java.lang.Object
- edu.princeton.cs.algs4.In

```
public final class In
extends java.lang.Object
```
Input. This class provides methods for reading strings and numbers from standard input, file input, URLs, and sockets.
The Locale used is: language = English, country = US. This is consistent with the formatting conventions with Java floating-point literals, command-line arguments (via Double.parseDouble(String)) and standard output.
For additional documentation, see Section 3.1 of Computer Science: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.
Like Scanner, reading a token also consumes preceding Java whitespace, reading a full line consumes the following end-of-line delimeter, while reading a character consumes nothing extra.
Whitespace is defined in Character.isWhitespace(char). Newlines consist of \n, \r, \r\n, and Unicode hex code points 0x2028, 0x2029, 0x0085; see Scanner.java (NB: Java 6u23 and earlier uses only \r, \r, \r\n).

构造器概要

构造器
构造器	说明
`In()`	Initializes an input stream from standard input.
`In(java.io.File file)`	Initializes an input stream from a file.
`In(java.lang.String name)`	Initializes an input stream from a filename or web page name.
`In(java.net.Socket socket)`	Initializes an input stream from a socket.
`In(java.net.URL url)`	Initializes an input stream from a URL.
`In(java.util.Scanner scanner)`	Initializes an input stream from a given `Scanner` source; use with `new Scanner(String)` to read from a string.

方法概要

修饰符和类型	方法	说明
`void`	`close()`	Closes this input stream.
`boolean`	`exists()`	Returns true if this input stream exists.
`boolean`	`hasNextChar()`	Returns true if this input stream has more input (including whitespace).
`boolean`	`hasNextLine()`	Returns true if this input stream has a next line.
`boolean`	`isEmpty()`	Returns true if input stream is empty (except possibly whitespace).
`static void`	`main(java.lang.String[] args)`	Unit tests the `In` data type.
`java.lang.String`	`readAll()`	Reads and returns the remainder of this input stream, as a string.
`double[]`	`readAllDoubles()`	Reads all remaining tokens from this input stream, parses them as doubles, and returns them as an array of doubles.
`int[]`	`readAllInts()`	Reads all remaining tokens from this input stream, parses them as integers, and returns them as an array of integers.
`java.lang.String[]`	`readAllLines()`	Reads all remaining lines from this input stream and returns them as an array of strings.
`long[]`	`readAllLongs()`	Reads all remaining tokens from this input stream, parses them as longs, and returns them as an array of longs.
`java.lang.String[]`	`readAllStrings()`	Reads all remaining tokens from this input stream and returns them as an array of strings.
`boolean`	`readBoolean()`	Reads the next token from this input stream, parses it as a `boolean` (interpreting either `"true"` or `"1"` as `true`, and either `"false"` or `"0"` as `false`).
`byte`	`readByte()`	Reads the next token from this input stream, parses it as a `byte`, and returns the `byte`.
`char`	`readChar()`	Reads and returns the next character in this input stream.
`double`	`readDouble()`	Reads the next token from this input stream, parses it as a `double`, and returns the `double`.
`static double[]`	`readDoubles()`	已过时。 Replaced by `StdIn.readAllDoubles()`.
`static double[]`	`readDoubles(java.lang.String filename)`	已过时。 Replaced by `new In(filename)`.`readAllDoubles()`.
`float`	`readFloat()`	Reads the next token from this input stream, parses it as a `float`, and returns the `float`.
`int`	`readInt()`	Reads the next token from this input stream, parses it as a `int`, and returns the `int`.
`static int[]`	`readInts()`	已过时。 Replaced by `StdIn.readAllInts()`.
`static int[]`	`readInts(java.lang.String filename)`	已过时。 Replaced by `new In(filename)`.`readAllInts()`.
`java.lang.String`	`readLine()`	Reads and returns the next line in this input stream.
`long`	`readLong()`	Reads the next token from this input stream, parses it as a `long`, and returns the `long`.
`short`	`readShort()`	Reads the next token from this input stream, parses it as a `short`, and returns the `short`.
`java.lang.String`	`readString()`	Reads the next token from this input stream and returns it as a `String`.
`static java.lang.String[]`	`readStrings()`	已过时。 Replaced by `StdIn.readAllStrings()`.
`static java.lang.String[]`	`readStrings(java.lang.String filename)`	已过时。 Replaced by `new In(filename)`.`readAllStrings()`.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 构造器详细资料
  - In
```
public In()
```
    Initializes an input stream from standard input.
  - In
```
public In(java.net.Socket socket)
```
    Initializes an input stream from a socket.
    
