MessageFormat Class
Definition
Important
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MessageFormat provides a means to produce concatenated
messages in a language-neutral way.
[Android.Runtime.Register("java/text/MessageFormat", DoNotGenerateAcw=true)]
public class MessageFormat : Java.Text._Format[<Android.Runtime.Register("java/text/MessageFormat", DoNotGenerateAcw=true)>]
type MessageFormat = class
inherit _Format- Inheritance
- Attributes
Remarks
MessageFormat provides a means to produce concatenated messages in a language-neutral way. Use this to construct messages displayed for end users.
MessageFormat takes a set of objects, formats them, then inserts the formatted strings into the pattern at the appropriate places.
<strong>Note:</strong> MessageFormat differs from the other Format classes in that you create a MessageFormat object with one of its constructors (not with a getInstance style factory method). The factory methods aren't necessary because MessageFormat itself doesn't implement locale specific behavior. Any locale specific behavior is defined by the pattern that you provide as well as the subformats used for inserted arguments.
<h2>"patterns">Patterns and Their Interpretation</h2>
MessageFormat uses patterns of the following form: <blockquote>
<i>MessageFormatPattern:</i>
<i>String</i>
<i>MessageFormatPattern</i> <i>FormatElement</i> <i>String</i>
<i>FormatElement:</i>
{ <i>ArgumentIndex</i> }
{ <i>ArgumentIndex</i> , <i>FormatType</i> }
{ <i>ArgumentIndex</i> , <i>FormatType</i> , <i>FormatStyle</i> }
<i>FormatType: one of </i>
number date time choice
<i>FormatStyle:</i>
short
medium
long
full
integer
currency
percent
<i>SubformatPattern</i>
</blockquote>
Within a String, a pair of single quotes can be used to quote any arbitrary characters except single quotes. For example, pattern string "'{0}'" represents string "{0}", not a FormatElement. A single quote itself must be represented by doubled single quotes '' throughout a String. For example, pattern string "'{''}'" is interpreted as a sequence of '{ (start of quoting and a left curly brace), '' (a single quote), and }' (a right curly brace and end of quoting), <em>not</em> '{' and '}' (quoted left and right curly braces): representing string "{'}", <em>not</em> "{}".
A SubformatPattern is interpreted by its corresponding subformat, and subformat-dependent pattern rules apply. For example, pattern string "{1,number,<u>$'#',##</u>}" (SubformatPattern with underline) will produce a number format with the pound-sign quoted, with a result such as: "$#31,45". Refer to each Format subclass documentation for details.
Any unmatched quote is treated as closed at the end of the given pattern. For example, pattern string "'{0"} is treated as pattern "'{0'"}.
Any curly braces within an unquoted pattern must be balanced. For example, "ab {0} de" and "ab '}' de" are valid patterns, but "ab {0'}' de", "ab } de" and "''{''" are not.
<dl><dt><b>Warning:</b><dd>The rules for using quotes within message format patterns unfortunately have shown to be somewhat confusing. In particular, it isn't always obvious to localizers whether single quotes need to be doubled or not. Make sure to inform localizers about the rules, and tell them (for example, by using comments in resource bundle source files) which strings will be processed by MessageFormat. Note that localizers may need to use single quotes in translated strings where the original version doesn't have them. </dl>
The ArgumentIndex value is a non-negative integer written using the digits '0' through '9', and represents an index into the arguments array passed to the format methods or the result array returned by the parse methods.
The FormatType and FormatStyle values are used to create a Format instance for the format element. The following table shows how the values map to Format instances. Combinations not shown in the table are illegal. A SubformatPattern must be a valid pattern string for the Format subclass used.
