Java Reference
In-Depth Information
We change our program segment to prompt the user for keyboard input and,
as an example, print the square of the integer that was typed:
//
Prompt the user for an integer, store it in
s
, and print its square
System.out.println("Please type an integer");
s= JLiveRead.readLineInt();
System.out.println(" square is " + (s*s));
Reading values of other primitive types
Class
JLiveRead
contains methods for reading a line of input that contains
values of other primitive types. In each case, the item read may be preceded and
followed by blank characters. There is also a method for reading the whole line
as a
String
. The methods are:
•
readLineLong()
: Read and return a
long
value.
•
readLineFloat()
: Read and return a
float
value.
•
readLineDouble()
: Read and return a
double
value.
•
readLineNonwhiteChar()
: Read and return the first
char
value that is not
whitespace.
•
readLineBoolean()
: The input may contain “
t
”, “
true
”, “
f
”, or “
false
”,
using lowercase or uppercase. Read it and return
true
or
false
, accordingly.
•
readLineString()
: Read and return a sequence of non-whitespace characters,
as a
String
.
One more useful method can be used to read in all the typed characters:
•
readString()
: Read and return the typed characters, as a
String
. The final
carriage return or line feed is not included.
Putting more than one value on a line
The methods discussed above force the user to type exactly one value before
hitting the return/enter key. For example, function
readLineInt
will complain
and ask you to type an integer again if you type the following before hitting the
return/enter key:
25 4.0 3
Class JLiveRead contains methods that read a single value from a line, per-
haps preceded by whitespace, leaving the rest of the line to be read later. These
methods are:
readInt()
readLong()
readFloat()
readDouble()
readWord()
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