Java public int length

Class Integer

The Integer class wraps a value of the primitive type int in an object. An object of type Integer contains a single field whose type is int .

In addition, this class provides several methods for converting an int to a String and a String to an int , as well as other constants and methods useful when dealing with an int .

This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.

Implementation note: The implementations of the «bit twiddling» methods (such as highestOneBit and numberOfTrailingZeros ) are based on material from Henry S. Warren, Jr.’s Hacker’s Delight, (Addison Wesley, 2002).

Field Summary

Constructor Summary

Method Summary

Returns the number of one-bits in the two’s complement binary representation of the specified int value.

Returns the value obtained by compressing the bits of the specified int value, i , in accordance with the specified bit mask.

Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.

Returns the unsigned quotient of dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.

Returns the value obtained by expanding the bits of the specified int value, i , in accordance with the specified bit mask.

Returns an int value with at most a single one-bit, in the position of the highest-order («leftmost») one-bit in the specified int value.

Returns an int value with at most a single one-bit, in the position of the lowest-order («rightmost») one-bit in the specified int value.

Returns the number of zero bits preceding the highest-order («leftmost») one-bit in the two’s complement binary representation of the specified int value.

Returns the number of zero bits following the lowest-order («rightmost») one-bit in the two’s complement binary representation of the specified int value.

Parses the CharSequence argument as a signed int in the specified radix , beginning at the specified beginIndex and extending to endIndex — 1 .

Parses the CharSequence argument as an unsigned int in the specified radix , beginning at the specified beginIndex and extending to endIndex — 1 .

Returns the unsigned remainder from dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.

Returns the value obtained by reversing the order of the bits in the two’s complement binary representation of the specified int value.

Returns the value obtained by reversing the order of the bytes in the two’s complement representation of the specified int value.

Returns the value obtained by rotating the two’s complement binary representation of the specified int value left by the specified number of bits.

Returns the value obtained by rotating the two’s complement binary representation of the specified int value right by the specified number of bits.

Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument.

Returns an Integer object holding the value extracted from the specified String when parsed with the radix given by the second argument.

Methods declared in class java.lang.Object

Field Details

MIN_VALUE

MAX_VALUE

TYPE

SIZE

BYTES

Constructor Details

Integer

It is rarely appropriate to use this constructor. The static factory valueOf(int) is generally a better choice, as it is likely to yield significantly better space and time performance.

Integer

It is rarely appropriate to use this constructor. Use parseInt(String) to convert a string to a int primitive, or use valueOf(String) to convert a string to an Integer object.

Constructs a newly allocated Integer object that represents the int value indicated by the String parameter. The string is converted to an int value in exactly the manner used by the parseInt method for radix 10.

Method Details

toString

Returns a string representation of the first argument in the radix specified by the second argument. If the radix is smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX , then the radix 10 is used instead. If the first argument is negative, the first element of the result is the ASCII minus 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:

These are ‘\u0030’ through ‘\u0039’ and ‘\u0061’ through ‘\u007A’ . If 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 String.toUpperCase() method may be called on the result:

toUnsignedString

Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument. If the radix is smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX , then the radix 10 is used instead. Note that since the first argument is treated as an unsigned value, no leading sign character is printed. 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 behavior of radixes and the characters used as digits are the same as toString .

toHexString

Returns a string representation of the integer argument as an unsigned integer in base 16. The unsigned integer value is the argument plus 2 32 if the argument is negative; otherwise, it is equal to the argument. This value is converted to a string of ASCII digits in hexadecimal (base 16) with no extra leading 0 s. The value of the argument can be recovered from the returned string s by calling Integer.parseUnsignedInt(s, 16) . 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:

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

toOctalString

Returns a string representation of the integer argument as an unsigned integer in base 8. The unsigned integer value is the argument plus 2 32 if the argument is negative; otherwise, it is equal to the argument. This value is converted to a string of ASCII digits in octal (base 8) with no extra leading 0 s. The value of the argument can be recovered from the returned string s by calling Integer.parseUnsignedInt(s, 8) . 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 octal digits:

toBinaryString

Returns a string representation of the integer argument as an unsigned integer in base 2. The unsigned integer value is the argument plus 2 32 if the argument is negative; otherwise it is equal to the argument. This value is converted to a string of ASCII digits in binary (base 2) with no extra leading 0 s. The value of the argument can be recovered from the returned string s by calling Integer.parseUnsignedInt(s, 2) . 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.

toString

Returns a String object representing the specified integer. The argument is converted to signed decimal representation and returned as a string, exactly as if the argument and radix 10 were given as arguments to the toString(int, int) method.

toUnsignedString

Returns a string representation of the argument as an unsigned decimal value. The argument is converted to unsigned decimal representation and returned as a string exactly as if the argument and radix 10 were given as arguments to the toUnsignedString(int, int) method.

parseInt

• The first argument is null or is a string of length zero.
• The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX .
• Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign ‘-‘ ( ‘\u002D’ ) or plus sign ‘+’ ( ‘\u002B’ ) provided that the string is longer than length 1.
• The value represented by the string is not a value of type int .

parseInt("0", 10) returns 0 parseInt("473", 10) returns 473 parseInt("+42", 10) returns 42 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

parseInt

public static int parseInt (CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException

Parses the CharSequence argument as a signed int in the specified radix , beginning at the specified beginIndex and extending to endIndex — 1 . The method does not take steps to guard against the CharSequence being mutated while parsing.

parseInt

Parses the string argument as a signed decimal integer. The characters in the string must all be decimal digits, except that the first character may be an ASCII minus sign ‘-‘ ( ‘\u002D’ ) to indicate a negative value or an ASCII plus sign ‘+’ ( ‘\u002B’ ) to indicate a positive value. The resulting integer value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseInt(java.lang.String, int) method.

parseUnsignedInt

• The first argument is null or is a string of length zero.
• The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX .
• Any character of the string is not a digit of the specified radix, except that the first character may be a plus sign ‘+’ ( ‘\u002B’ ) provided that the string is longer than length 1.
• The value represented by the string is larger than the largest unsigned int , 2 32 -1.

parseUnsignedInt

public static int parseUnsignedInt (CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException

Parses the CharSequence argument as an unsigned int in the specified radix , beginning at the specified beginIndex and extending to endIndex — 1 . The method does not take steps to guard against the CharSequence being mutated while parsing.

parseUnsignedInt

Parses the string argument as an unsigned decimal integer. The characters in the string must all be decimal digits, except that the first character may be an ASCII plus sign ‘+’ ( ‘\u002B’ ). The resulting integer value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseUnsignedInt(java.lang.String, int) method.

valueOf

Returns an Integer object holding the value extracted from the specified String when parsed with the radix given by the second argument. 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(java.lang.String, int) method. 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:

valueOf

Returns an Integer object holding the value of the specified String . The argument is interpreted as representing a signed decimal integer, exactly as if the argument were given to the parseInt(java.lang.String) method. 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:

valueOf

Returns an Integer instance representing the specified int value. If a new Integer instance is not required, this method should generally be used in preference to the constructor Integer(int) , as this method is likely to yield significantly better space and time performance by caching frequently requested values. This method will always cache values in the range -128 to 127, inclusive, and may cache other values outside of this range.

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