java.text.DecimalFormat#setNegativePrefix ( )源码实例Demo

public static <T extends Number> byte[] convertSignedNumericToArray(int length, T value, int precision )
{

       // Pattern for fractional part
	char[] arrFractional = new char[precision];
	Arrays.fill(arrFractional, '0');

	// Pattern for mantissa
	char[] arrMantissa = new char[length - 1 - precision ];
	Arrays.fill(arrMantissa, '0');

	String patternDesired = String.format( "%s.%s", new String(arrMantissa), new String(arrFractional));
	DecimalFormat formatter = new DecimalFormat(patternDesired );
	formatter.setPositivePrefix("+");
	formatter.setNegativePrefix("-");
	formatter.setGroupingUsed(false);
	String formattedValue = formatter.format(value);
	DecimalFormatSymbols decimalFormatSymbol = formatter.getDecimalFormatSymbols();
	formattedValue = formattedValue.replace(String.valueOf(decimalFormatSymbol.getDecimalSeparator()), "");
       return formattedValue.getBytes(charsetISO_8859);
}
 

public static <T extends Number> byte[] convertUnsignedNumericToArray(int length, T value, int precision )
{

       // Pattern for fractional part
	char[] arrFractional = new char[precision];
	Arrays.fill(arrFractional, '0');

	// Pattern for mantissa
	char[] arrMantissa = new char[length - precision ];
	Arrays.fill(arrMantissa, '0');

	String patternDesired = String.format( "%s.%s", new String(arrMantissa), new String(arrFractional));
	DecimalFormat formatter = new DecimalFormat(patternDesired );
	formatter.setPositivePrefix("");
	formatter.setNegativePrefix("");
	formatter.setGroupingUsed(false);
	String formattedValue = formatter.format(value);
	DecimalFormatSymbols decimalFormatSymbol = formatter.getDecimalFormatSymbols();
	formattedValue = formattedValue.replace(String.valueOf(decimalFormatSymbol.getDecimalSeparator()), "");
       return formattedValue.getBytes(charsetISO_8859);
}
 

public FloatingPointFormat( int w, int d ) {
  width = w;
  decimal = d;
  nf = new DecimalFormat( pattern(w, d) );
  nf.setPositivePrefix(" ");
  nf.setNegativePrefix("-");
}
 

public ExponentialFormat( int digits, int exp, boolean sign, 
	    boolean trailing ) {
  this.digits = digits;
  this.exp = exp;
  this.sign = sign;
  this.trailing = trailing;
  nf = new DecimalFormat( pattern() );
  nf.setPositivePrefix("+");
  nf.setNegativePrefix("-");
}
 

/**
   * Constructor. Creates a FloatingPointFormat with the given values width and decimal size.
   * @param w width given.
   * @param d decimal size given.
   */
  public FloatingPointFormat( int w, int d ) {
  width = w;
  decimal = d;
  nf = new DecimalFormat( pattern(w, d) );
  nf.setPositivePrefix(" ");
  nf.setNegativePrefix("-");
}
 

/**
   ** Constructor. Creates a ExponentialFormat with the given arguments.
   * @param digits given base size.
   * @param exp given exponent size.
   * @param sign given sign flag.
   * @param trailing given trailing flag.
   */
  public ExponentialFormat( int digits, int exp, boolean sign, 
	    boolean trailing ) {
  this.digits = digits;
  this.exp = exp;
  this.sign = sign;
  this.trailing = trailing;
  nf = new DecimalFormat( pattern() );
  nf.setPositivePrefix("+");
  nf.setNegativePrefix("-");
}
 

public void test_setNegativePrefix() throws Exception {
    DecimalFormat format = new DecimalFormat();
    assertEquals("-", format.getNegativePrefix());

    format.setNegativePrefix("NegPrf");
    assertEquals("NegPrf", format.getNegativePrefix());
    assertTrue(format.parse("NegPrf123.45").doubleValue() == -123.45);
    format.setNegativePrefix("");
    assertEquals("", format.getNegativePrefix());

    format.setNegativePrefix(null);
    assertNull(format.getNegativePrefix());
}
 

public Chart2ValueFormatter() {
    mFormat = new DecimalFormat("###,###,##0.0"); // use one decimal
    mFormat.setNegativePrefix("");
}
 

public void test_getNegativePrefix() {
    DecimalFormat df = new DecimalFormat();
    df.setNegativePrefix("--");
    assertTrue("Incorrect negative prefix", df.getNegativePrefix().equals("--"));
}