JDK8/Java8源码在线阅读
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package java.io;
import java.util.Formatter;
import java.util.Locale;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
/**
* A <code>PrintStream</code> 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 <code>PrintStream</code> never throws an
* <code>IOException</code>; instead, exceptional situations merely set an
* internal flag that can be tested via the <code>checkError</code> method.
* Optionally, a <code>PrintStream</code> can be created so as to flush
* automatically; this means that the <code>flush</code> method is
* automatically invoked after a byte array is written, one of the
* <code>println</code> methods is invoked, or a newline character or byte
* (<code>'\n'</code>) is written.
*
* <p> All characters printed by a <code>PrintStream</code> are converted into
* bytes using the platform's default character encoding. The <code>{@link
* PrintWriter}</code> class should be used in situations that require writing
* characters rather than bytes.
*
* @author Frank Yellin
* @author Mark Reinhold
* @since JDK1.0
*/
public class PrintStream extends FilterOutputStream
implements Appendable, Closeable
{
private final boolean autoFlush;
private boolean trouble = false;
private Formatter formatter;
/**
* Track both the text- and character-output streams, so that their buffers
* can be flushed without flushing the entire stream.
*/
private BufferedWriter textOut;
private OutputStreamWriter charOut;
/**
* requireNonNull is explicitly declared here so as not to create an extra
* dependency on java.util.Objects.requireNonNull. PrintStream is loaded
* early during system initialization.
*/
private static <T> T requireNonNull(T obj, String message) {
if (obj == null)
throw new NullPointerException(message);
return obj;
}
/**
* Returns a charset object for the given charset name.
* @throws NullPointerException is csn is null
* @throws UnsupportedEncodingException if the charset is not supported
*/
private static Charset toCharset(String csn)
throws UnsupportedEncodingException
{
requireNonNull(csn, "charsetName");
try {
return Charset.forName(csn);
} catch (IllegalCharsetNameException|UnsupportedCharsetException unused) {
// UnsupportedEncodingException should be thrown
throw new UnsupportedEncodingException(csn);
}
}
/* Private constructors */
private PrintStream(boolean autoFlush, OutputStream out) {
super(out);
this.autoFlush = autoFlush;
this.charOut = new OutputStreamWriter(this);
this.textOut = new BufferedWriter(charOut);
}
private PrintStream(boolean autoFlush, OutputStream out, Charset charset) {
super(out);
this.autoFlush = autoFlush;
this.charOut = new OutputStreamWriter(this, charset);
this.textOut = new BufferedWriter(charOut);
}
/* Variant of the private constructor so that the given charset name
* can be verified before evaluating the OutputStream argument. Used
* by constructors creating a FileOutputStream that also take a
* charset name.
*/
private PrintStream(boolean autoFlush, Charset charset, OutputStream out)
throws UnsupportedEncodingException
{
this(autoFlush, out, charset);
}
/**
* Creates a new print stream. This stream will not flush automatically.
*
* @param out The output stream to which values and objects will be
* printed
*
* @see java.io.PrintWriter#PrintWriter(java.io.OutputStream)
*/
public PrintStream(OutputStream out) {
this(out, false);
}
/**
* Creates a new print stream.
*
* @param out The output stream to which values and objects will be
* printed
* @param autoFlush A boolean; if true, the output buffer will be flushed
* whenever a byte array is written, one of the
* <code>println</code> methods is invoked, or a newline
* character or byte (<code>'\n'</code>) is written
*
* @see java.io.PrintWriter#PrintWriter(java.io.OutputStream, boolean)
*/
public PrintStream(OutputStream out, boolean autoFlush) {
this(autoFlush, requireNonNull(out, "Null output stream"));
}
/**
* Creates a new print stream.
