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Chapter 16 The java.text Package |
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Chapter 16 The java.text Package |
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java.text.DecimalFormat
java.text.NumberFormat
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New as of JDK 1.1
The DecimalFormat class is a concrete subclass of NumberFormat that formats and parses numbers using a formatting pattern. Typically, you do not need to instantiate DecimalFormat yourself. Instead, the factory methods of NumberFormat return instances of DecimalFormat that are appropriate for particular locales.
However, if you need a specialized number format, you can instantiate your own DecimalFormat using a pattern string. You can also modify the formatting pattern of an existing DecimalFormat object using the applyPattern() method. A pattern string has the following form:
positive-pattern[;negative-pattern]
If the negative pattern is omitted, negative numbers are formatted using the positive pattern with a - character prepended to the result. Each pattern has the following form:
[prefix]integer[.fraction][suffix]
The following symbols are significant in the pattern string.
| Symbol | Description |
|---|---|
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0 |
A digit |
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# |
A digit where 0 is not shown |
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. |
A placeholder for a decimal separator |
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, |
A placeholder for a grouping separator |
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; |
The format separator |
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- |
The default negative prefix |
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% |
Divides value by 100 and shows as a percentage |
Any characters other than these special characters can appear in the prefix or the suffix. A single quote can be used to escape a special character, if you need to use one of these symbols in a prefix or a suffix.
For example, the pattern string for U.S. currency values is:
$#,##0.00;($#,##0.00)
This indicates that a $ character is prepended to all formatted values. The grouping separator character , is inserted every three digits. Exactly two digits after the decimal place are always shown. Negative values are shown in parentheses. Thus, the value -1234.56 produces output like:
($1,234.56)
Internally, the DecimalFormat class uses a DecimalFormatSymbols object to get the numerical strings that are appropriate for a particular locale. If you want to modify these strings, you can get the DecimalFormatSymbols object by calling getDecimalFormatSymbols().
public class java.text.DecimalFormat extends java.text.NumberFormat {
// Constructors
public DecimalFormat();
public DecimalFormat(String pattern);
public DecimalFormat(String pattern, DecimalFormatSymbols symbols);
// Instance Methods
public void applyLocalizedPattern(String pattern);
public void applyPattern(String pattern);
public Object clone();
public boolean equals(Object obj);
public StringBuffer format(double number, StringBuffer result,
FieldPosition fieldPosition);
public StringBuffer format(long number, StringBuffer result,
FieldPosition fieldPosition);
public DecimalFormatSymbols getDecimalFormatSymbols();
public int getGroupingSize();
public int getMultiplier();
public String getNegativePrefix();
public String getNegativeSuffix();
public String getPositivePrefix();
public String getPositiveSuffix();
public int hashCode();
public boolean isDecimalSeparatorAlwaysShown();
public Number parse(String text, ParsePosition status);
public void setDecimalFormatSymbols(DecimalFormatSymbols newSymbols);
public void setDecimalSeparatorAlwaysShown(boolean newValue);
public void setGroupingSize(int newValue);
public void setMultiplier(int newValue);
public void setNegativePrefix(String newValue);
public void setNegativeSuffix(String newValue);
public void setPositivePrefix(String newValue);
public void setPositiveSuffix(String newValue);
public String toLocalizedPattern();
public String toPattern();
}
This constructor creates a DecimalFormat that uses the default formatting pattern and DecimalFormatSymbols that are appropriate for the default locale.
The pattern string.
This constructor creates a DecimalFormat that uses the given formatting pattern and a DecimalFormatSymbols that is appropriate for the default locale.
The pattern string.
The DecimalFormatSymbols to use.
This constructor creates a DecimalFormat that uses the given formatting pattern and DecimalFormatSymbols object.
The pattern string.
This method tells this DecimalFormat to use the given formatting pattern to format and parse numbers. The pattern string is assumed to have been localized to the DecimalFormatSymbols object this DecimalFormat uses.
The pattern string.
This method tells this DecimalFormat to use the given formatting pattern to format and parse numbers. The pattern string is localized to the DecimalFormatSymbols object this DecimalFormat uses.
A copy of this DecimalFormat.
NumberFormat.clone()
This method creates a copy of this DecimalFormat and then returns it.
The object to be compared with this object.
true if the objects are equal; false if they are not.
NumberFormat.equals()
This method returns true if obj is an instance of DecimalFormat and is equivalent to this DecimalFormat.
public StringBuffer format(double number, StringBuffer result, FieldPosition fieldPosition)
The double value to be formatted.
A StringBuffer on which to append the formatted information.
A number field.
The given buffer result with the formatted representation of the number appended to it.
NumberFormat.format(double, StringBuffer, FieldPosition)
This method formats the given number and appends the result to the given StringBuffer. If fieldPosition refers to one of the number fields, its beginning and ending indices are filled with the beginning and ending positions of the given field in the resulting formatted string.
public StringBuffer format(long number, StringBuffer result, FieldPosition fieldPosition)
The long value to be formatted.
