Integer represent primitive
- * int values.
- *
- * Additionally, this class provides various helper functions and variables
- * related to ints.
- *
- * @author Paul Fisher
- * @author John Keiser
- * @author Warren Levy
- * @since JDK 1.0
- */
-public final class Integer extends Number implements Comparable
-{
- // compatible with JDK 1.0.2+
- private static final long serialVersionUID = 1360826667806852920L;
-
- /**
- * The minimum value an int can represent is -2147483648.
- */
- public static final int MIN_VALUE = 0x80000000;
-
- /**
- * The maximum value an int can represent is 2147483647.
- */
- public static final int MAX_VALUE = 0x7fffffff;
-
- /**
- * The primitive type int is represented by this
- * Class object.
- */
- public static final Class TYPE = VMClassLoader.getPrimitiveClass ('I');
-
- /**
- * The immutable value of this Integer.
- */
- private final int value;
-
- /**
- * Create an Integer object representing the value of the
- * int argument.
- *
- * @param value the value to use
- */
- public Integer(int value)
- {
- this.value = value;
- }
-
- /**
- * Create an Integer object representing the value of the
- * argument after conversion to an int.
- *
- * @param s the string to convert.
- */
- public Integer(String s) throws NumberFormatException
- {
- value = parseInt(s, 10);
- }
-
- /**
- * Return a hashcode representing this Object.
- *
- * Integer's hash code is calculated by simply returning its
- * value.
- *
- * @return this Object's hash code.
- */
- public int hashCode()
- {
- return value;
- }
-
- /**
- * If the Object is not null, is an
- * instanceof Integer, and represents
- * the same primitive int value return
- * true. Otherwise false is returned.
- */
- public boolean equals(Object obj)
- {
- return obj instanceof Integer && value == ((Integer)obj).value;
- }
-
- /**
- * Get the specified system property as an Integer.
- *
- * The decode() method will be used to interpret the value of
- * the property.
- * @param nm the name of the system property
- * @return the system property as an Integer, or
- * null if the property is not found or cannot be
- * decoded as an Integer.
- * @see java.lang.System#getProperty(java.lang.String)
- * @see #decode(int)
- */
- public static Integer getInteger(String nm)
- {
- return getInteger(nm, null);
- }
-
- /**
- * Get the specified system property as an Integer, or use a
- * default int value if the property is not found or is not
- * decodable.
- *
- * The decode() method will be used to interpret the value of
- * the property.
- *
- * @param nm the name of the system property
- * @param val the default value to use if the property is not found or not
- * a number.
- * @return the system property as an Integer, or the default
- * value if the property is not found or cannot be decoded as an
- * Integer.
- * @see java.lang.System#getProperty(java.lang.String)
- * @see #decode(int)
- * @see #getInteger(java.lang.String,java.lang.Integer)
- */
- public static Integer getInteger(String nm, int val)
- {
- Integer result = getInteger(nm, null);
- return (result == null) ? new Integer(val) : result;
- }
-
- /**
- * Get the specified system property as an Integer, or use a
- * default Integer value if the property is not found or is
- * not decodable.
- *
- * The decode() method will be used to interpret the value of
- * the property.
- *
- * @param nm the name of the system property
- * @param val the default value to use if the property is not found or not
- * a number.
- * @return the system property as an Integer, or the default
- * value if the property is not found or cannot be decoded as an
- * Integer.
- * @see java.lang.System#getProperty(java.lang.String)
- * @see #decode(int)
- * @see #getInteger(java.lang.String,int)
- */
- public static Integer getInteger(String nm, Integer def)
- {
- if (nm == null || "".equals(nm))
- return def;
- nm = System.getProperty(nm);
- if (nm == null) return def;
- try
- {
- return decode(nm);
- }
- catch (NumberFormatException e)
- {
- return def;
- }
- }
-
- private static String toUnsignedString(int num, int exp)
- {
- // Use an array large enough for a binary number.
- int radix = 1 << exp;
- int mask = radix - 1;
- char[] buffer = new char[32];
- int i = 32;
- do
- {
- buffer[--i] = Character.forDigit(num & mask, radix);
- num = num >>> exp;
- }
- while (num != 0);
-
- return String.valueOf(buffer, i, 32-i);
- }
-
- /**
- * Converts the int to a String assuming it is
- * unsigned in base 16.