*
* @param out The output stream to which values and objects will be
* printed
* @param autoFlush A boolean; if true, the output buffer will be flushed
* whenever a byte array is written, one of the
* <code>println</code> methods is invoked, or a newline
* character or byte (<code>'\n'</code>) is written
* @param encoding The name of a supported
* <a href="../lang/package-summary.html#charenc">
* character encoding</a>
*
* @throws UnsupportedEncodingException
* If the named encoding is not supported
*
* @since 1.4
*/
public PrintStream(OutputStream out, boolean autoFlush, String encoding)
throws UnsupportedEncodingException
{
this(autoFlush,
requireNonNull(out, "Null output stream"),
toCharset(encoding));
}
/**
* Creates a new print stream, without automatic line flushing, with the
* specified file name. This convenience constructor creates
* the necessary intermediate {@link java.io.OutputStreamWriter
* OutputStreamWriter}, which will encode characters using the
* {@linkplain java.nio.charset.Charset#defaultCharset() default charset}
* for this instance of the Java virtual machine.
*
* @param 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
*
* @throws SecurityException
* If a security manager is present and {@link
* SecurityManager#checkWrite checkWrite(fileName)} denies write
* access to the file
*
* @since 1.5
*/
public PrintStream(String fileName) throws FileNotFoundException {
this(false, new FileOutputStream(fileName));
}
/**
* Creates a new print stream, without automatic line flushing, with the
* specified file name and charset. This convenience constructor creates
* the necessary intermediate {@link java.io.OutputStreamWriter
* OutputStreamWriter}, which will encode characters using the provided
* charset.
*
* @param 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.
*
* @param csn
* The name of a supported {@linkplain java.nio.charset.Charset
* 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
*
* @throws SecurityException
* If a security manager is present and {@link
* SecurityManager#checkWrite checkWrite(fileName)} denies write
* access to the file
*
* @throws UnsupportedEncodingException
* If the named charset is not supported
*
* @since 1.5
*/
public PrintStream(String fileName, String csn)
throws FileNotFoundException, UnsupportedEncodingException
{
// ensure charset is checked before the file is opened
this(false, toCharset(csn), new FileOutputStream(fileName));
}
/**
* Creates a new print stream, without automatic line flushing, with the
* specified file. This convenience constructor creates the necessary
* intermediate {@link java.io.OutputStreamWriter OutputStreamWriter},
* which will encode characters using the {@linkplain
* java.nio.charset.Charset#defaultCharset() default charset} for this
* instance of the Java virtual machine.
*
* @param 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
*
* @throws SecurityException
* If a security manager is present and {@link
* SecurityManager#checkWrite checkWrite(file.getPath())}
* denies write access to the file
*
* @since 1.5
*/
public PrintStream(File file) throws FileNotFoundException {
this(false, new FileOutputStream(file));
}
/**
* Creates a new print stream, without automatic line flushing, with the
* specified file and charset. This convenience constructor creates
* the necessary intermediate {@link java.io.OutputStreamWriter
* OutputStreamWriter}, which will encode characters using the provided
* charset.
*
* @param 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.
*
* @param csn
* The name of a supported {@linkplain java.nio.charset.Charset
* 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
*
* @throws SecurityException
* If a security manager is present and {@link
* SecurityManager#checkWrite checkWrite(file.getPath())}
* denies write access to the file
*
* @throws UnsupportedEncodingException
* If the named charset is not supported
*
* @since 1.5
*/
public PrintStream(File file, String csn)
throws FileNotFoundException, UnsupportedEncodingException
{
// ensure charset is checked before the file is opened
this(false, toCharset(csn), new FileOutputStream(file));
}
/** Check to make sure that the stream has not been closed */
private void ensureOpen() throws IOException {
if (out == null)
throw new IOException("Stream closed");
}
/**
* Flushes the stream. This is done by writing any buffered output bytes to
* the underlying output stream and then flushing that stream.
*
* @see java.io.OutputStream#flush()
*/
public void flush() {
synchronized (this) {
try {
ensureOpen();
out.flush();
}
catch (IOException x) {
trouble = true;
}
}
}
private boolean closing = false; /* To avoid recursive closing */
/**
* Closes the stream. This is done by flushing the stream and then closing
* the underlying output stream.
