Class StringReader

java.lang.Object

java.io.Reader

java.io.StringReader

All Implemented Interfaces:

AutoCloseable

public class StringReader
extends Reader

A specialized Reader that reads characters from a String in a sequential manner.

See Also:

• StringWriter

Field Summary

Fields inherited from class Reader

lock

Constructor Summary

Constructors

Constructor	Description
StringReader(String str)	Construct a new StringReader with str as source.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes this reader.
void	mark(int readLimit)	Sets a mark position in this reader.
boolean	markSupported()	Indicates whether this reader supports the mark() and reset() methods.
int	read()	Reads a single character from the source string and returns it as an integer with the two higher-order bytes set to 0.
int	read(char[] buf, int offset, int len)	Reads at most len characters from the source string and stores them at offset in the character array buf.
boolean	ready()	Indicates whether this reader is ready to be read without blocking.
void	reset()	Resets this reader's position to the last mark() location.
long	skip(long ns)	Moves ns characters in the source string.

Methods inherited from class Reader

read

Methods inherited from class Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

StringReader

public StringReader(String str)

Construct a new StringReader with str as source. The size of the reader is set to the length() of the string and the Object to synchronize access through is set to str.

Parameters:

str - the source string for this reader.

Method Details

close

public void close()

Closes this reader. Once it is closed, read operations on this reader will throw an IOException. Only the first invocation of this method has any effect.

Specified by:

close in interface AutoCloseable

Specified by:

close in class Reader

mark

public void mark(int readLimit)
          throws IOException

Sets a mark position in this reader. The parameter readLimit is ignored for this class. Calling reset() will reposition the reader back to the marked position.

Overrides:

mark in class Reader

Parameters:

readLimit - ignored for StringReader instances.

Throws:

IllegalArgumentException - if readLimit < 0.

IOException - if this reader is closed.

See Also:

• markSupported()
• reset()

markSupported

public boolean markSupported()

Indicates whether this reader supports the mark() and reset() methods. This implementation returns true.

Overrides:

markSupported in class Reader

Returns:

always true.

read

public int read()
         throws IOException

Reads a single character from the source string and returns it as an integer with the two higher-order bytes set to 0. Returns -1 if the end of the source string has been reached.

Overrides:

read in class Reader

Returns:

the character read or -1 if the end of the source string has been reached.

Throws:

IOException - if this reader is closed.

read

public int read(char[] buf,
 int offset,
 int len)
         throws IOException

Reads at most len characters from the source string and stores them at offset in the character array buf. Returns the number of characters actually read or -1 if the end of the source string has been reached.

Specified by:

read in class Reader

Parameters:

buf - the character array to store the characters read.

offset - the initial position in buffer to store the characters read from this reader.

len - the maximum number of characters to read.

Returns:

the number of characters read or -1 if the end of the reader has been reached.

Throws:

IndexOutOfBoundsException - if offset < 0 or len < 0, or if offset + len is greater than the size of buf.

IOException - if this reader is closed.

ready

public boolean ready()
              throws IOException

Indicates whether this reader is ready to be read without blocking. This implementation always returns true.

Overrides:

ready in class Reader

Returns:

always true.

Throws:

IOException - if this reader is closed.

See Also:

• read()
• read(char[], int, int)

reset

public void reset()
           throws IOException

Resets this reader's position to the last mark() location. Invocations of read() and skip() will occur from this new location. If this reader has not been marked, it is reset to the beginning of the source string.

Overrides:

reset in class Reader

Throws:

IOException - if this reader is closed.

See Also:

• mark(int)
• markSupported()

skip

public long skip(long ns)
          throws IOException

Moves ns characters in the source string. Unlike the overridden method, this method may skip negative skip distances: this rewinds the input so that characters may be read again. When the end of the source string has been reached, the input cannot be rewound.

Overrides:

skip in class Reader

Parameters:

ns - the maximum number of characters to skip. Positive values skip forward; negative values skip backward.

Returns:

the number of characters actually skipped. This is bounded below by the number of characters already read and above by the number of characters remaining:
-(num chars already read) <= distance skipped <= num chars remaining.

Throws:

IOException - if this reader is closed.

See Also:

• mark(int)
• markSupported()
• reset()