<table class="plain"> <caption style="display:none">Shows how FormatType and FormatStyle values map to Format instances</caption> <thead> <tr> <th scope="col" class="TableHeadingColor">FormatType <th scope="col" class="TableHeadingColor">FormatStyle <th scope="col" class="TableHeadingColor">Subformat Created </thead> <tbody> <tr> <th scope="row" style="text-weight: normal">(none)<th scope="row" style="text-weight: normal">(none)<td>null<tr> <th scope="row" style="text-weight: normal" rowspan=5>number<th scope="row" style="text-weight: normal">(none)<td>NumberFormat#getInstance(Locale) NumberFormat.getInstance(getLocale())<tr> <th scope="row" style="text-weight: normal">integer<td>NumberFormat#getIntegerInstance(Locale) NumberFormat.getIntegerInstance(getLocale())<tr> <th scope="row" style="text-weight: normal">currency<td>NumberFormat#getCurrencyInstance(Locale) NumberFormat.getCurrencyInstance(getLocale())<tr> <th scope="row" style="text-weight: normal">percent<td>NumberFormat#getPercentInstance(Locale) NumberFormat.getPercentInstance(getLocale())<tr> <th scope="row" style="text-weight: normal">SubformatPattern<td>newDecimalFormat#DecimalFormat(String,DecimalFormatSymbols) DecimalFormat(subformatPattern,DecimalFormatSymbols#getInstance(Locale) DecimalFormatSymbols.getInstance(getLocale()))<tr> <th scope="row" style="text-weight: normal" rowspan=6>date<th scope="row" style="text-weight: normal">(none)<td>DateFormat#getDateInstance(int,Locale) DateFormat.getDateInstance(DateFormat#DEFAULT, getLocale())<tr> <th scope="row" style="text-weight: normal">short<td>DateFormat#getDateInstance(int,Locale) DateFormat.getDateInstance(DateFormat#SHORT, getLocale())<tr> <th scope="row" style="text-weight: normal">medium<td>DateFormat#getDateInstance(int,Locale) DateFormat.getDateInstance(DateFormat#DEFAULT, getLocale())<tr> <th scope="row" style="text-weight: normal">long<td>DateFormat#getDateInstance(int,Locale) DateFormat.getDateInstance(DateFormat#LONG, getLocale())<tr> <th scope="row" style="text-weight: normal">full<td>DateFormat#getDateInstance(int,Locale) DateFormat.getDateInstance(DateFormat#FULL, getLocale())<tr> <th scope="row" style="text-weight: normal">SubformatPattern<td>newSimpleDateFormat#SimpleDateFormat(String,Locale) SimpleDateFormat(subformatPattern, getLocale())<tr> <th scope="row" style="text-weight: normal" rowspan=6>time<th scope="row" style="text-weight: normal">(none)<td>DateFormat#getTimeInstance(int,Locale) DateFormat.getTimeInstance(DateFormat#DEFAULT, getLocale())<tr> <th scope="row" style="text-weight: normal">short<td>DateFormat#getTimeInstance(int,Locale) DateFormat.getTimeInstance(DateFormat#SHORT, getLocale())<tr> <th scope="row" style="text-weight: normal">medium<td>DateFormat#getTimeInstance(int,Locale) DateFormat.getTimeInstance(DateFormat#DEFAULT, getLocale())<tr> <th scope="row" style="text-weight: normal">long<td>DateFormat#getTimeInstance(int,Locale) DateFormat.getTimeInstance(DateFormat#LONG, getLocale())<tr> <th scope="row" style="text-weight: normal">full<td>DateFormat#getTimeInstance(int,Locale) DateFormat.getTimeInstance(DateFormat#FULL, getLocale())<tr> <th scope="row" style="text-weight: normal">SubformatPattern<td>newSimpleDateFormat#SimpleDateFormat(String,Locale) SimpleDateFormat(subformatPattern, getLocale())<tr> <th scope="row" style="text-weight: normal">choice<th scope="row" style="text-weight: normal">SubformatPattern<td>newChoiceFormat#ChoiceFormat(String) ChoiceFormat(subformatPattern)</tbody> </table>
<h3>Usage Information</h3>
Here are some examples of usage. In real internationalized programs, the message format pattern and other static strings will, of course, be obtained from resource bundles. Other parameters will be dynamically determined at runtime.
The first example uses the static method MessageFormat.format, which internally creates a MessageFormat for one-time use: <blockquote>
int planet = 7;
String event = "a disturbance in the Force";
String result = MessageFormat.format(
"At {1,time} on {1,date}, there was {2} on planet {0,number,integer}.",
planet, new Date(), event);
</blockquote> The output is: <blockquote>
At 12:30 PM on Jul 3, 2053, there was a disturbance in the Force on planet 7.
</blockquote>
The following example creates a MessageFormat instance that can be used repeatedly: <blockquote>
int fileCount = 1273;
String diskName = "MyDisk";
Object[] testArgs = {new Long(fileCount), diskName};
MessageFormat form = new MessageFormat(
"The disk \"{1}\" contains {0} file(s).");
System.out.println(form.format(testArgs));
</blockquote> The output with different values for fileCount: <blockquote>
The disk "MyDisk" contains 0 file(s).
The disk "MyDisk" contains 1 file(s).
The disk "MyDisk" contains 1,273 file(s).
</blockquote>
For more sophisticated patterns, you can use a ChoiceFormat to produce correct forms for singular and plural: <blockquote>
MessageFormat form = new MessageFormat("The disk \"{1}\" contains {0}.");
double[] filelimits = {0,1,2};
String[] filepart = {"no files","one file","{0,number} files"};
ChoiceFormat fileform = new ChoiceFormat(filelimits, filepart);
form.setFormatByArgumentIndex(0, fileform);
int fileCount = 1273;
String diskName = "MyDisk";
Object[] testArgs = {new Long(fileCount), diskName};
System.out.println(form.format(testArgs));
</blockquote> The output with different values for fileCount: <blockquote>
The disk "MyDisk" contains no files.
The disk "MyDisk" contains one file.
The disk "MyDisk" contains 1,273 files.
</blockquote>
You can create the ChoiceFormat programmatically, as in the above example, or by using a pattern. See ChoiceFormat for more information. <blockquote>
{@code
form.applyPattern(
"There {0,choice,0#are no files|1#is one file|1<are {0,number,integer} files}.");
}
</blockquote>
<strong>Note:</strong> As we see above, the string produced by a ChoiceFormat in MessageFormat is treated as special; occurrences of '{' are used to indicate subformats, and cause recursion. If you create both a MessageFormat and ChoiceFormat programmatically (instead of using the string patterns), then be careful not to produce a format that recurses on itself, which will cause an infinite loop.
