直在
close()，不管是否找到了字符串。我们将调用放在finally块中.
Stack Overflow用户
发布于 2012-03-10 18:28:15
这是：
while ((line = br.readLine()) != null)
{
i++;
if (i == 1){hs.add(br.readLine());}
if (i % 4 == 0){hs.add(br.readLine());}
}应该是这样的：
while ((line = br.readLine()) != null)
{
i++;
if (i == 1)
hs.add(line);
if (i % 4 == 0)
hs.add(line);
}也就是说，您可能意味着add您刚刚读过的行，而不是在新行中阅读，并对其进行add处理。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/9648803
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