我为我的uni Assignment编写了这个程序。主要思想是，当调用addItem时，它会在该文件上创建一个文本文件并从用户写入顺序。但它怎么只创建文件但内部没有打印任何东西。
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
public class OrderedFood extends Food {
private int quantity;
private boolean isSet;
private SetDrink setDrink;
public OrderedFood(){
quantity = 0;
isSet = false;
setDrink = null;
}
public OrderedFood(String foodCode, String foodName,boolean isSet, SetDrink setDrink, int quantity){
super(foodCode, foodName);
this.isSet = isSet;
this.quantity = quantity;
this.setDrink = setDrink;
}
public int getquantity(){
return quantity;
}
public void setquantity(int quantity){
this.quantity = quantity;
}
public boolean getIsSet(){
return isSet;
}
public void setisSet(boolean isSet){
this.isSet = isSet;
}
public SetDrink getsetDrink(){
return setDrink;
}
public void setsetDrink(SetDrink setDrink){
this.setDrink = setDrink;
}
public void addItem (String foodCode, int TabNum)throws IOException{
clearScreen(); // invoking the clearScreen method
String filename = Integer.toString(TabNum);
try
{
//this blocks creates a table by the table num
File file = new File("/tmp", filename);
System.out.println("path=" + file.getAbsolutePath());
file.createNewFile();
System.out.println("File created");
}
catch(Exception e)
{
e.printStackTrace();
System.out.println("Failed to create file");
}
try (Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(filename), "utf-8")))
{
writer.write("foodCode"); // this syntax prints the order
writer.close();
}
}
public void deleteItem(String foodCode , int TabNum)throws IOException{
clearScreen();
String Tab = Integer.toString(TabNum);
remove(Tab,foodCode);// we just invoke the remove method, which will then remove the item from the .txt file
}
public static void clearScreen() { // this method clears the screen.
System.out.print("\033[H\033[2J");
System.out.flush();
}
public void remove(String file, String lineToRemove)throws IOException {
try {
File inFile = new File(file);
if (!inFile.isFile()) {
System.out.println("Parameter is not an existing file");
return;
}
File tempFile = new File(inFile.getAbsolutePath() + ".tmp");
BufferedReader buff = new BufferedReader(new FileReader(file));
PrintWriter kap = new PrintWriter(new FileWriter(tempFile));
String line = null;
while ((line = buff.readLine()) != null) {
if (!line.trim().equals(lineToRemove)) {
kap.println(line);
kap.flush();
}
}
kap.close();
buff.close();
if (!inFile.delete()) {
System.out.println("Could not delete file");
return;
}
if (!tempFile.renameTo(inFile))
System.out.println("Could not rename file");
} catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
答案 0 :(得分：0)
当您创建一个文件时，如果您在打开文件时没有告诉扩展名以写入您使用的文件名，但是它只包含选项卡编号而不是文件的完整路径，则使用以下代码时会出现逻辑错误
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
public class OrderedFood extends Food {
private int quantity;
private boolean isSet;
private SetDrink setDrink;
public OrderedFood(){
quantity = 0;
isSet = false;
setDrink = null;
}
public OrderedFood(String foodCode, String foodName,boolean isSet, SetDrink setDrink, int quantity){
super(foodCode, foodName);
this.isSet = isSet;
this.quantity = quantity;
this.setDrink = setDrink;
}
public int getquantity(){
return quantity;
}
public void setquantity(int quantity){
this.quantity = quantity;
}
public boolean getIsSet(){
return isSet;
}
public void setisSet(boolean isSet){
this.isSet = isSet;
}
public SetDrink getsetDrink(){
return setDrink;
}
public void setsetDrink(SetDrink setDrink){
this.setDrink = setDrink;
}
public void addItem (String foodCode, int TabNum)throws IOException{
clearScreen(); // invoking the clearScreen method
String filename = Integer.toString(TabNum);
try
{
//this blocks creates a table by the table num
File file = new File("/tmp", filename);
System.out.println("path=" + file.getAbsolutePath());
file.createNewFile();
filename = file.getAbsolutePath(); //here the actual address is updated to use later
System.out.println("File created");
}
catch(Exception e)
{
e.printStackTrace();
System.out.println("Failed to create file");
}
try
{
//now here we need that address updated earlier not just the tabnumber
PrintWriter writer = new PrintWriter(filename, "UTF-8");
writer.print("food code");
riter.close();
}
}
public void deleteItem(String foodCode , int TabNum)throws IOException{
clearScreen();
String Tab = Integer.toString(TabNum);
remove(Tab,foodCode);// we just invoke the remove method, which will then remove the item from the .txt file
}
public static void clearScreen() { // this method clears the screen.
System.out.print("\033[H\033[2J");
System.out.flush();
}
public void remove(String file, String lineToRemove)throws IOException {
try {
File inFile = new File(file);
if (!inFile.isFile()) {
System.out.println("Parameter is not an existing file");
return;
}
File tempFile = new File(inFile.getAbsolutePath() + ".tmp");
BufferedReader buff = new BufferedReader(new FileReader(file));
PrintWriter kap = new PrintWriter(new FileWriter(tempFile));
String line = null;
while ((line = buff.readLine()) != null) {
if (!line.trim().equals(lineToRemove)) {
kap.println(line);
kap.flush();
}
}
kap.close();
buff.close();
if (!inFile.delete()) {
System.out.println("Could not delete file");
return;
}
if (!tempFile.renameTo(inFile))
System.out.println("Could not rename file");
} catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}