    参数:
    
    socket - the socket
    
    抛出:
    
    java.lang.IllegalArgumentException - if cannot open socket
    
    java.lang.IllegalArgumentException - if socket is null
  - In
```
public In(java.net.URL url)
```
    Initializes an input stream from a URL.
    
    参数:
    
    url - the URL
    
    抛出:
    
    java.lang.IllegalArgumentException - if cannot open url
    
    java.lang.IllegalArgumentException - if url is null
  - In
```
public In(java.io.File file)
```
    Initializes an input stream from a file.
    
    参数:
    
    file - the file
    
    抛出:
    
    java.lang.IllegalArgumentException - if cannot open file
    
    java.lang.IllegalArgumentException - if file is null
  - In
```
public In(java.lang.String name)
```
    Initializes an input stream from a filename or web page name.
    
    参数:
    
    name - the filename or web page name
    
    抛出:
    
    java.lang.IllegalArgumentException - if cannot open name as a file or URL
    
    java.lang.IllegalArgumentException - if name is null
  - In
```
public In(java.util.Scanner scanner)
```
    Initializes an input stream from a given Scanner source; use with new Scanner(String) to read from a string.
    Note that this does not create a defensive copy, so the scanner will be mutated as you read on.
    
    参数:
    
    scanner - the scanner
    
    抛出:
    
    java.lang.IllegalArgumentException - if scanner is null
- 方法详细资料
  - exists
```
public boolean exists()
```
    Returns true if this input stream exists.
    
    返回:
    
    true if this input stream exists; false otherwise
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if input stream is empty (except possibly whitespace). Use this to know whether the next call to readString(), readDouble(), etc will succeed.
    
    返回:
    
    true if this input stream is empty (except possibly whitespace); false otherwise
  - hasNextLine
```
public boolean hasNextLine()
```
    Returns true if this input stream has a next line. Use this method to know whether the next call to readLine() will succeed. This method is functionally equivalent to hasNextChar().
    
    返回:
    
    true if this input stream has more input (including whitespace); false otherwise
  - hasNextChar
```
public boolean hasNextChar()
```
    Returns true if this input stream has more input (including whitespace). Use this method to know whether the next call to readChar() will succeed. This method is functionally equivalent to hasNextLine().
    
    返回:
    
    true if this input stream has more input (including whitespace); false otherwise
  - readLine
```
public java.lang.String readLine()
```
    Reads and returns the next line in this input stream.
    
    返回:
    
    the next line in this input stream; null if no such line
  - readChar
```
public char readChar()
```
    Reads and returns the next character in this input stream.
    
    返回:
    
    the next char in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
  - readAll
```
public java.lang.String readAll()
```
    Reads and returns the remainder of this input stream, as a string.
    
    返回:
    
    the remainder of this input stream, as a string
  - readString
```
public java.lang.String readString()
```
    Reads the next token from this input stream and returns it as a String.
    
    返回:
    
    the next String in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
  - readInt
```
public int readInt()
```
    Reads the next token from this input stream, parses it as a int, and returns the int.
    
    返回:
    
    the next int in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as an int
  - readDouble
```
public double readDouble()
```
    Reads the next token from this input stream, parses it as a double, and returns the double.
    
    返回:
    
    the next double in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as a double
  - readFloat
```
public float readFloat()
```
    Reads the next token from this input stream, parses it as a float, and returns the float.
    
    返回:
    
    the next float in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as a float
  - readLong
```
public long readLong()
```
    Reads the next token from this input stream, parses it as a long, and returns the long.
    
    返回:
    
    the next long in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as a long
  - readShort
```
public short readShort()
```
    Reads the next token from this input stream, parses it as a short, and returns the short.
    
