20.7 The Class java.lang.Integer

public final class Integer extends Number {
	public static final int MIN_VALUE = 0x80000000;
	public static final int MAX_VALUE = 0x7fffffff;
	public Integer(int value);
	public Integer(String s)

		throws NumberFormatException;
	public String toString();
	public boolean equals(Object obj);
	public int hashCode();
	public int intValue();
	public long longValue();
	public float floatValue();
	public double doubleValue();
	public static String toString(int i);
	public static String toString(int i, int radix);
	public static String toHexString(long i);
	public static String toOctalString(long i);
	public static String toBinaryString(long i);
	public static int parseInt(String s)

		throws NumberFormatException;
	public static int parseInt(String s, int radix)

		throws NumberFormatException;
	public static Integer valueOf(String s)

		throws NumberFormatException;
	public static Integer valueOf(String s, int radix)

		throws NumberFormatException;
	public static Integer getInteger(String nm);
	public static Integer getInteger(String nm, int val);
	public static Integer getInteger(String nm, Integer val);
}

20.7.1 public static final int MIN_VALUE = 0x80000000;

The constant value of this field is -2147483648, the lowest value of type int.

20.7.2 public static final int MAX_VALUE = 0x7fffffff;

The constant value of this field is 2147483647, the highest value of type int.

20.7.3 public Integer(int value)

This constructor initializes a newly created Integer object so that it represents the primitive value that is the argument.

20.7.4 public Integer(String s) throws NumberFormatException

This constructor initializes a newly created Integer object so that it represents the integer represented by the string in decimal form. The string is converted to an int in exactly the manner used by the parseInt method (§20.7.18) for radix 10.

20.7.5 public String toString()

The integer value represented by this Integer object is converted to signed decimal representation and returned as a string, exactly as if the integer value were given as an argument to the toString method that takes one argument (§20.7.12).

Overrides the toString method of Object (§20.1.2).

20.7.6 public boolean equals(Object obj)

The result is true if and only if the argument is not null and is an Integer object that represents the same int value as this Integer object.

Overrides the equals method of Object (§20.1.3).

20.7.7 public int hashCode()

The result is the primitive int value represented by this Integer object.

Overrides the hashCode method of Object (§20.1.4).

20.7.8 public int intValue()

The int value represented by this Integer object is returned.

Overrides the intValue method of Number (§20.6.1).

20.7.9 public long longValue()

The int value represented by this Integer object is converted (§5.1.2) to type long and the result of the conversion is returned.

Overrides the longValue method of Number (§20.6.2).

20.7.10 public float floatValue()

The int value represented by this Integer object is converted (§5.1.2) to type float and the result of the conversion is returned.

Overrides the floatValue method of Number (§20.6.3).

20.7.11 public double doubleValue()

The int value represented by this Integer object is converted (§5.1.2) to type double and the result of the conversion is returned.

Overrides the doubleValue method of Number (§20.6.4).

20.7.12 public static String toString(int i)

The argument is converted to signed decimal representation and returned as a string, exactly as if the argument and the radix 10 were given as arguments to the toString method that takes two arguments (§20.7.13).

20.7.13 public static String toString(int i, int radix)

The first argument is converted to a signed representation in the radix specified by the second argument; this representation is returned as a string.

If the radix is smaller than Character.MIN_RADIX (§20.5.3) or larger than Character.MAX_RADIX (§20.5.4), then the value 10 is used instead.

If the first argument is negative, the first character of the result will be the character '-' ('\u002d'). If the first argument is not negative, no sign character appears in the result.

The remaining characters of the result represent the magnitude of the first argument. If the magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the magnitude will not be the zero character.The following ASCII characters are used as digits:

0123456789abcdefghijklmnopqrstuvwxyz

These are '\u0030' through '\u0039' and '\u0061' through '\u007a'. If the radix is N, then the first N of these characters are used as radix-N digits in the order shown. Thus, the digits for hexadecimal (radix 16) are 0123456789abcdef. If uppercase letters are desired, the toUpperCase method (§20.12.36) of class String may be called on the result:

Integer.toString(n, 16).toUpperCase()

20.7.14 public static String toHexString(int i)

The argument is converted to an unsigned representation in hexadecimal radix (base 16); this representation is returned as a string.

The result represents the unsigned magnitude of the argument. This equals the argument plus if the argument is negative; otherwise, it equals the argument.

If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the unsigned magnitude will not be the zero character. The following characters are used as hexadecimal digits:

0123456789abcdef

These are the characters '\u0030' through '\u0039' and '\u0061' through '\u0066'. If uppercase letters are desired, the toUpperCase method (§20.12.36) of class String may be called on the result:

Long.toHexString(n).toUpperCase()

20.7.15 public static String toOctalString(int i)

The argument is converted to an unsigned representation in octal radix (base 8); this representation is returned as a string.

