how to use boolean data type in Java

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Java has a simple type, called boolean, for logical values. It can have only one of two possible values, true or false. This is the type returned by all relational operators, such as a < b. boolean is also the type required by the conditional expressions that govern the control statements such as if and for.

Here is a program that demonstrates the boolean type:

// Demonstrate boolean values.
class BoolTest {
public static void main(String args[]) {
boolean b;
b = false;
System.out.println("b is " + b);
b = true;
System.out.println("b is " + b);
// a boolean value can control the if statement
if(b) System.out.println("This is executed.");
b = false;
if(b) System.out.println("This is not executed.");
// outcome of a relational operator is a boolean value
System.out.println("10 > 9 is " + (10 > 9));
}
}

The output generated by this program is shown here:

b is false
b is true
This is executed.
10 > 9 is true

There are three interesting things to notice about this program. First, as you can see, when a boolean value is output by println( ), "true" or "false" is displayed. Second, the value of a boolean variable is sufficient, by itself, to control the if statement. There is no need to write an if statement like this:

if(b == true) ...

Third, the outcome of a relational operator, such as <, is a boolean value. This is why the expression 10 > 9 displays the value "true." Further, the extra set of parentheses around 10 > 9 is necessary because the + operator has a higher precedence than the >.


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Comments(7)


1. View Comment

thank you, this best for student like us,

View Tutorial          By: Srinath at 2012-05-12 15:04:03
2. View Comment

please would someone help me create a simple java billing program??? .... help me plxxxx!

View Tutorial          By: christopher at 2012-12-05 00:32:50
3. View Comment

A phone is considered a good phone if all of the following conditions are satisfied:-

The manufacturer must be one of Nokia, Samsung, Motorola, Sony or HTC.
The model name of the phone must be a single word. For example, "Razr", "Omnia" or "N8" will count, but "C6 01", "EVO 3D" or "Xperia Arc S" won't.
It must have either 'Android' or 'Windows' as its operating system.
If the CPU is of type "ARMv11" then the cpu speed must be atleast 1024 MHz.
If the CPU speed is less then 1024 MHz, then it must have a GPU and "Android" os only.
There should be atleast 30 carriers selling this phone and "Vodafone" must be one of them.

Write a method:

boolean isGoodPhone(String model, String manufacturer, String os, int CPUSpeed, String CPUType, boolean hasGPU, String[] carriers)

model Name of the phone model.
manufacturer Name of the phone manufacturer.
os Name of the operating system.
CPUSpeed CPU speed in MHz.
CPUType Type of the CPU.
hasGPU Whether or not the phone has Graphics Processing Unit (GPU).
carriers a string array representing list of carriers who sell this phone.


View Tutorial          By: harish at 2012-12-24 06:59:04
4. View Comment

how to return the boolean value. what is the data type to be mentioned?
public _______ getID();
{
return b;
}
what should be in ________


View Tutorial          By: karthick at 2013-02-07 10:21:28
5. View Comment

Nice stuff u guyzz are sharing

View Tutorial          By: kunal sharma at 2013-11-19 03:45:08
6. View Comment

thanks a lot

View Tutorial          By: Uzzal biswas at 2014-11-04 02:42:54
7. View Comment

thanksssssssssssss

View Tutorial          By: gajender sharma at 2015-02-02 09:15:05

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