When a single argument is parsed more than once in the string, the last match will be the final result of the parsing. For example, <blockquote>
MessageFormat mf = new MessageFormat("{0,number,#.##}, {0,number,#.#}");
Object[] objs = {new Double(3.1415)};
String result = mf.format( objs );
// result now equals "3.14, 3.1"
objs = null;
objs = mf.parse(result, new ParsePosition(0));
// objs now equals {new Double(3.1)}
</blockquote>
Likewise, parsing with a MessageFormat object using patterns containing multiple occurrences of the same argument would return the last match. For example, <blockquote>
MessageFormat mf = new MessageFormat("{0}, {0}, {0}");
String forParsing = "x, y, z";
Object[] objs = mf.parse(forParsing, new ParsePosition(0));
// result now equals {new String("z")}
</blockquote>
<h3>"synchronization">Synchronization</h3>
Message formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.
Added in 1.1.
Java documentation for java.text.MessageFormat.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Constructors
| MessageFormat(IntPtr, JniHandleOwnership) |
A constructor used when creating managed representations of JNI objects; called by the runtime. |
| MessageFormat(String) |
Constructs a MessageFormat for the default
|
| MessageFormat(String, Locale) |
Constructs a MessageFormat for the specified locale and pattern. |
Properties
| Class |
Returns the runtime class of this |
| Handle |
The handle to the underlying Android instance. (Inherited from Object) |
| JniIdentityHashCode | (Inherited from Object) |
| JniPeerMembers | |
| Locale |
Gets the locale that's used when creating or comparing subformats. -or- Sets the locale to be used when creating or comparing subformats. |
| PeerReference | (Inherited from Object) |
| ThresholdClass |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
| ThresholdType |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
Methods
| ApplyPattern(String) |
Sets the pattern used by this message format. |
| Clone() |
Creates and returns a copy of this object. (Inherited from _Format) |
| Dispose() | (Inherited from Object) |
| Dispose(Boolean) | (Inherited from Object) |
| Equals(Object) |
Indicates whether some other object is "equal to" this one. (Inherited from Object) |
| Format(Object) |
Formats an object to produce a string. (Inherited from _Format) |
| Format(Object, StringBuffer, FieldPosition) |
Formats an array of objects and appends the |
| Format(Object[], StringBuffer, FieldPosition) |
Formats an array of objects and appends the |
| Format(String, Object[]) |
Formats an array of objects and appends the <code>MessageFormat</code>'s pattern, with format elements replaced by the formatted objects, to the provided <code>StringBuffer</code>. |
| FormatToCharacterIterator(Object) |
Formats an Object producing an |
| GetFormats() |
Gets the formats used for the format elements in the previously set pattern string. |
| GetFormatsByArgumentIndex() |
Gets the formats used for the values passed into
|
| GetHashCode() |
Returns a hash code value for the object. (Inherited from Object) |
| JavaFinalize() |
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object) |
| Notify() |
Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object) |
| NotifyAll() |
Wakes up all threads that are waiting on this object's monitor. (Inherited from Object) |
| Parse(String) |
Parses text from the beginning of the given string to produce an object array. |
| Parse(String, ParsePosition) |
Parses the string. |
| ParseObject(String) |
Parses text from the beginning of the given string to produce an object. (Inherited from _Format) |
| ParseObject(String, ParsePosition) |
Parses text from a string to produce an object array. |
| SetFormat(Int32, _Format) |
Sets the format to use for the format element with the given format element index within the previously set pattern string. |
| SetFormatByArgumentIndex(Int32, _Format) |
Sets the format to use for the format elements within the previously set pattern string that use the given argument index. |
| SetFormats(_Format[]) |
Sets the formats to use for the format elements in the previously set pattern string. |
| SetFormatsByArgumentIndex(_Format[]) |
Sets the formats to use for the values passed into
|
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. (Inherited from Object) |
| ToArray<T>() | (Inherited from Object) |
| ToPattern() |
Returns a pattern representing the current state of the message format. |
| ToString() |
Returns a string representation of the object. (Inherited from Object) |
| UnregisterFromRuntime() | (Inherited from Object) |
| Wait() |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object) |
| Wait(Int64) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| Wait(Int64, Int32) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
Explicit Interface Implementations
| IJavaPeerable.Disposed() | (Inherited from Object) |
| IJavaPeerable.DisposeUnlessReferenced() | (Inherited from Object) |
| IJavaPeerable.Finalized() | (Inherited from Object) |
| IJavaPeerable.JniManagedPeerState | (Inherited from Object) |
| IJavaPeerable.SetJniIdentityHashCode(Int32) | (Inherited from Object) |
| IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates) | (Inherited from Object) |
| IJavaPeerable.SetPeerReference(JniObjectReference) | (Inherited from Object) |
Extension Methods
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| GetJniTypeName(IJavaPeerable) | |