A StringBuffer on which to append the formatted information.
A number field.
The given buffer result with the formatted representation of the number appended to it.
NumberFormat.format(double, StringBuffer, FieldPosition)
This method formats the given number and appends the result to the given StringBuffer. If fieldPosition refers to one of the number fields, its beginning and ending indices are filled with the beginning and ending positions of the given field in the resulting formatted string.
The DecimalFormatSymbols object used by this DecimalFormat.
This method returns the DecimalFormatSymbols object that this DecimalFormat uses internally.
The grouping size of this DecimalFormat.
This method returns the grouping size of this DecimalFormat. The grouping size is the number of digits between grouping separators in the integer portion of a number. For example, in the number 1,234.56, the grouping size is 3 (and the grouping symbol is ",").
The multiplier of this DecimalFormat.
This method returns the multiplier of this DecimalFormat. The multiplier is used to adjust a number before it is formatted or after it is parsed. For example, a percent format has a multiplier of 100 and a suffix of `%'. Thus, a value of .42 could be formatted as 42%.
The string that is prepended to negative values.
This method returns the prefix string for negative numbers.
The string that is appended to negative values.
This method returns the suffix string for negative numbers.
The string that is prepended to positive values.
This method returns the prefix string for positive numbers.
The string that is appended to positive values.
This method returns the suffix string for positive numbers.
A hashcode for this object.
NumberFormat.hashCode()
This method returns a hashcode for this DecimalFormat.
A boolean value that indicates whether or not the decimal separator symbol is always shown.
This method returns true if this DecimalFormat always shows the decimal separator. The method returns false if the decimal separator is only shown if there is a fractional portion of the number being formatted.
The string to be parsed.
A ParsePosition object that specifies a position in the string.
The Number object represented by the text starting at the given position.
NumberFormat.parse(String, ParsePosition)
This method parses a number from the given string, starting from the given position. After the string has been parsed, the given ParsePosition object is updated so that its index is after the parsed text.
public void setDecimalFormatSymbols( DecimalFormatSymbols newSymbols)
The new DecimalFormatSymbols object to use.
This method sets the DecimalFormatSymbols object that this DecimalFormat uses internally.
The new decimal separator value.
This method specifies whether or not the decimal separator symbol is always shown in formatted numbers. If newValue is false, the separator is only shown for numbers that have a fractional part. Otherwise, the separator is always shown.
The new grouping size.
This method sets the grouping size of this DecimalFormat. The grouping size is the number of digits between grouping separators in the integer portion of a number. For example, in the number 1,234.56, the grouping size is 3 (and the grouping symbol is ",").
The new multiplier.
This method sets the multiplier of this DecimalFormat. The multiplier is used to adjust a number before it is formatted or after it is parsed. For example, a percent format has a multiplier of 100 and a suffix of %. Thus, a value of .42 could be formatted as 42%.
The new prefix.
This method sets the prefix string for negative values.
The new suffix.
This method sets the suffix string for negative values.
The new prefix.
This method sets the prefix string for positive values.
The new suffix.
This method sets the suffix string for positive values.
The pattern string of this DecimalFormat.
This method returns the pattern string of this DecimalFormat, localized with the DecimalFormatSymbols object of this DecimalFormat.
The pattern string of this DecimalFormat.
This method returns the pattern string of this DecimalFormat.
| Method | Inherited From | Method | Inherited From |
|---|---|---|---|
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finalize() |
Object |
format(double) |
NumberFormat |
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format(long) |
NumberFormat |
format(Object, StringBuffer, FieldPosition) |
NumberFormat |
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getClass() |
Object |
getMaximumFractionDigits() |
NumberFormat |
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getMaximumIntegerDigits() |
NumberFormat |
getMinimumFractionDigits() |
NumberFormat |
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getMinimumIntegerDigits() |
NumberFormat |
isGroupingUsed() |
NumberFormat |
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isParseIntegerOnly() |
NumberFormat |
notify() |
Object |
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notifyAll() |
Object |
parse(String) |
NumberFormat |
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parseObject(String) |
Format |
parseObject(String, ParsePosition) |
NumberFormat |
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setGroupingUsed(boolean) |
NumberFormat |
setMaximumFractionDigits(int) |
NumberFormat |
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setMaximumIntegerDigits(int) |
NumberFormat |
setMinimumFractionDigits(int) |
NumberFormat |
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setMinimumIntegerDigits(int) |
NumberFormat |
setParseIntegerOnly(boolean) |
NumberFormat |
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toString() |
Object |
wait() |
Object |
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wait(long) |
Object |
wait(long, int) |
Object |
DecimalFormatSymbols, FieldPosition, Number, NumberFormat, ParsePosition, String, StringBuffer
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| DateFormatSymbols |  |
DecimalFormatSymbols |
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