我编写了这段代码并且差不多完成了，但是我很想知道如何在我的代码中实现filereader，将数据从文件放入现有的数据列表/数组中。我已经在网站上查看了如何将文件读取器放入，但是一直被语法困扰:(我也被迫坚持使用Java 1.4.2，所以我不能使用Scanner和那些东西。
以下是不完整的代码：
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
//Import libraries
public class phoneBook
{
static ArrayList ListNumbers = new ArrayList(); //Create array
public static void main(String[] args)
{
InputStreamReader inp = null;
BufferedReader input = null;//Create inputstreamreader and bufferedreader
int nOption = 0;
try
{
inp = new InputStreamReader(System.in);
input = new BufferedReader(inp);
while(true)
{
System.out.println("Welcome to PDA Phonebook");
System.out.println(" " + "\nWhat would you like to do?");
System.out.println("1. Enter Phone Numbers/ Add a Phone Number.");
System.out.println("2. Modify Phone Number.");
System.out.println("3. Delete Phone Number.");
System.out.println("4. Sort Phone Number.");
System.out.println("5. Show all Phone Numbers.");
System.out.println("6. Load Phone Numbers.");
System.out.println("7. Exit.");
System.out.println("\nChoose an option(1-7) >> ");
nOption = Integer.parseInt(input.readLine());
//Layout visual menu
switch(nOption)
{
case 1:
AddNumber(input);
break;
case 2:
ModifyNumber(input);
break;
case 3:
DeleteNumber(input);
break;
case 4:
SortNumber(input);
break;
case 5:
ShowAllNumbers();
break;
case 6:
LoadNumbers(input);
break;
case 7:
System.out.println("Exiting program. Press any key to continue....");
input.read();
System.exit(0);
break;
//Create cases for the input of the user
}
}
}
catch(Exception exp)
{
}
}
//create private static void for each option in the list
private static void AddNumber(BufferedReader input) throws IOException
{
NumberTemplate tmpObject = null;
tmpObject = new NumberTemplate();//create tmp object for new phone numbers
while(true)
{
System.out.println("Name belonging to the phone number >> ");
tmpObject.NumberName = input.readLine().toString();//Convert input of name to a string
System.out.println("Phone Number");
tmpObject.Number = input.readLine().toString(); //Convert input of phone number to a string
if(tmpObject != null)
ListNumbers.add(tmpObject);//Add the new phone number to the list of numbers
System.out.println("\n Do you want to add another phone number?(y/n) >>");
if(!input.readLine().toLowerCase().equals("y"))//Ask user if they want to add another number
break;//Return to list
}
}
private static void ModifyNumber(BufferedReader input) throws IOException
{
NumberTemplate tmpObject = null;
System.out.println("Name of the number to modify >> ");
String OldNumberName = input.readLine();//User inputs name of number they want to edit
int index = getNumberIndexByName(OldNumberName);
if(index == -1)//if the number does not exist
{
System.out.println(" Number belonging to " + OldNumberName+ " not found.");//Tell the user if they entered an nonexistant number name
}
else//if number does exist
{
tmpObject = (NumberTemplate)ListNumbers.get(index);
showNumber(tmpObject);
System.out.println("What you want to modify (Name|Number)? >>");
String strOption = input.readLine();//User chooses what they want to edit from the number
if("name".equals(strOption.toLowerCase()))
{
System.out.println("New Name belonging to the number >> ");
tmpObject.NumberName = input.readLine().toString();//User inputs the name they want to change the number to
}
else if("number".equals(strOption.toLowerCase()))
{
System.out.println("New number "+tmpObject.NumberName);
tmpObject.Number = input.readLine().toString();//User inputs the number they want to change
}
else
{
System.out.println("Unable to locate the property entered..");
}
ListNumbers.set(index, tmpObject);//Apply the changes to the list of numbers
}
}
private static int getNumberIndexByName(String Name)
{
int index = -1;
NumberTemplate tmp =null;
for(int i=0;i<ListNumbers.size();i++)