    返回:
    
    the next short in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as a short
  - readByte
```
public byte readByte()
```
    Reads the next token from this input stream, parses it as a byte, and returns the byte.
    To read binary data, use BinaryIn.
    
    返回:
    
    the next byte in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as a byte
  - readBoolean
```
public boolean readBoolean()
```
    Reads the next token from this input stream, parses it as a boolean (interpreting either "true" or "1" as true, and either "false" or "0" as false).
    
    返回:
    
    the next boolean in this input stream
    
    抛出:
    
    java.util.NoSuchElementException - if the input stream is empty
    
    java.util.InputMismatchException - if the next token cannot be parsed as a boolean
  - readAllStrings
```
public java.lang.String[] readAllStrings()
```
    Reads all remaining tokens from this input stream and returns them as an array of strings.
    
    返回:
    
    all remaining tokens in this input stream, as an array of strings
  - readAllLines
```
public java.lang.String[] readAllLines()
```
    Reads all remaining lines from this input stream and returns them as an array of strings.
    
    返回:
    
    all remaining lines in this input stream, as an array of strings
  - readAllInts
```
public int[] readAllInts()
```
    Reads all remaining tokens from this input stream, parses them as integers, and returns them as an array of integers.
    
    返回:
    
    all remaining lines in this input stream, as an array of integers
  - readAllLongs
```
public long[] readAllLongs()
```
    Reads all remaining tokens from this input stream, parses them as longs, and returns them as an array of longs.
    
    返回:
    
    all remaining lines in this input stream, as an array of longs
  - readAllDoubles
```
public double[] readAllDoubles()
```
    Reads all remaining tokens from this input stream, parses them as doubles, and returns them as an array of doubles.
    
    返回:
    
    all remaining lines in this input stream, as an array of doubles
  - close
```
public void close()
```
    Closes this input stream.
  - readInts
```
@Deprecated
public static int[] readInts(java.lang.String filename)
```
    已过时。
    Replaced by new In(filename).readAllInts().
    
    Reads all integers from a file and returns them as an array of integers.
    
    参数:
    
    filename - the name of the file
    
    返回:
    
    the integers in the file
  - readDoubles
```
@Deprecated
public static double[] readDoubles(java.lang.String filename)
```
    已过时。
    Replaced by new In(filename).readAllDoubles().
    
    Reads all doubles from a file and returns them as an array of doubles.
    
    参数:
    
    filename - the name of the file
    
    返回:
    
    the doubles in the file
  - readStrings
```
@Deprecated
public static java.lang.String[] readStrings(java.lang.String filename)
```
    已过时。
    Replaced by new In(filename).readAllStrings().
    
    Reads all strings from a file and returns them as an array of strings.
    
    参数:
    
    filename - the name of the file
    
    返回:
    
    the strings in the file
  - readInts
```
@Deprecated
public static int[] readInts()
```
    已过时。
    Replaced by StdIn.readAllInts().
    
    Reads all integers from standard input and returns them an array of integers.
    
    返回:
    
    the integers on standard input
  - readDoubles
```
@Deprecated
public static double[] readDoubles()
```
    已过时。
    Replaced by StdIn.readAllDoubles().
    
    Reads all doubles from standard input and returns them as an array of doubles.
    
    返回:
    
    the doubles on standard input
  - readStrings
```
@Deprecated
public static java.lang.String[] readStrings()
```
    已过时。
    Replaced by StdIn.readAllStrings().
    
    Reads all strings from standard input and returns them as an array of strings.
    
    返回:
    
    the strings on standard input
  - main
```
public static void main(java.lang.String[] args)
```
    Unit tests the In data type.
    
    参数:
    
    args - the command-line arguments

类 In

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

In

In

In

In

In

In

方法详细资料

exists

isEmpty

hasNextLine

hasNextChar

readLine

readChar

readAll

readString

readInt

readDouble

readFloat

readLong

readShort

readByte

readBoolean

readAllStrings

readAllLines

readAllInts

readAllLongs

readAllDoubles

close

readInts

readDoubles

readStrings

readInts

readDoubles

readStrings

main