expression « Boolean « Java Data Type Q&A

1. Boolean expressions in Java

I have a question about the meaning (evaluation) of Boolean variables in return statements in Java. I know that:

if (var) { ... }
is the same as:
if (var==true) { ... }
In the second ...

2. Boolean expressions optimizations in Java

Consider the following method in Java:

public static boolean expensiveComputation() {
 for (int i = 0; i < Integer.MAX_VALUE; ++i);
 return false;
And the following main method:
public static void main(String[] args) {
 boolean ...

3. Boolean Expression Evaluation in Java

Hey everyone, Is there a relatively simpler (when compared with writing a parser) way to evaluate boolean expressions in Java? I do not want to use the JEP library. I have a String expression ...

4. Boolean expression order of evaluation in Java?

Suppose I have the following expression

String myString = getStringFromSomeExternalSource();
if (myString != null && myString.trim().length() != 0) {
Eclipse warns me that myString might be null in the second phrase of the boolean ...

5. What is the preferred way to write boolean expressions in Java

I have always written my boolean expressions like this:

if (!isValid) {
  // code
But my new employer insists on the following style:
if (false == isValid) {
  // code
Is one style ...

6. Can I strictly evaluate a boolean expression stored as a string in Java?

I would like to be able to evaluate an boolean expression stored as a string, like the following:

"hello" == "goodbye" && 100 < 101
I know that there are tons of questions ...

7. Would Java interpret this boolean expression in the way I wanted it to?

This is what I want: !A || (A && B && C) Is this equivalent to the original? !A || A && B && C why or why not? ...

8. Splitting up a boolean expression in Java

How can I split a boolean expression in Java? For example, I want to get the following from the expression a_1 & b_2 | (!c_3):

String tokens[] = {"a_1", "&", "b_2", "|", ...

9. evaluate boolean expression in java generate at runtime

How to evaluate complex boolean expressions generated at runtime in a Java program? Example: (x and y or z) and s with x, y, z boolean variables ... Thanks

10. Simplification of Boolean Expression in java

Is there any tool or library in java which simplifies a boolean expression formula and gives result. when inputs are like that,

exp = (a || a' ) result = 1

exp = ...

11. How to get boolean property with expression language?

If I have a class like this:

class Person {
  private int age;
  public int getAge() {
    return age;
  public boolean isAdult() {

12. The expressions which evaluate to a boolean value can not be concatenated with a String in Java. Why?

Let's see the following simplest code snippet in Java.

final public class Parsing
    public static void main(String[] args)

13. Resolving Boolean Expression

Given this input, i have to write a program to generate different possible combinations. ( ( ( A | B | C | D | F | G | E | H | I ) & J ) | ( ( A | D | H ) & L ) | ( ( B | G ) & M ) | ...

14. Help rqrd with math class and boolean expression

Thanx KYLE, This was a big help. NOw I understand that the random value was being casted as an integer before being multiplied by the constants, is that it? And the answer with the previous code was always zero that is why the compiler kept giving me "False" only. I have compiled and run the new code and it is giving ...

15. What is the difference between these boolean expression

The code in the first example fails to compile because the b=2 line is dependant on a conditional that could be false. In other words (a>3) might not always be true, in which case b would never get initialised. It's because you have a variable (a) in the conditional expression. The second example compiles ok because the conditional is always true ...

16. Evaluating boolean string expression

17. Use of identifiers in complex boolean expression

One way: int snarfblatt = fooValue * 10; int farnsworth = fooValue / 50; int fandango = fooValue - 80; if ( ( snarfblatt > 100 ) && ( ( farnsworth < 1 ) || ( fandango > 0 ) ) ) ... Of course, don't really use nonsense words: use words which add meaning. Instead of "snarfblatt", use a description ...

18. Help Evaluating Boolean Expressions

First, as somebody already mentioned, Demorgan's law is relevant here. Second, you need to know that we only care about X and !X here. So, for instance, give "a < 5" as X, we know that !X is "a >= 5". Anything else, such as "a <= 5", "a == 5", "a != 5", "a > 5", is irrelevant and will ...

19. Boolean expressions

Hi. I am attempting to make this return true if i is part of the list and return false if it does not. I cannot figure it out... Sorry this is such a newbie question... public boolean contains(String item) { for (String i : list) { if (i == item) { return true; } else { return false; } } } ...

20. Noob need HELP simple w/ Boolean expression equation!!!!

Can someone please help me out with this HW problem? THANK YOU!! 1.) Suppose that a variable L is true if an aircraft is in level flight, and false if the plane is in a landing or climbing phase. The landing gear should be lowered when both of the following conditions apply: -The aircraft is not in level flight and the ...

21. boolean expression examples

23. Taking out IF's and returning a boolean expression

someone told you that the code looked right? humm... don't look right to me. basically if the years are different you are done and know the answer but if the years are the same you must look to the month So why don't you have exactly the same situation to deal with the case where you only look at the day ...

24. Boolean Expression

26. Negating boolean expressions

I need a method that takes a simple boolean expression as the input and returns an arraylist containing possible negations of the input. The input can contain relational operators ( ==, !=, <, >, <=, and >=) and boolean operators (&& and ||). For "b+amt<0", it would return ["b+amt>=0"]. The most complex input I would need to evaluate and negate would ...

27. Need Help with Boolean expressions

This is just a quick one i did. my problem is that whenever i type 1 it goes straight away to catch statement. this is what happens: 1. Entre a digit 2. Exit 1 or 2: 1 Enter a digit: Wrong digit import java.util.*; public class stuff { public static void main(String[] args) { Scanner kb = new Scanner(; System.out.println("1. Entre ...

28. Help: boolean expressions

This might be a dumb question but Im new to Java and i have no idea what to do. I'm trying to make the line (! i || q) && (i || ! q) to work but keep on getting a error saying : G:\CSCI 120\CW\ operator ! cannot be applied to int System.out.println(i + " " + q + " ...

29. Dynamic execution of boolean expression

Hi folks, I want to execute a boolean expression dynamically, can you pls help me how to do it. For example, String str = " ( X & ( Y | Z ) ) " ; They value of X , Y or Z will be either true or false. After replacing their value, I will get string as follow String ...