{
tmp = (NumberTemplate)ListNumbers.get(i);
if(tmp.NumberName.toLowerCase().equals(Name.toLowerCase()))
{
index = i;
break;
}
}
return index;//List numbers
}
private static void showNumber(NumberTemplate tnumber)
{
System.out.println(tnumber.NumberName+"\t\t"+tnumber.Number);
}
private static void DeleteNumber(BufferedReader input) throws IOException
{
System.out.println("Name of the number to delete >> ");
String OldNumberName = input.readLine();
int index = getNumberIndexByName(OldNumberName);
if(index == -1)//If number name doesn't exist
{
System.out.println(" Number belonging to " + OldNumberName+ " not found.");
}
else//if number name exists
{
ListNumbers.remove(index);//Remove the number from list of numbers
System.out.println(" Number belonging to " + OldNumberName+ "deleted successfully.");
}
}
private static void SortNumber(BufferedReader input) throws IOException
{
System.out.println("Enter the key to sort (Name|Number)? >>");
String strOption = input.readLine();//User inputs what they want to sort the numbers by
int nSize = ListNumbers.size();
String str1, str2;
if("name".equals(strOption.toLowerCase()))//Sort numbers by name
{
for(int i = 0;i<nSize;i++)
{
for(int j = (i+1);j<nSize;j++)
{
str1 = ((NumberTemplate)ListNumbers.get(i)).NumberName;
str2 = ((NumberTemplate)ListNumbers.get(j)).NumberName;
if(str1.compareToIgnoreCase(str2) > 0)
{
NumberTemplate tmp = (NumberTemplate) ListNumbers.get(i);
ListNumbers.set(i, (NumberTemplate) ListNumbers.get(j));
ListNumbers.set(j, tmp);
}
}
}
}
else if("number".equals(strOption.toLowerCase()))//Sort numbers by number
{
for(int i = 0;i<nSize;i++)
{
for(int j = (i+1);j<nSize;j++)
{
str1 = ((NumberTemplate)ListNumbers.get(i)).Number;
str2 = ((NumberTemplate)ListNumbers.get(j)).Number;
if(str1.compareToIgnoreCase(str2) > 0)
{
NumberTemplate tmp = (NumberTemplate) ListNumbers.get(i);
ListNumbers.set(i, (NumberTemplate) ListNumbers.get(j));
ListNumbers.set(j, tmp);
}
}
}
}
else
{
System.out.println("Unable to locate the property entered..");
}
ShowAllNumbers();
}
private static void ShowAllNumbers()
{
System.out.println("PDA Phone Book\n");//List all the numbers
System.out.println("Name\t\tNumber");
for(int i=0;i<ListNumbers.size();i++)
{
showNumber((NumberTemplate)ListNumbers.get(i));
}
}
private static void LoadNumbers(BufferedReader input) throws FileNotFoundException, IOException
{
{BufferedReader in = new BufferedReader(new FileReader("phoneBook.txt"));
while(true)
{
NumberTemplate tmpObject = null;
String line = in.readLine();
if (line == null)
break;
NumberTemplate nt = new NumberTemplate();
nt.NumberName = line;
line = in.readLine();
nt.Number = Integer.parseInt(line);
ListNumbers.add(nt);
}
}
}
class NumberTemplate
{
public String NumberName = "";
public String Number = "";
}
}
这就是我遇到问题的地方：
private static void LoadNumbers(BufferedReader input) throws FileNotFoundException, IOException
{
{BufferedReader in = new BufferedReader(new FileReader("phoneBook.txt"));
while(true)
{
NumberTemplate tmpObject = null;
String line = in.readLine();
if (line == null)
break;
NumberTemplate nt = new NumberTemplate();
nt.NumberName = line;
line = in.readLine();
nt.Number = Integer.parseInt(line);
ListNumbers.add(nt);
}
}
出现以下错误：
C:\Java\bin>javac phoneBook.java
phoneBook.java:81: error: non-static variable this cannot be referenced from a s
tatic context
tmpObject = new NumberTemplate();//create tmp object for new phone numbe
rs
^
phoneBook.java:240: error: non-static variable this cannot be referenced from a
static context
NumberTemplate nt = new NumberTemplate();
^
phoneBook.java:243: error: incompatible types
nt.Number = Integer.parseInt(line);
^
required: String
found: int
Note: phoneBook.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
3 errors
该文件由45个名称和数字组成，格式为：
name
number
name
number
etc....
