Module java.base
Package java.io

Class PrintStream

java.lang.Object
java.io.OutputStream
java.io.FilterOutputStream
java.io.PrintStream
All Implemented Interfaces:
Closeable, Flushable, Appendable, AutoCloseable
Direct Known Subclasses:
LogStream
public class PrintStream extends FilterOutputStream implements Appendable, Closeable
A PrintStream adds functionality to another output stream, namely the ability to print representations of various data values conveniently. Two other features are provided as well. Unlike other output streams, a PrintStream never throws an IOException; instead, exceptional situations merely set an internal flag that can be tested via the checkError method. Optionally, a PrintStream can be created so as to flush automatically; this means that the flush method of the underlying output stream is automatically invoked after a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written.

All characters printed by a PrintStream are converted into bytes using the given encoding or charset, or the default charset if not specified. The PrintWriter class should be used in situations that require writing characters rather than bytes.

This class always replaces malformed and unmappable character sequences with the charset's default replacement string. The CharsetEncoder class should be used when more control over the encoding process is required.

Since:
1.0
See Also:

  • Field Summary

    Fields declared in class java.io.FilterOutputStream

    out

  • Constructor Summary

    Constructors
    Constructor
    Description
    PrintStream(File file)
    Creates a new print stream, without automatic line flushing, with the specified file.
    PrintStream(File file, String csn)
    Creates a new print stream, without automatic line flushing, with the specified file and charset.
    PrintStream(File file, Charset charset)
    Creates a new print stream, without automatic line flushing, with the specified file and charset.
    PrintStream(OutputStream out)
    Creates a new print stream, without automatic line flushing, with the specified OutputStream.
    PrintStream(OutputStream out, boolean autoFlush)
    Creates a new print stream, with the specified OutputStream and line flushing.
    PrintStream(OutputStream out, boolean autoFlush, String encoding)
    Creates a new print stream, with the specified OutputStream, line flushing, and character encoding.
    PrintStream(OutputStream out, boolean autoFlush, Charset charset)
    Creates a new print stream, with the specified OutputStream, line flushing and charset.
    PrintStream(String fileName)
    Creates a new print stream, without automatic line flushing, with the specified file name.
    PrintStream(String fileName, String csn)
    Creates a new print stream, without automatic line flushing, with the specified file name and charset.
    PrintStream(String fileName, Charset charset)
    Creates a new print stream, without automatic line flushing, with the specified file name and charset.

  • Method Summary

    Modifier and Type
    Method
    Description
    PrintStream
    append(char c)
    Appends the specified character to this output stream.
    PrintStream
    append(CharSequence csq)
    Appends the specified character sequence to this output stream.
    PrintStream
    append(CharSequence csq, int start, int end)
    Appends a subsequence of the specified character sequence to this output stream.
    Charset
    charset()
    Returns the charset used in this PrintStream instance.
    boolean
    checkError()
    Flushes the stream if it's not closed and checks its error state.
    protected void
    clearError()
    Clears the error state of this stream.
    void
    close()
    Closes the stream.
    void
    flush()
    Flushes the stream.
    PrintStream
    format(String format, Object... args)
    Writes a formatted string to this output stream using the specified format string and arguments.
    PrintStream
    format(Locale l, String format, Object... args)
    Writes a formatted string to this output stream using the specified format string and arguments.
    void
    print(boolean b)
    Prints a boolean value.
    void
    print(char c)
    Prints a character.
    void
    print(char[] s)
    Prints an array of characters.
    void
    print(double d)
    Prints a double-precision floating-point number.
    void
    print(float f)
    Prints a floating-point number.
    void
    print(int i)
    Prints an integer.
    void
    print(long l)
    Prints a long integer.
    void
    print(Object obj)
    Prints an object.
    void
    print(String s)
    Prints a string.
    PrintStream
    printf(String format, Object... args)
    A convenience method to write a formatted string to this output stream using the specified format string and arguments.
    PrintStream
    printf(Locale l, String format, Object... args)
    A convenience method to write a formatted string to this output stream using the specified format string and arguments.
    void
    println()
    Terminates the current line by writing the line separator string.
    void
    println(boolean x)
    Prints a boolean and then terminates the line.
    void
    println(char x)
    Prints a character and then terminates the line.
    void
    println(char[] x)
    Prints an array of characters and then terminates the line.
    void
    println(double x)
    Prints a double and then terminates the line.
    void
    println(float x)
    Prints a float and then terminates the line.
    void
    println(int x)
    Prints an integer and then terminates the line.
    void
    println(long x)
    Prints a long and then terminates the line.
    void
    println(Object x)
    Prints an Object and then terminates the line.
    void
    println(String x)
    Prints a String and then terminates the line.
    protected void
    setError()
    Sets the error state of the stream to true.
    void
    write(byte[] buf)
    Writes all bytes from the specified byte array to this stream.
    void
    write(byte[] buf, int off, int len)
    Writes len bytes from the specified byte array starting at offset off to this stream.
    void
    write(int b)
    Writes the specified byte to this stream.
    void
    writeBytes(byte[] buf)
    Writes all bytes from the specified byte array to this stream.

