java long is 64 bits. The long data type is a 64-bit signed Java primitive data type. It is used when the calculation result of an integer may exceed the range of the int data type. Its value range is -9223372036854775808 to 9223372036854775807. All integers within the range of long are called integer literals of long type. Integer constants of long type always end with L or lowercase l, for example "long num1 = 0L;".
The operating environment of this tutorial: windows7 system, java8 version, DELL G3 computer.
Java long data type
The long data type is a 64-bit signed Java primitive data type.
Use when the calculation result of an integer may exceed the range of the int data type.
The range is -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
All integers within the range of long are called integer literals of type long. Integer constants of type long always end in L or lowercase l.
The following is an example of using an integer literal of type long:
long num1 = 0L; long num2 = 4L; long mum3 = -3; long num4 = 8; long num5 = -1L;
Long integer literal
The integer literal of type long can be used Represented in octal, hexadecimal and binary formats. For example,
long num1; num1 = 25L; // Decimal format num1 = 031L; // Octal format num1 = 0X19L; // Hexadecimal format num1 = 0b11001L; // Binary format
When a long literal is assigned to a variable of type long, the Java compiler checks the value to be assigned and ensures that it is within the scope of the long data type; otherwise a compile-time error is generated.
Note:Assignment from int to long is valid because all values that can be stored in an int variable can be stored in a long variable. However, the opposite is not true. You cannot simply assign the value stored in a long variable to an int variable. There is a possibility of value overflow.
To assign the value of a long variable to an int variable, use "cast" in Java as follows:
num1 = (int)num2;
Java has a class Long which defines two A constant to represent the maximum and minimum values of the long data types Long.MAX_VALUE and Long.MIN_VALUE.
long max = Long.MAX_VALUE; long min = Long.MIN_VALUE;
Extended knowledge: The following code can see how big the 64-bit value is
Long.MAX_VALUE // Prints 9,223,372,036,854,775,807 Long.MIN_VALUE // Prints -9,223,372,036,854,775,808
Perhaps, long can be used to calculate the distance traveled by light in a certain period of time. Light travels approximately 300,000 kilometers in one second. If you write a program to track the distance traveled by light, the int type will be out of range class after 7 seconds, while the long type will be able to calculate about 975 years. Don't believe it? You can take a look at the calculations in this gist (https://gist.github.com/jrg94/820d3f0f482dd19f0170964346381df0).
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