*
* @see java.io.OutputStream#close()
*/
public void close() {
synchronized (this) {
if (! closing) {
closing = true;
try {
textOut.close();
out.close();
}
catch (IOException x) {
trouble = true;
}
textOut = null;
charOut = null;
out = null;
}
}
}
/**
* Flushes the stream and checks its error state. The internal error state
* is set to <code>true</code> when the underlying output stream throws an
* <code>IOException</code> other than <code>InterruptedIOException</code>,
* and when the <code>setError</code> method is invoked. If an operation
* on the underlying output stream throws an
* <code>InterruptedIOException</code>, then the <code>PrintStream</code>
* converts the exception back into an interrupt by doing:
* <pre>
* Thread.currentThread().interrupt();
* </pre>
* or the equivalent.
*
* @return <code>true</code> if and only if this stream has encountered an
* <code>IOException</code> other than
* <code>InterruptedIOException</code>, or the
* <code>setError</code> method has been invoked
*/
public boolean checkError() {
if (out != null)
flush();
if (out instanceof java.io.PrintStream) {
PrintStream ps = (PrintStream) out;
return ps.checkError();
}
return trouble;
}
/**
* Sets the error state of the stream to <code>true</code>.
*
* <p> This method will cause subsequent invocations of {@link
* #checkError()} to return <tt>true</tt> until {@link
* #clearError()} is invoked.
*
* @since JDK1.1
*/
protected void setError() {
trouble = true;
}
/**
* Clears the internal error state of this stream.
*
* <p> This method will cause subsequent invocations of {@link
* #checkError()} to return <tt>false</tt> until another write
* operation fails and invokes {@link #setError()}.
*
* @since 1.6
*/
protected void clearError() {
trouble = false;
}
/*
* Exception-catching, synchronized output operations,
* which also implement the write() methods of OutputStream
*/
/**
* Writes the specified byte to this stream. If the byte is a newline and
* automatic flushing is enabled then the <code>flush</code> method will be
* invoked.
*
* <p> Note that the byte is written as given; to write a character that
* will be translated according to the platform's default character
* encoding, use the <code>print(char)</code> or <code>println(char)</code>
* methods.
*
* @param b The byte to be written
* @see #print(char)
* @see #println(char)
*/
public void write(int b) {
try {
synchronized (this) {
ensureOpen();
out.write(b);
if ((b == '\n') && autoFlush)
out.flush();
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
/**
* Writes <code>len</code> bytes from the specified byte array starting at
* offset <code>off</code> to this stream. If automatic flushing is
* enabled then the <code>flush</code> method will be invoked.
*
* <p> Note that the bytes will be written as given; to write characters
* that will be translated according to the platform's default character
* encoding, use the <code>print(char)</code> or <code>println(char)</code>
* methods.
*
* @param buf A byte array
* @param off Offset from which to start taking bytes
* @param len Number of bytes to write
*/
public void write(byte buf[], int off, int len) {
try {
synchronized (this) {
ensureOpen();
out.write(buf, off, len);
if (autoFlush)
out.flush();
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
/*
* The following private methods on the text- and character-output streams
* always flush the stream buffers, so that writes to the underlying byte
* stream occur as promptly as with the original PrintStream.