- * @param i the int to convert to String
- * @return the String representation of the argument.
- */
- public static String toHexString(int i)
- {
- return toUnsignedString(i, 4);
- }
-
- /**
- * Converts the int to a String assuming it is
- * unsigned in base 8.
- * @param i the int to convert to String
- * @return the String representation of the argument.
- */
- public static String toOctalString(int i)
- {
- return toUnsignedString(i, 3);
- }
-
- /**
- * Converts the int to a String assuming it is
- * unsigned in base 2.
- * @param i the int to convert to String
- * @return the String representation of the argument.
- */
- public static String toBinaryString(int i)
- {
- return toUnsignedString(i, 1);
- }
-
- /**
- * Converts the int to a String and assumes
- * a radix of 10.
- * @param i the int to convert to String
- * @return the String representation of the argument.
- */
- public static String toString(int i)
- {
- // This is tricky: in libgcj, String.valueOf(int) is a fast native
- // implementation. In Classpath it just calls back to
- // Integer.toString(int,int).
- return String.valueOf (i);
- }
-
- /**
- * Converts the Integer value to a String and
- * assumes a radix of 10.
- * @return the String representation of this Integer.
- */
- public String toString()
- {
- return toString (value);
- }
-
- /**
- * Converts the int to a String using
- * the specified radix (base).
- * @param i the int to convert to String.
- * @param radix the radix (base) to use in the conversion.
- * @return the String representation of the argument.
- */
- public static String toString(int num, int radix)
- {
- if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
- radix = 10;
-
- // For negative numbers, print out the absolute value w/ a leading '-'.
- // Use an array large enough for a binary number.
- char[] buffer = new char[33];
- int i = 33;
- boolean isNeg;
- if (num < 0)
- {
- isNeg = true;
- num = -(num);
-
- // When the value is MIN_VALUE, it overflows when made positive
- if (num < 0)
- {
- buffer[--i] = Character.forDigit(-(num + radix) % radix, radix);
- num = -(num / radix);
- }
- }
- else
- isNeg = false;
-
- do
- {
- buffer[--i] = Character.forDigit(num % radix, radix);
- num /= radix;
- }
- while (num > 0);
-
- if (isNeg)
- buffer[--i] = '-';
-
- return String.valueOf(buffer, i, 33-i);
- }
-
- /**
- * Creates a new Integer object using the String,
- * assuming a radix of 10.
- * @param s the String to convert.
- * @return the new Integer.
- * @see #Integer(java.lang.String)
- * @see #parseInt(java.lang.String)
- * @exception NumberFormatException thrown if the String
- * cannot be parsed as an int.
- */
- public static Integer valueOf(String s) throws NumberFormatException
- {
- return new Integer(parseInt(s));
- }
-
- /**
- * Creates a new Integer object using the String
- * and specified radix (base).
- * @param s the String to convert.
- * @param radix the radix (base) to convert with.
- * @return the new Integer.
- * @see #parseInt(java.lang.String,int)
- * @exception NumberFormatException thrown if the String
- * cannot be parsed as an int.
- */
- public static Integer valueOf(String s, int radix)
- throws NumberFormatException
- {
- return new Integer(parseInt(s, radix));
- }
-
- /**
- * Converts the specified String into an int.
- * This function assumes a radix of 10.
- *
- * @param s the String to convert
- * @return the int value of the String
- * argument.
- * @exception NumberFormatException thrown if the String
- * cannot be parsed as an int.
- */
- public static int parseInt(String s) throws NumberFormatException
- {
- return parseInt(s, 10);
- }
-
- /**
- * Converts the specified String into an int
- * using the specified radix (base).
- *
- * @param s the String to convert
- * @param radix the radix (base) to use in the conversion
- * @return the String argument converted to int.
- * @exception NumberFormatException thrown if the String
- * cannot be parsed as a int.
- */
- public static int parseInt(String str, int radix)
- throws NumberFormatException
- {
- final int len;
-
- if (str == null)
- throw new NumberFormatException ();
-
- if ((len = str.length()) == 0 ||
- radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
- throw new NumberFormatException();
-
- boolean isNeg = false;
- int index = 0;
- if (str.charAt(index) == '-')
- if (len > 1)
- {
- isNeg = true;
- index++;
- }
- else
- throw new NumberFormatException();
-
- return parseInt(str, index, len, isNeg, radix);
- }
-
- private static int parseInt(String str, int index, int len, boolean isNeg,
- int radix)
- throws NumberFormatException
- {
- int val = 0;
- int digval;
-
- int max = MAX_VALUE / radix;
- // We can't directly write `max = (MAX_VALUE + 1) / radix'.