The result represents the unsigned magnitude of the argument. This equals the argument plus if the argument is negative; otherwise, it equals the argument.

If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the unsigned magnitude will not be the zero character. The octal digits are:

01234567

These are the characters '\u0030' through '\u0037'.

20.7.16 public static String toBinaryString(int i)

The argument is converted to an unsigned representation in binary radix (base 2); this representation is returned as a string.

The result represents the unsigned magnitude of the argument. This equals the argument plus if the argument is negative; otherwise, it equals the argument.

If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the unsigned magnitude will not be the zero character. The characters '0' ('\u0030') and '1' ('\u0031') are used as binary digits.

20.7.17 public static int parseInt(String s)
throws NumberFormatException

The argument is interpreted as representing a signed decimal integer. The components of the string must all be decimal digits, except that the first character may be '-' ('\u002d') to indicate a negative value. The resulting integer value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseInt method that takes two arguments (§20.7.18).

20.7.18 public static int parseInt(String s, int radix)
throws NumberFormatException

The first argument is interpreted as representing a signed integer in the radix specified by the second argument. The components of the string must all be digits of the specified radix (as determined by whether Character.digit (§20.5.23) returns a nonnegative value), except that the first character may be '-' ('\u002d') to indicate a negative value. The resulting integer value is returned.

An exception of type NumberFormatException is thrown if any of the following situations occurs:

• The first argument is null or is a string of length zero.
• The radix is either smaller than Character.MIN_RADIX (§20.5.3) or larger than Character.MAX_RADIX (§20.5.4).
• Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\u002d') provided that the string is longer than length 1.
• The integer value represented by the string is not a value of type int.

Examples:

parseInt("0", 10) returns 0
parseInt("473", 10) returns 473
parseInt("-0", 10) returns 0
parseInt("-FF", 16) returns -255
parseInt("1100110", 2) returns 102
parseInt("2147483647", 10) returns 2147483647
parseInt("-2147483648", 10) returns -2147483648
parseInt("2147483648", 10) throws a NumberFormatException
parseInt("99", 8) throws a NumberFormatException
parseInt("Kona", 10) throws a NumberFormatException
parseInt("Kona", 27) returns 411787

20.7.19 public static Integer valueOf(String s)
throws NumberFormatException

The argument is interpreted as representing a signed decimal integer, exactly as if the argument were given to the parseInt method that takes one argument (§20.7.17). The result is an Integer object that represents the integer value specified by the string.

In other words, this method returns an Integer object equal to the value of:

new Integer(Integer.parseInt(s))

20.7.20 public static Integer valueOf(String s, int radix)
throws NumberFormatException

The first argument is interpreted as representing a signed integer in the radix specified by the second argument, exactly as if the arguments were given to the parseInt method that takes two arguments (§20.7.18). The result is an Integer object that represents the integer value specified by the string.

In other words, this method returns an Integer object equal to the value of:

new Integer(Integer.parseInt(s, radix))

20.7.21 public static Integer getInteger(String nm)

The first argument is treated as the name of a system property to be obtained as if by the method System.getProperty (§20.18.9). The string value of this property is then interpreted as an integer value and an Integer object representing this value is returned. If there is no property of the specified name, or if the property does not have the correct numeric format, then null is returned.

In other words, this method returns an Integer object equal to the value of:

getInteger(nm, null)

20.7.22 public static Integer getInteger(String nm, int val)

The first argument is treated as the name of a system property to be obtained as if by the method System.getProperty (§20.18.9). The string value of this property is then interpreted as an integer value and an Integer object representing this value is returned. If the property does not have the correct numeric format, then an Integer object that represents the value of the second argument is returned.

In other words, this method returns an Integer object equal to the value of:

getInteger(nm, new Integer(val))

but in practice it may be implemented in a manner such as:

Integer result = getInteger(nm, null);
return (result == null) ? new Integer(val) : result;

to avoid the unnecessary allocation of an Integer object when the default value is not needed.

20.7.23 public static Integer getInteger(String nm, Integer val)

The first argument is treated as the name of a system property to be obtained as if by the method System.getProperty (§20.18.9). The string value of this property is then interpreted as an integer value and an Integer object representing this value is returned.

• If the property value begins with the two ASCII characters 0x or the ASCII character #, not followed by a minus sign, then the rest of it is parsed as a hexadecimal integer exactly as for the method Integer.valueOf (§20.7.20) with radix 16.
• If the property value begins with the ASCII character 0 followed by another character, it is parsed as an octal integer exactly as for the method Integer.valueOf (§20.7.20) with radix 8.
• Otherwise, the property value is parsed as a decimal integer exactly as for the method Integer.valueOf (§20.7.20) with radix 10.

The second argument serves as a default value. If there is no property of the specified name, or if the property does not have the correct numeric format, then the second argument is returned.