    Methods declared in class java.io.OutputStream

    nullOutputStream

    Methods declared in class java.lang.Object

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

  • Constructor Details

    • PrintStream

      public PrintStream(OutputStream out)
      Creates a new print stream, without automatic line flushing, with the specified OutputStream. Characters written to the stream are converted to bytes using the default charset, or where out is a PrintStream, the charset used by the print stream.
      Parameters:
      out - The output stream to which values and objects will be printed
      See Also:

    • PrintStream

      public PrintStream(OutputStream out, boolean autoFlush)
      Creates a new print stream, with the specified OutputStream and line flushing. Characters written to the stream are converted to bytes using the default charset, or where out is a PrintStream, the charset used by the print stream.
      Parameters:
      out - The output stream to which values and objects will be printed
      autoFlush - Whether the output buffer will be flushed whenever a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written
      See Also:

    • PrintStream

      public PrintStream(OutputStream out, boolean autoFlush, String encoding) throws UnsupportedEncodingException
      Creates a new print stream, with the specified OutputStream, line flushing, and character encoding.
      Parameters:
      out - The output stream to which values and objects will be printed
      autoFlush - Whether the output buffer will be flushed whenever a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written
      encoding - The name of a supported character encoding
      Throws:
      UnsupportedEncodingException - If the named encoding is not supported
      Since:
      1.4

    • PrintStream

      public PrintStream(OutputStream out, boolean autoFlush, Charset charset)
      Creates a new print stream, with the specified OutputStream, line flushing and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.
      Parameters:
      out - The output stream to which values and objects will be printed
      autoFlush - Whether the output buffer will be flushed whenever a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written
      charset - A charset
      Since:
      10

    • PrintStream

      public PrintStream(String fileName) throws FileNotFoundException
      Creates a new print stream, without automatic line flushing, with the specified file name. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the default charset for this instance of the Java virtual machine.
      Parameters:
      fileName - The name of the file to use as the destination of this print stream. If the file exists, then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
      Throws:
      FileNotFoundException - If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
      SecurityException - If a security manager is present and checkWrite(fileName) denies write access to the file
      Since:
      1.5
      See Also:

    • PrintStream

      public PrintStream(String fileName, String csn) throws FileNotFoundException, UnsupportedEncodingException
      Creates a new print stream, without automatic line flushing, with the specified file name and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.
      Parameters:
      fileName - The name of the file to use as the destination of this print stream. If the file exists, then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
      csn - The name of a supported charset
      Throws:
      FileNotFoundException - If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
      SecurityException - If a security manager is present and checkWrite(fileName) denies write access to the file
      UnsupportedEncodingException - If the named charset is not supported
      Since:
      1.5

