CODEWITHSUNDEEP
javaandroidconditional-statementslogical-operators
Björn Hallström
Björn Hallström

Reputation: 3833

logical operation in java

I have been trying to implement the following condition in a more sofisticated manner:

if (x > 1) 
 doSomething();
else {
 doSomethingElse();
}

want to code it like:

(x > 1) ? doSomething() : doSomethingElse();

Is this not possible at all?

Upvotes: 0

Views: 413

Answers (5)

johnchen902
johnchen902

Reputation: 9601

You can write things like this:

i = (x > 1) ? doSomething() : doSomethingElse();

But not directly like this:

(x > 1) ? doSomething() : doSomethingElse();

Because in JLS §14.8:

14.8. Expression Statements

Certain kinds of expressions may be used as statements by following them with semicolons. 

ExpressionStatement:
    StatementExpression ;

StatementExpression:
    Assignment
    PreIncrementExpression
    PreDecrementExpression
    PostIncrementExpression
    PostDecrementExpression
    MethodInvocation
    ClassInstanceCreationExpression

There is no ConditionalExpression in it.

Upvotes: 2

AllTooSir
AllTooSir

Reputation: 49372

Not possible if doSomething() returns void. Refer the JLS 15.25

The first expression must be of type boolean or Boolean, or a compile-time error occurs.

It is a compile-time error for either the second or the third operand expression to be an invocation of a void method.

In fact, by the grammar of expression statements (§14.8), it is not permitted for a conditional expression to appear in any context where an invocation of a void method could appear.

Eventually the second and third operand should evaluate to the same type, how this evaluation is done is also mentioned in the JLS.

P.S: Why you want to doSomething() for both true or false?

Upvotes: 4

Dennis Kriechel
Dennis Kriechel

Reputation: 3749

The ternary is used for inline if conditions. They need a return value, because u could write something like that:

System.out.println((x > 1) ? "True" : "False");

with void this would not be possible

Upvotes: 0

Manish Doshi
Manish Doshi

Reputation: 1193

It is dependent on return type.If you define like this void doSomething() then its not possible.

Upvotes: 0

Bathsheba
Bathsheba

Reputation: 234665

Not in full generality; the arguments in the ternary (formally the ternary requires expressions) have to evaluate to the same type.

If doSomething() is a void type then certainly not.

Upvotes: 1

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