答案 0 :(得分：1)
您已将使用input初始化的System.in传递给每个方法。你可能想要像
BufferedReader in = new BufferedReader(new FileReader("foo"));
并将in传递给方法。您需要一个额外的变量，因为您想使用标准输入流和文件输入流。您也可以使用公共字段。
while(true)
{
String line = in.readLine();
if (line == null)
break;
NumberTemplate nt = new NumberTemplate();
nt.NumberName = line;
line = in.readLine();
nt.Number = Integer.parseInt(line);
ListNumbers.add(nt);
}
可能有一些try/catch。
此代码重复直到文件末尾，读取名称，在NumberTemplate实例中设置适当的值，然后解析整数并执行相同操作。最后，它会将其添加到ArrayList。
编译代码
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
//Import libraries
public class phoneBook
{
static ArrayList ListNumbers = new ArrayList(); //Create array
public static void main(String[] args)
{
InputStreamReader inp = null;
BufferedReader input = null;//Create inputstreamreader and bufferedreader
int nOption = 0;
try
{
inp = new InputStreamReader(System.in);
input = new BufferedReader(inp);
while(true)
{
System.out.println("Welcome to PDA Phonebook");
System.out.println(" " + "\nWhat would you like to do?");
System.out.println("1. Enter Phone Numbers/ Add a Phone Number.");
System.out.println("2. Modify Phone Number.");
System.out.println("3. Delete Phone Number.");
System.out.println("4. Sort Phone Number.");
System.out.println("5. Show all Phone Numbers.");
System.out.println("6. Load Phone Numbers.");
System.out.println("7. Exit.");
System.out.println("\nChoose an option(1-7) >> ");
nOption = Integer.parseInt(input.readLine());
//Layout visual menu
switch(nOption)
{
case 1:
AddNumber(input);
break;
case 2:
ModifyNumber(input);
break;
case 3:
DeleteNumber(input);
break;
case 4:
SortNumber(input);
break;
case 5:
ShowAllNumbers();
break;
case 6:
LoadNumbers(input);
break;
case 7:
System.out.println("Exiting program. Press any key to continue....");
input.read();
System.exit(0);
break;
//Create cases for the input of the user
}
}
}
catch(Exception exp)
{
}
}
//create private static void for each option in the list
private static void AddNumber(BufferedReader input) throws IOException
{
NumberTemplate tmpObject = null;
tmpObject = new NumberTemplate();//create tmp object for new phone numbers
while(true)
{
System.out.println("Name belonging to the phone number >> ");
tmpObject.NumberName = input.readLine().toString();//Convert input of name to a string
System.out.println("Phone Number");
tmpObject.Number = input.readLine().toString(); //Convert input of phone number to a string
if(tmpObject != null)
ListNumbers.add(tmpObject);//Add the new phone number to the list of numbers
System.out.println("\n Do you want to add another phone number?(y/n) >>");
if(!input.readLine().toLowerCase().equals("y"))//Ask user if they want to add another number
break;//Return to list
}
}
private static void ModifyNumber(BufferedReader input) throws IOException
{
NumberTemplate tmpObject = null;
System.out.println("Name of the number to modify >> ");
String OldNumberName = input.readLine();//User inputs name of number they want to edit
int index = getNumberIndexByName(OldNumberName);
if(index == -1)//if the number does not exist
{
System.out.println(" Number belonging to " + OldNumberName+ " not found.");//Tell the user if they entered an nonexistant number name
}
else//if number does exist
{
tmpObject = (NumberTemplate)ListNumbers.get(index);
showNumber(tmpObject);
System.out.println("What you want to modify (Name|Number)? >>");
String strOption = input.readLine();//User chooses what they want to edit from the number