    • PrintStream

      public PrintStream(String fileName, Charset charset) throws IOException
      Creates a new print stream, without automatic line flushing, with the specified file name and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.
      Parameters:
      fileName - The name of the file to use as the destination of this print stream. If the file exists, then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
      charset - A charset
      Throws:
      IOException - if an I/O error occurs while opening or creating the file
      SecurityException - If a security manager is present and checkWrite(fileName) denies write access to the file
      Since:
      10

    • PrintStream

      public PrintStream(File file) throws FileNotFoundException
      Creates a new print stream, without automatic line flushing, with the specified file. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the default charset for this instance of the Java virtual machine.
      Parameters:
      file - The file to use as the destination of this print stream. If the file exists, then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
      Throws:
      FileNotFoundException - If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
      SecurityException - If a security manager is present and checkWrite(file.getPath()) denies write access to the file
      Since:
      1.5
      See Also:

    • PrintStream

      public PrintStream(File file, String csn) throws FileNotFoundException, UnsupportedEncodingException
      Creates a new print stream, without automatic line flushing, with the specified file and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.
      Parameters:
      file - The file to use as the destination of this print stream. If the file exists, then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
      csn - The name of a supported charset
      Throws:
      FileNotFoundException - If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
      SecurityException - If a security manager is present and checkWrite(file.getPath()) denies write access to the file
      UnsupportedEncodingException - If the named charset is not supported
      Since:
      1.5

    • PrintStream

      public PrintStream(File file, Charset charset) throws IOException
      Creates a new print stream, without automatic line flushing, with the specified file and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.
      Parameters:
      file - The file to use as the destination of this print stream. If the file exists, then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
      charset - A charset
      Throws:
      IOException - if an I/O error occurs while opening or creating the file
      SecurityException - If a security manager is present and checkWrite(file.getPath()) denies write access to the file
      Since:
      10

  • Method Details

    • flush

      public void flush()
      Flushes the stream. This is done by writing any buffered output bytes to the underlying output stream and then flushing that stream.
      Specified by:
      flush in interface Flushable
      Overrides:
      flush in class FilterOutputStream
      See Also:

    • close

      public void close()
      Closes the stream. This is done by flushing the stream and then closing the underlying output stream.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class FilterOutputStream
      See Also:

    • checkError

      public boolean checkError()
      Flushes the stream if it's not closed and checks its error state.
      Returns:
      true if and only if this stream has encountered an IOException, or the setError method has been invoked

    • setError

      protected void setError()
      Sets the error state of the stream to true.

      This method will cause subsequent invocations of checkError() to return true until clearError() is invoked.

      Since:
      1.1

    • clearError

      protected void clearError()
      Clears the error state of this stream.

      This method will cause subsequent invocations of checkError() to return false until another write operation fails and invokes setError().

      Since:
      1.6

    • write

      public void write(int b)
      Writes the specified byte to this stream. If the byte is a newline and automatic flushing is enabled then the flush method will be invoked on the underlying output stream.

      Note that the byte is written as given; to write a character that will be translated according to the default charset, use the print(char) or println(char) methods.

      Overrides:
      write in class FilterOutputStream
      Parameters:
      b - The byte to be written
      See Also:

    • write

      public void write(byte[] buf, int off, int len)
      Writes len bytes from the specified byte array starting at offset off to this stream. If automatic flushing is enabled then the flush method will be invoked on the underlying output stream.

      Note that the bytes will be written as given; to write characters that will be translated according to the default charset, use the print(char) or println(char) methods.

      Overrides:
      write in class FilterOutputStream
      Parameters:
      buf - A byte array
      off - Offset from which to start taking bytes
      len - Number of bytes to write
      Throws:
      IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
      See Also:

    • write

      public void write(byte[] buf) throws IOException
      Writes all bytes from the specified byte array to this stream. If automatic flushing is enabled then the flush method will be invoked on the underlying output stream.

      Note that the bytes will be written as given; to write characters that will be translated according to the default charset, use the print(char[]) or println(char[]) methods.