- // So instead we fake it.
- if (isNeg && MAX_VALUE % radix == radix - 1)
- ++max;
-
- for ( ; index < len; index++)
- {
- if (val < 0 || val > max)
- throw new NumberFormatException();
-
- if ((digval = Character.digit(str.charAt(index), radix)) < 0)
- throw new NumberFormatException();
-
- // Throw an exception for overflow if result is negative.
- // However, we special-case the most negative value.
- val = val * radix + digval;
- if (val < 0 && (! isNeg || val != MIN_VALUE))
- throw new NumberFormatException();
- }
-
- return isNeg ? -(val) : val;
- }
-
- /**
- * Convert the specified String into an Integer.
- * The String may represent decimal, hexadecimal, or
- * octal numbers.
- *
- * The String argument is interpreted based on the leading
- * characters. Depending on what the String begins with (after an optional
- * minus sign), the base will be interpreted differently:
- *
- * | Leading Characters | Base |
|---|---|
| # | 16 |
| 0x | 16 |
| 0X | 16 |
| 0 | 8 |
| Anything Else | 10 |
String to interpret.
- * @return the value of the String as an Integer.
- * @exception NumberFormatException thrown if the String
- * cannot be parsed as an int.
- */
- public static Integer decode(String str) throws NumberFormatException
- {
- boolean isNeg = false;
- int index = 0;
- int radix = 10;
- final int len;
-
- if ((len = str.length()) == 0)
- throw new NumberFormatException("empty string");
-
- if (str.charAt(index) == '-')
- {
- // The minus sign should be followed by at least one more char
- if (len > 1)
- {
- isNeg = true;
- index++;
- }
- else
- throw new NumberFormatException();
- }
-
- if (str.charAt(index) == '#')
- {
- radix = 16;
- index++;
- }
- else if (str.charAt(index) == '0')
- {
- index++;
-
- // Check if str is just "0" or "-0"
- if (len == index)
- return new Integer(0);
-
- if (str.charAt(index) == 'x' || str.charAt(index) == 'X')
- {
- radix = 16;
- index++;
- }
- else
- radix = 8;
- }
-
- if (index >= len)
- throw new NumberFormatException("empty value");
-
- return new Integer(parseInt(str, index, len, isNeg, radix));
- }
-
- /** Return the value of this Integer as a byte.
- ** @return the value of this Integer as a byte.
- **/
- public byte byteValue()
- {
- return (byte) value;
- }
-
- /** Return the value of this Integer as a short.
- ** @return the value of this Integer as a short.
- **/
- public short shortValue()
- {
- return (short) value;
- }
-
- /** Return the value of this Integer as an int.
- ** @return the value of this Integer as an int.
- **/
- public int intValue()
- {
- return value;
- }
-
- /** Return the value of this Integer as a long.
- ** @return the value of this Integer as a long.
- **/
- public long longValue()
- {
- return value;
- }
-
- /** Return the value of this Integer as a float.
- ** @return the value of this Integer as a float.
- **/
- public float floatValue()
- {
- return value;
- }
-
- /** Return the value of this Integer as a double.
- ** @return the value of this Integer as a double.
- **/
- public double doubleValue()
- {
- return value;
- }
-
- /**
- * Compare two Integers numerically by comparing their
- * int values.
- * @return a positive value if this Integer is greater
- * in value than the argument Integer; a negative value
- * if this Integer is smaller in value than the argument
- * Integer; and 0, zero, if this
- * Integer is equal in value to the argument
- * Integer.
- *
- * @since 1.2
- */
- public int compareTo(Integer i)
- {
- if (this.value == i.value)
- return 0;
-
- // Returns just -1 or 1 on inequality; doing math might overflow.
- if (this.value > i.value)
- return 1;
-
- return -1;
- }
-
- /**
- * Behaves like compareTo(java.lang.Integer) unless the Object
- * is not a Integer. Then it throws a
- * ClassCastException.
- * @exception ClassCastException if the argument is not a
- * Integer.
- *
- * @since 1.2
- */
- public int compareTo(Object o)
- {
- return compareTo((Integer)o);
- }
-}