*/
private void write(char buf[]) {
try {
synchronized (this) {
ensureOpen();
textOut.write(buf);
textOut.flushBuffer();
charOut.flushBuffer();
if (autoFlush) {
for (int i = 0; i < buf.length; i++)
if (buf[i] == '\n')
out.flush();
}
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
private void write(String s) {
try {
synchronized (this) {
ensureOpen();
textOut.write(s);
textOut.flushBuffer();
charOut.flushBuffer();
if (autoFlush && (s.indexOf('\n') >= 0))
out.flush();
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
private void newLine() {
try {
synchronized (this) {
ensureOpen();
textOut.newLine();
textOut.flushBuffer();
charOut.flushBuffer();
if (autoFlush)
out.flush();
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
/* Methods that do not terminate lines */
/**
* Prints a boolean value. The string produced by <code>{@link
* java.lang.String#valueOf(boolean)}</code> is translated into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param b The <code>boolean</code> to be printed
*/
public void print(boolean b) {
write(b ? "true" : "false");
}
/**
* Prints a character. The character is translated into one or more bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param c The <code>char</code> to be printed
*/
public void print(char c) {
write(String.valueOf(c));
}
/**
* Prints an integer. The string produced by <code>{@link
* java.lang.String#valueOf(int)}</code> is translated into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param i The <code>int</code> to be printed
* @see java.lang.Integer#toString(int)
*/
public void print(int i) {
write(String.valueOf(i));
}
/**
* Prints a long integer. The string produced by <code>{@link
* java.lang.String#valueOf(long)}</code> is translated into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param l The <code>long</code> to be printed
* @see java.lang.Long#toString(long)
*/
public void print(long l) {
write(String.valueOf(l));
}
/**
* Prints a floating-point number. The string produced by <code>{@link
* java.lang.String#valueOf(float)}</code> is translated into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param f The <code>float</code> to be printed
* @see java.lang.Float#toString(float)
*/
public void print(float f) {
write(String.valueOf(f));
}
/**
* Prints a double-precision floating-point number. The string produced by
* <code>{@link java.lang.String#valueOf(double)}</code> is translated into
* bytes according to the platform's default character encoding, and these
* bytes are written in exactly the manner of the <code>{@link
* #write(int)}</code> method.
*
* @param d The <code>double</code> to be printed
* @see java.lang.Double#toString(double)
*/
public void print(double d) {
write(String.valueOf(d));
}
/**
* Prints an array of characters. The characters are converted into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param s The array of chars to be printed
*
* @throws NullPointerException If <code>s</code> is <code>null</code>
*/
public void print(char s[]) {
write(s);
}
/**
* Prints a string. If the argument is <code>null</code> then the string
* <code>"null"</code> is printed. Otherwise, the string's characters are
* converted into bytes according to the platform's default character
* encoding, and these bytes are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param s The <code>String</code> to be printed
*/
public void print(String s) {
if (s == null) {
s = "null";
}
write(s);
}
/**
* Prints an object. The string produced by the <code>{@link
* java.lang.String#valueOf(Object)}</code> method is translated into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param obj The <code>Object</code> to be printed
* @see java.lang.Object#toString()
*/
public void print(Object obj) {
write(String.valueOf(obj));
}
/* Methods that do terminate lines */
/**
* Terminates the current line by writing the line separator string. The
* line separator string is defined by the system property
* <code>line.separator</code>, and is not necessarily a single newline
* character (<code>'\n'</code>).
*/
public void println() {
newLine();
}
/**
* Prints a boolean and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(boolean)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>boolean</code> to be printed
*/
public void println(boolean x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints a character and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(char)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>char</code> to be printed.
*/
public void println(char x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints an integer and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(int)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>int</code> to be printed.
*/
public void println(int x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints a long and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(long)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x a The <code>long</code> to be printed.
*/
public void println(long x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints a float and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(float)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>float</code> to be printed.
*/
public void println(float x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints a double and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(double)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>double</code> to be printed.
*/
public void println(double x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints an array of characters and then terminate the line. This method
* behaves as though it invokes <code>{@link #print(char[])}</code> and
* then <code>{@link #println()}</code>.
*
* @param x an array of chars to print.
*/
public void println(char x[]) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints a String and then terminate the line. This method behaves as
* though it invokes <code>{@link #print(String)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>String</code> to be printed.
*/
public void println(String x) {
synchronized (this) {
print(x);
newLine();
}
}
/**
* Prints an Object and then terminate the line. This method calls
* at first String.valueOf(x) to get the printed object's string value,
* then behaves as
* though it invokes <code>{@link #print(String)}</code> and then
* <code>{@link #println()}</code>.
*
* @param x The <code>Object</code> to be printed.