      Overrides:
      write in class FilterOutputStream
      API Note:
      Although declared to throw IOException, this method never actually does so. Instead, like other methods that this class overrides, it sets an internal flag which may be tested via the checkError() method. To write an array of bytes without having to write a catch block for the IOException, use either writeBytes(buf) or write(buf, 0, buf.length).
      Implementation Requirements:
      This method is equivalent to this.write(buf, 0, buf.length).
      Parameters:
      buf - A byte array
      Throws:
      IOException - If an I/O error occurs.
      Since:
      14
      See Also:

    • writeBytes

      public void writeBytes(byte[] buf)
      Writes all bytes from the specified byte array to this stream. If automatic flushing is enabled then the flush method will be invoked.

      Note that the bytes will be written as given; to write characters that will be translated according to the default charset, use the print(char[]) or println(char[]) methods.

      Implementation Requirements:
      This method is equivalent to this.write(buf, 0, buf.length).
      Parameters:
      buf - A byte array
      Since:
      14

    • print

      public void print(boolean b)
      Prints a boolean value. The string produced by String.valueOf(boolean) is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the write(int) method.
      Parameters:
      b - The boolean to be printed
      See Also:

    • print

      public void print(char c)
      Prints a character. The character is translated into one or more bytes according to the character encoding given to the constructor, or the default charset if none specified. These bytes are written in exactly the manner of the write(int) method.
      Parameters:
      c - The char to be printed
      See Also:

    • print

      public void print(int i)
      Prints an integer. The string produced by String.valueOf(int) is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the write(int) method.
      Parameters:
      i - The int to be printed
      See Also:

    • print

      public void print(long l)
      Prints a long integer. The string produced by String.valueOf(long) is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the write(int) method.
      Parameters:
      l - The long to be printed
      See Also:

    • print

      public void print(float f)
      Prints a floating-point number. The string produced by String.valueOf(float) is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the write(int) method.
      Parameters:
      f - The float to be printed
      See Also:

    • print

      public void print(double d)
      Prints a double-precision floating-point number. The string produced by String.valueOf(double) is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the write(int) method.
      Parameters:
      d - The double to be printed
      See Also:

    • print

      public void print(char[] s)
      Prints an array of characters. The characters are converted into bytes according to the character encoding given to the constructor, or the default charset if none specified. These bytes are written in exactly the manner of the write(int) method.
      Parameters:
      s - The array of chars to be printed
      Throws:
      NullPointerException - If s is null
      See Also:

    • print

      public void print(String s)
      Prints a string. If the argument is null then the string "null" is printed. Otherwise, the string's characters are converted into bytes according to the character encoding given to the constructor, or the default charset if none specified. These bytes are written in exactly the manner of the write(int) method.
      Parameters:
      s - The String to be printed
      See Also:

    • print

      public void print(Object obj)
      Prints an object. The string produced by the String.valueOf(Object) method is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the write(int) method.
      Parameters:
      obj - The Object to be printed
      See Also:

    • println

      public void println()
      Terminates the current line by writing the line separator string. The line separator string is defined by the system property line.separator, and is not necessarily a single newline character ('\n').

    • println

      public void println(boolean x)
      Prints a boolean and then terminates the line. This method behaves as though it invokes print(boolean) and then println().
      Parameters:
      x - The boolean to be printed

    • println

      public void println(char x)
      Prints a character and then terminates the line. This method behaves as though it invokes print(char) and then println().
      Parameters:
      x - The char to be printed.

    • println

      public void println(int x)
      Prints an integer and then terminates the line. This method behaves as though it invokes print(int) and then println().
      Parameters:
      x - The int to be printed.

    • println

      public void println(long x)
      Prints a long and then terminates the line. This method behaves as though it invokes print(long) and then println().
      Parameters:
      x - a The long to be printed.

    • println

      public void println(float x)
      Prints a float and then terminates the line. This method behaves as though it invokes print(float) and then println().
      Parameters:
      x - The float to be printed.

    • println

      public void println(double x)
      Prints a double and then terminates the line. This method behaves as though it invokes print(double) and then println().
      Parameters:
      x - The double to be printed.

