扫描仪使用定界符但无法识别其后的整数
Scanner using delimiter but not recognizing the integer after it
我似乎无法在我的代码中找到问题,并且想知道这里的好人是否愿意帮助我。我的教授要求我们根据从她提供给我们的文件中提取的信息创建一个二维数组。使用扫描仪和文件 class 我们应该能够完成此操作,但是,我遇到了减速带。我的扫描仪无法识别我为其设置的分隔符后的整数。这是她提供给我们的文件。
5x7
o,2,3
7,1,3
7,1,1
X,4,2
此信息由块引用中有空格的换行符分隔。
这是我的代码:
import java.io.*;
import java.util.*;
public class Battlefield {
// Use the FILL_CHAR for a space that contains no creature.
// Use these chars for creatures so that your code will pass
// the tests used for evaluating your program.
public final char FILL_CHAR = '-';
public final char OGRE = 'o';
public final char CENTAUR = '7';
public final char DRAGON = 'X';
private char[][] field;
public Battlefield(String fn) {
try {
// You write code here.
// Read a file and initialize the field.
// The name of the file is passed in from the driver.
// Keep all the file reading stuff in the try/catch block
// to make file exceptions easier to deal with.
File battlefield = new File(fn);
Scanner scan = new Scanner(battlefield);
scan.useDelimiter("x");
int row = scan.nextInt();
System.out.println(row);
System.out.println(scan.next());
System.out.println(scan.hasNextInt());
int column = scan.nextInt();
char[][] field = new char[row][column];
/**
Scanner scan2 = new Scanner(battlefield);
scan2.useDelimiter(",");
/**
field[scan2.nextInt()][scan2.nextInt()] = OGRE;
field[scan2.nextInt()][scan2.nextInt()] = CENTAUR;
field[scan2.nextInt()][scan2.nextInt()] = CENTAUR;
field[scan2.nextInt()][scan2.nextInt()] = DRAGON;
**/
} catch (IOException ex) {
System.err.println(ex.getStackTrace());
}
}
还有我的主要 method/driver class:
public class BattlefieldDrv {
public static void main(String[] args)
{
Battlefield battlefieldOne = new Battlefield("1field.dat");
System.out.println(battlefieldOne.toString());
}
}
这是我的堆栈跟踪:
> 5
7
o,2,3
7,1,3
7,1,1
X,4,2
false
Exception in thread "main" java.util.InputMismatchException
at java.base/java.util.Scanner.throwFor(Unknown Source)
at java.base/java.util.Scanner.next(Unknown Source)
at java.base/java.util.Scanner.nextInt(Unknown Source)
at java.base/java.util.Scanner.nextInt(Unknown Source)
at Battlefield.<init>(Battlefield.java:38)
at BattlefieldDrv.main(BattlefieldDrv.java:15)
感谢您提供的任何帮助或见解!
让我们逐步完成这段代码。
scan.useDelimiter("x");
int row = scan.nextInt();
5 读入 row
.
System.out.println(row);
5 被打印出来。
System.out.println(scan.next());
文件的其余部分被读取和打印,因为那是x
.
之后的内容
System.out.println(scan.hasNextInt());
没有什么可看的了,所以NoSuchElementException
就扔在这里了。
您需要让扫描仪也接受换行符作为分隔符;你可以使用
scan.useDelimiter("(x|\s)");
(\s
是 "any whitespace" 的模式)。
作为旁注,使用 try-with-resources
-construct 是一个很好的做法:
try (Scanner scan = new Scanner(Paths.get("1field.dat"))) {
scan.useDelimiter(...);
...
} catch (IOException e) {
这将导致您的文件资源被自动关闭。
我似乎无法在我的代码中找到问题,并且想知道这里的好人是否愿意帮助我。我的教授要求我们根据从她提供给我们的文件中提取的信息创建一个二维数组。使用扫描仪和文件 class 我们应该能够完成此操作,但是,我遇到了减速带。我的扫描仪无法识别我为其设置的分隔符后的整数。这是她提供给我们的文件。
5x7
o,2,3
7,1,3
7,1,1
X,4,2
此信息由块引用中有空格的换行符分隔。
这是我的代码:
import java.io.*;
import java.util.*;
public class Battlefield {
// Use the FILL_CHAR for a space that contains no creature.
// Use these chars for creatures so that your code will pass
// the tests used for evaluating your program.
public final char FILL_CHAR = '-';
public final char OGRE = 'o';
public final char CENTAUR = '7';
public final char DRAGON = 'X';
private char[][] field;
public Battlefield(String fn) {
try {
// You write code here.
// Read a file and initialize the field.
// The name of the file is passed in from the driver.
// Keep all the file reading stuff in the try/catch block
// to make file exceptions easier to deal with.
File battlefield = new File(fn);
Scanner scan = new Scanner(battlefield);
scan.useDelimiter("x");
int row = scan.nextInt();
System.out.println(row);
System.out.println(scan.next());
System.out.println(scan.hasNextInt());
int column = scan.nextInt();
char[][] field = new char[row][column];
/**
Scanner scan2 = new Scanner(battlefield);
scan2.useDelimiter(",");
/**
field[scan2.nextInt()][scan2.nextInt()] = OGRE;
field[scan2.nextInt()][scan2.nextInt()] = CENTAUR;
field[scan2.nextInt()][scan2.nextInt()] = CENTAUR;
field[scan2.nextInt()][scan2.nextInt()] = DRAGON;
**/
} catch (IOException ex) {
System.err.println(ex.getStackTrace());
}
}
还有我的主要 method/driver class:
public class BattlefieldDrv {
public static void main(String[] args)
{
Battlefield battlefieldOne = new Battlefield("1field.dat");
System.out.println(battlefieldOne.toString());
}
}
这是我的堆栈跟踪:
> 5
7
o,2,3
7,1,3
7,1,1
X,4,2
false
Exception in thread "main" java.util.InputMismatchException
at java.base/java.util.Scanner.throwFor(Unknown Source)
at java.base/java.util.Scanner.next(Unknown Source)
at java.base/java.util.Scanner.nextInt(Unknown Source)
at java.base/java.util.Scanner.nextInt(Unknown Source)
at Battlefield.<init>(Battlefield.java:38)
at BattlefieldDrv.main(BattlefieldDrv.java:15)
感谢您提供的任何帮助或见解!
让我们逐步完成这段代码。
scan.useDelimiter("x");
int row = scan.nextInt();
5 读入 row
.
System.out.println(row);
5 被打印出来。
System.out.println(scan.next());
文件的其余部分被读取和打印,因为那是x
.
System.out.println(scan.hasNextInt());
没有什么可看的了,所以NoSuchElementException
就扔在这里了。
您需要让扫描仪也接受换行符作为分隔符;你可以使用
scan.useDelimiter("(x|\s)");
(\s
是 "any whitespace" 的模式)。
作为旁注,使用 try-with-resources
-construct 是一个很好的做法:
try (Scanner scan = new Scanner(Paths.get("1field.dat"))) {
scan.useDelimiter(...);
...
} catch (IOException e) {
这将导致您的文件资源被自动关闭。