*/
public void println(Object x) {
String s = String.valueOf(x);
synchronized (this) {
print(s);
newLine();
}
}
/**
* A convenience method to write a formatted string to this output stream
* using the specified format string and arguments.
*
* <p> An invocation of this method of the form <tt>out.printf(format,
* args)</tt> behaves in exactly the same way as the invocation
*
* <pre>
* out.format(format, args) </pre>
*
* @param format
* A format string as described in <a
* href="../util/Formatter.html#syntax">Format string syntax</a>
*
* @param 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
* <cite>The Java™ Virtual Machine Specification</cite>.
* The behaviour on a
* <tt>null</tt> argument depends on the <a
* href="../util/Formatter.html#syntax">conversion</a>.
*
* @throws java.util.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 <a
* href="../util/Formatter.html#detail">Details</a> section of the
* formatter class specification.
*
* @throws NullPointerException
* If the <tt>format</tt> is <tt>null</tt>
*
* @return This output stream
*
* @since 1.5
*/
public PrintStream printf(String format, Object ... args) {
return format(format, args);
}
/**
* A convenience method to write a formatted string to this output stream
* using the specified format string and arguments.
*
* <p> An invocation of this method of the form <tt>out.printf(l, format,
* args)</tt> behaves in exactly the same way as the invocation
*
* <pre>
* out.format(l, format, args) </pre>
*
* @param l
* The {@linkplain java.util.Locale locale} to apply during
* formatting. If <tt>l</tt> is <tt>null</tt> then no localization
* is applied.
*
* @param format
* A format string as described in <a
* href="../util/Formatter.html#syntax">Format string syntax</a>
*
* @param 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
* <cite>The Java™ Virtual Machine Specification</cite>.
* The behaviour on a
* <tt>null</tt> argument depends on the <a
* href="../util/Formatter.html#syntax">conversion</a>.
*
* @throws java.util.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 <a
* href="../util/Formatter.html#detail">Details</a> section of the
* formatter class specification.
*
* @throws NullPointerException
* If the <tt>format</tt> is <tt>null</tt>
*
* @return This output stream
*
* @since 1.5
*/
public PrintStream printf(Locale l, String format, Object ... args) {
return format(l, format, args);
}
/**
* Writes a formatted string to this output stream using the specified
* format string and arguments.
*
* <p> The locale always used is the one returned by {@link
* java.util.Locale#getDefault() Locale.getDefault()}, regardless of any
* previous invocations of other formatting methods on this object.
*
* @param format
* A format string as described in <a
* href="../util/Formatter.html#syntax">Format string syntax</a>
*
* @param 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
* <cite>The Java™ Virtual Machine Specification</cite>.
* The behaviour on a
* <tt>null</tt> argument depends on the <a
* href="../util/Formatter.html#syntax">conversion</a>.
*
* @throws java.util.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 <a
* href="../util/Formatter.html#detail">Details</a> section of the
* formatter class specification.
*
* @throws NullPointerException
* If the <tt>format</tt> is <tt>null</tt>
*
* @return This output stream
*
* @since 1.5
*/
public PrintStream format(String format, Object ... args) {
try {
synchronized (this) {
ensureOpen();
if ((formatter == null)
|| (formatter.locale() != Locale.getDefault()))
formatter = new Formatter((Appendable) this);
formatter.format(Locale.getDefault(), format, args);
}
} catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
} catch (IOException x) {
trouble = true;
}
return this;
}
/**
* Writes a formatted string to this output stream using the specified
* format string and arguments.
*
* @param l
* The {@linkplain java.util.Locale locale} to apply during
* formatting. If <tt>l</tt> is <tt>null</tt> then no localization
* is applied.
*
* @param format
* A format string as described in <a
* href="../util/Formatter.html#syntax">Format string syntax</a>
*
* @param 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
* <cite>The Java™ Virtual Machine Specification</cite>.
* The behaviour on a
* <tt>null</tt> argument depends on the <a
* href="../util/Formatter.html#syntax">conversion</a>.
*
* @throws java.util.IllegalFormatException
* If a format string contains an illegal syntax, a format
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