Java Scanner class reading strings
I've created a scanner class to read through the text file and get the value what I'm after. Let's assume that I have a text file contains.
List of people: length 3
1 : Fnjiei : ID 7868860 : Age 18
2 : Oipuiieerb : ID 334134 : Age 39
3 : Enekaree : ID 6106274 : Age 31
I'm trying to get a name and id number and age, but everytime I try to run my code it gives me an exception. Here's my code. Any suggestion from java gurus?:) It was able to read one single line....... but no more than a single line of text.
public void readFile(String fileName)throws IOException{
Scanner开发者_如何学Python input = null;
input = new Scanner(new BufferedReader(new FileReader(fileName)));
try {
while (input.hasNextLine()){
int howMany = 3;
System.out.println(howMany);
String userInput = input.nextLine();
String name = "";
String idS = "";
String ageS = "";
int id;
int age;
int count=0;
for (int j = 0; j <= howMany; j++){
for (int i=0; i < userInput.length(); i++){
if(count < 2){ // for name
if(Character.isLetter(userInput.charAt(i))){
name+=userInput.charAt(i); // store the name
}else if(userInput.charAt(i)==':'){
count++;
i++;
}
}else if(count == 2){ // for id
if(Character.isDigit(userInput.charAt(i))){
idS+=userInput.charAt(i); // store the id
}
else if(userInput.charAt(i)==':'){
count++;
i++;
}
}else if(count == 3){ // for age
if(Character.isDigit(userInput.charAt(i))){
ageS+=userInput.charAt(i); // store the age
}
}
id = Integer.parseInt(idS); // convert id to integer
age = Integer.parseInt(ageS); // convert age to integer
Fighters newFighters = new Fighters(id, name, age);
fighterList.add(newFighters);
}
userInput = input.nextLine();
}
}
}finally{
if (input != null){
input.close();
}
}
}
My appology if my mere code begs to be changed.
Edited It gives me a number format exception!!! I dont know how many empty space would be there between these values.
Here's a solution that uses only Scanner
API, the important one being findInLine
. It can handle minor syntactic variations in the input format, and yet it's very readable, requiring no need for fancy regex or magic array indices.
String text =
"List of @#%^$ people : length 3 !@%# \n" +
"1 : Fnjiei : ID 7868860 ::: Age 18\n" +
" 2: Oipuiieerb : ID 334134 : Age 39 (old, lol!) \r\n" +
" 3 : Enekaree : ID 6106274 => Age 31\n";
Scanner sc = new Scanner(text);
sc.findInLine("length");
final int N = sc.nextInt();
for (int i = 0; i < N; i++) {
sc.nextLine();
sc.findInLine(":");
String name = sc.next();
sc.findInLine("ID");
long id = sc.nextLong();
sc.findInLine("Age");
int age = sc.nextInt();
System.out.printf("[%s] %s (%s)%n", id, name, age);
}
This prints:
[7868860] Fnjiei (18)
[334134] Oipuiieerb (39)
[6106274] Enekaree (31)
API links
Scanner.findInLine(Pattern pattern)
- Attempts to find the next occurrence of the specified pattern ignoring delimiters.
- Use this
Pattern.compile
overload if performance is an issue
This seems to be shorter:
public void readFile(String fileName)throws IOException
{
Scanner input = null;
input = new Scanner(new BufferedReader(new FileReader(fileName)));
String userInput;
try
{
while (input.hasNextLine())
{
userInput = input.nextLine().trim();
if (userInput.length() > 0)
{
String[] userInfo = userInput.split(":");
int count = Integer.parseInt(userInfo[0].trim());
String name = userInfo[1].trim();
int id = Integer.parseInt(userInfo[2].trim().split("\\s+")[1].trim());
int age = Integer.parseInt(userInfo[3].trim().split("\\s+")[1].trim());
System.out.println("Count: " + count + " Name: " + name + " ID:" + id + " Age:" + age);
}
Fighters newFighters = new Fighters(id, name, age);
fighterList.add(newFighters);
}
}
finally
{
if (input != null)
{
input.close();
}
}
}
For the input you have us, it prints this:
Count: 1 Name: Fnjiei ID:7868860 Age:18
Count: 2 Name: Oipuiieerb ID:334134 Age:39
Count: 3 Name: Enekaree ID:6106274 Age:31
More information about the split method can be found here. I basically first split the line by using the :
as delimiter, then, I split again using the \\s+
, which basically splits a string and return an array containing the words that were separated by white spaces.
Scanner input = null;
input = new Scanner(new BufferedReader(new FileReader("filename")));
try{
while(input.hasNextLine()){
String userInput = input.nextLine();
String[] data = userInput.split(":");
System.out.println("Name: "+data[1]+" ID:"+data[2].split("\\s+")[2]+
" Age:"+data[3].split("\\s+")[2]);
}
}finally{
if(input != null)
input.close();
}
Above snippet shows the basic idea.Also please keep in mind that this might not be the optimal solution.
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