if("name".equals(strOption.toLowerCase()))
{
System.out.println("New Name belonging to the number >> ");
tmpObject.NumberName = input.readLine().toString();//User inputs the name they want to change the number to
}
else if("number".equals(strOption.toLowerCase()))
{
System.out.println("New number "+tmpObject.NumberName);
tmpObject.Number = input.readLine().toString();//User inputs the number they want to change
}
else
{
System.out.println("Unable to locate the property entered..");
}
ListNumbers.set(index, tmpObject);//Apply the changes to the list of numbers
}
}
private static int getNumberIndexByName(String Name)
{
int index = -1;
NumberTemplate tmp =null;
for(int i=0;i<ListNumbers.size();i++)
{
tmp = (NumberTemplate)ListNumbers.get(i);
if(tmp.NumberName.toLowerCase().equals(Name.toLowerCase()))
{
index = i;
break;
}
}
return index;//List numbers
}
private static void showNumber(NumberTemplate tnumber)
{
System.out.println(tnumber.NumberName+"\t\t"+tnumber.Number);
}
private static void DeleteNumber(BufferedReader input) throws IOException
{
System.out.println("Name of the number to delete >> ");
String OldNumberName = input.readLine();
int index = getNumberIndexByName(OldNumberName);
if(index == -1)//If number name doesn't exist
{
System.out.println(" Number belonging to " + OldNumberName+ " not found.");
}
else//if number name exists
{
ListNumbers.remove(index);//Remove the number from list of numbers
System.out.println(" Number belonging to " + OldNumberName+ "deleted successfully.");
}
}
private static void SortNumber(BufferedReader input) throws IOException
{
System.out.println("Enter the key to sort (Name|Number)? >>");
String strOption = input.readLine();//User inputs what they want to sort the numbers by
int nSize = ListNumbers.size();
String str1, str2;
if("name".equals(strOption.toLowerCase()))//Sort numbers by name
{
for(int i = 0;i<nSize;i++)
{
for(int j = (i+1);j<nSize;j++)
{
str1 = ((NumberTemplate)ListNumbers.get(i)).NumberName;
str2 = ((NumberTemplate)ListNumbers.get(j)).NumberName;
if(str1.compareToIgnoreCase(str2) > 0)
{
NumberTemplate tmp = (NumberTemplate) ListNumbers.get(i);
ListNumbers.set(i, (NumberTemplate) ListNumbers.get(j));
ListNumbers.set(j, tmp);
}
}
}
}
else if("number".equals(strOption.toLowerCase()))//Sort numbers by number
{
for(int i = 0;i<nSize;i++)
{
for(int j = (i+1);j<nSize;j++)
{
str1 = ((NumberTemplate)ListNumbers.get(i)).Number;
str2 = ((NumberTemplate)ListNumbers.get(j)).Number;
if(str1.compareToIgnoreCase(str2) > 0)
{
NumberTemplate tmp = (NumberTemplate) ListNumbers.get(i);
ListNumbers.set(i, (NumberTemplate) ListNumbers.get(j));
ListNumbers.set(j, tmp);
}
}
}
}
else
{
System.out.println("Unable to locate the property entered..");
}
ShowAllNumbers();
}
private static void ShowAllNumbers()
{
System.out.println("PDA Phone Book\n");//List all the numbers
System.out.println("Name\t\tNumber");
for(int i=0;i<ListNumbers.size();i++)
{
showNumber((NumberTemplate)ListNumbers.get(i));
}
}
private static void LoadNumbers(BufferedReader input) throws FileNotFoundException, IOException
{
BufferedReader in = new BufferedReader(new FileReader("phoneBook.txt"));
while(true)
{
NumberTemplate tmpObject = null;
String line = in.readLine();
if (line == null)
break;
NumberTemplate nt = new NumberTemplate();
nt.NumberName = line;
line = in.readLine();
nt.Number = line;
ListNumbers.add(nt);
}
}
}
class NumberTemplate
{
public String NumberName = "";
public String Number = "";
}