    • println

      public void println(char[] x)
      Prints an array of characters and then terminates the line. This method behaves as though it invokes print(char[]) and then println().
      Parameters:
      x - an array of chars to print.

    • println

      public void println(String x)
      Prints a String and then terminates the line. This method behaves as though it invokes print(String) and then println().
      Parameters:
      x - The String to be printed.

    • println

      public void println(Object x)
      Prints an Object and then terminates the line. This method calls at first String.valueOf(x) to get the printed object's string value, then behaves as though it invokes print(String) and then println().
      Parameters:
      x - The Object to be printed.

    • printf

      public PrintStream printf(String format, Object... args)
      A convenience method to write a formatted string to this output stream using the specified format string and arguments.

      An invocation of this method of the form out.printf(format, args) behaves in exactly the same way as the invocation 

      
     out.format(format, args)
      Parameters:
      format - A format string as described in Format string syntax
      args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java Virtual Machine Specification. The behaviour on a null argument depends on the conversion.
      Returns:
      This output stream
      Throws:
      IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
      NullPointerException - If the format is null
      Since:
      1.5

    • printf

      public PrintStream printf(Locale l, String format, Object... args)
      A convenience method to write a formatted string to this output stream using the specified format string and arguments.

      An invocation of this method of the form out.printf(l, format, args) behaves in exactly the same way as the invocation 

      
     out.format(l, format, args)
      Parameters:
      l - The locale to apply during formatting. If l is null then no localization is applied.
      format - A format string as described in Format string syntax
      args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java Virtual Machine Specification. The behaviour on a null argument depends on the conversion.
      Returns:
      This output stream
      Throws:
      IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
      NullPointerException - If the format is null
      Since:
      1.5

    • format

      public PrintStream format(String format, Object... args)
      Writes a formatted string to this output stream using the specified format string and arguments.

      The locale always used is the one returned by Locale.getDefault(Locale.Category) with FORMAT category specified, regardless of any previous invocations of other formatting methods on this object.

      Parameters:
      format - A format string as described in Format string syntax
      args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java Virtual Machine Specification. The behaviour on a null argument depends on the conversion.
      Returns:
      This output stream
      Throws:
      IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
      NullPointerException - If the format is null
      Since:
      1.5

    • format

      public PrintStream format(Locale l, String format, Object... args)
      Writes a formatted string to this output stream using the specified format string and arguments.
      Parameters:
      l - The locale to apply during formatting. If l is null then no localization is applied.
      format - A format string as described in Format string syntax
      args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java Virtual Machine Specification. The behaviour on a null argument depends on the conversion.
      Returns:
      This output stream
      Throws:
      IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
      NullPointerException - If the format is null
      Since:
      1.5

    • append

      public PrintStream append(CharSequence csq)
      Appends the specified character sequence to this output stream.

      An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation 

      
     out.print(csq.toString())

      Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking then toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

      Specified by:
      append in interface Appendable
      Parameters:
      csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this output stream.
      Returns:
      This output stream
      Since:
      1.5

    • append

      public PrintStream append(CharSequence csq, int start, int end)
      Appends a subsequence of the specified character sequence to this output stream.

      An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation 

      
     out.print(csq.subSequence(start, end).toString())
      Specified by:
      append in interface Appendable
      Parameters:
      csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
      start - The index of the first character in the subsequence
      end - The index of the character following the last character in the subsequence
      Returns:
      This output stream
      Throws:
      IndexOutOfBoundsException - If start or end are negative, start is greater than end, or end is greater than csq.length()
      Since:
      1.5

    • append

      public PrintStream append(char c)
      Appends the specified character to this output stream.

      An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation 

      
     out.print(c)
      Specified by:
      append in interface Appendable
      Parameters:
      c - The 16-bit character to append
      Returns:
      This output stream
      Since:
      1.5

    • charset

      public Charset charset()
      Returns the charset used in this PrintStream instance.
      Returns:
      the charset used in this PrintStream instance
      Since:
      18