我有一个应该加载文本文件并显示/排序数据的程序,但是根本没有显示数据。任何想法,我做错了什么?我只能坚持使用1.4.2 Java。从加载的文本文件输出数据时出错
下面是代码:
import java.io.*;
import java.util.StringTokenizer;
class NewClass {
private static int quantity;
private static String[] name;
public static void main(String args[]) throws Exception {
InputStreamReader kb = new InputStreamReader(System.in);
BufferedReader in;
in = new BufferedReader(kb);
String buffer;
char choice;
boolean fileread=false;
int[]number=new int[quantity];
String[]name=new String[quantity];
String sorttype="";
do
{ //Setup Menu
choice=menu(in);
if(choice=='E')
{
if(fileread)
System.out.println("Data already has been entered");
else
{
fileread=true;
getdata(number,name);
}
}
else if(choice=='D')
{
if(fileread)
display(number,name,in);
else
System.out.println("Must enter data before it is displayed");
}
else if(choice=='S')
{
if(fileread)
sorttype=sort(number,name,in);
else
System.out.println("Must enter data before it is sorted");
}
} while(choice!='X');
}
//Sort Data
public static void sortint(int[] number, String[] name)
{
int i,j;
for(i=0;i<quantity-1;i++)
for(j=i+1;j<quantity;j++)
if(number[i]>number[j])
{
swap(number,i,j);
swap(name,i,j);
}
}
public static void sortstring(String[] name, int[] number)
{
int i,j;
for(i=0;i<quantity-1;i++)
for(j=i+1;j<quantity;j++)
if(name[i].compareToIgnoreCase(name[j])>0)
{
swap(number,i,j);
swap(name,i,j);
}
}
public static void swap(int[] a,int i,int j)
{
int t;
t=a[i];
a[i]=a[j];
a[j]=t;
}
public static void swap(String[] a,int i,int j)
{
String t;
t=a[i];
a[i]=a[j];
a[j]=t;
}
public static String sort(int[] number, String[] name, BufferedReader kb)throws Exception
{
String buffer;
do
{
//Allow user to sort the phone book
System.out.println("What do you want to sort by?");
System.out.println("Number");
System.out.println("Name");
System.out.print("Enter>>");
buffer=kb.readLine();
if(buffer.equalsIgnoreCase("number"))
{
sortint(number,name);
print(name, number,kb);
return buffer;
}
else if(buffer.equalsIgnoreCase("name"))
{
sortstring(name,number);
print(name,number,kb);
return buffer;
}
System.out.println("Invalid entry");
} while(true);
}
public static void print(String[] name, int[] number, BufferedReader kb)throws Exception
{
System.out.println("Sorted data");
System.out.println("Number\tName");
for(int i=0;i<quantity;i++)
System.out.println(number[i]+"\t"+name[i]);
}
public static void display(int[] number, String[] name, BufferedReader kb)throws Exception
{
System.out.println("Number Name");
for(int i=0;i<quantity;i++)
System.out.println(number[i]+" "+name[i]);
}
public static void getdata(int number[],String name[])throws Exception
{
FileReader file = new FileReader("phoneData.txt");
try (BufferedReader input = new BufferedReader(file)) {
int i;
String buffer;
for(i=0;i<quantity;i++)
{
buffer=input.readLine();
StringTokenizer st = new StringTokenizer(buffer, ",");
name[i]=st.nextToken();
number[i]=Integer.parseInt((st.nextToken()).trim());
}
}
}
public static char menu(BufferedReader kb)throws Exception
{
String buffer;
char input;
do
{
System.out.println("\nWhat would you like to do?");
System.out.println("E-Enter phone book data");
System.out.println("D-Display phone book data");
System.out.println("X-Exit program");
System.out.println("S-Sort list");
System.out.print("Enter E, D, X, S>>");
buffer=kb.readLine();
input=(buffer.toUpperCase()).charAt(0);
if(input=='E'||input=='D'||input=='X'||input=='S')
return input;
System.out.println("Invalid entry");
} while(true);
}
}
而且这里是它返回:
What would you like to do?
E-Enter phone book data
D-Display phone book data
X-Exit program
S-Sort list
Enter E, D, X, S>>D
Number Name
What would you like to do?
E-Enter phone book data
D-Display phone book data
X-Exit program
S-Sort list
Enter E, D, X, S>>
任何帮助深表感谢。
超载的方法呢? – Frisbee68
@ user1965245'phoneData.txt'可能只是空的或不存在的(因为swallow异常你不会知道它)...并且你没有检查input.readLine()的返回值,并且你从0读取,到'quantitiy-1'。如果文件的数据量小于数量,那么您将在'StringTokenizer'上得到一个NPE ...并且您似乎没有任何用于输入数据的菜单选项......并且您的'E'菜单选项具有误导性,因为它从文件中读取数据... – A4L
您想要做什么? E-进入电话簿数据 d-显示电话簿数据 X-退出程序 S-排序列表 输入E,d,X,S >> d 编号名称 数字数据应该是在数但它的空白和名称相同 – Frisbee68