Cleanest way to toggle a boolean variable in Java?

问题:

Is there a better way to negate a boolean in Java than a simple if-else?

if (theBoolean) {     theBoolean = false; } else {     theBoolean = true; } 

回答1:

theBoolean = !theBoolean; 

回答2:

theBoolean ^= true; 

Fewer keystrokes if your variable is longer than four letters

回答3:

There are several

The "obvious" way (for most people)

theBoolean = !theBoolean; 

The "shortest" way (most of the time)

theBoolean ^= true; 

The "most visual" way (most uncertainly)

theBoolean = theBoolean ? false : true; 

Extra: Toggle and use in a method call

theMethod( theBoolean ^= true ); 

Since the assignment operator always returns what has been assigned, this will toggle the value via the bitwise operator, and then return the newly assigned value to be used in the method call.

回答4:

If you use Boolean NULL values and consider them false, try this:

static public boolean toggle(Boolean aBoolean) {     if (aBoolean == null) return true;     else return !aBoolean; } 

If you are not handing Boolean NULL values, try this:

static public boolean toggle(boolean aBoolean) {    return !aBoolean; } 

These are the cleanest because they show the intent in the method signature, are easier to read compared to the ! operator, and can be easily debugged.

Usage

boolean bTrue = true boolean bFalse = false boolean bNull = null  toggle(bTrue) // == false toggle(bFalse) // == true toggle(bNull) // == true 

Of course, if you use Groovy or a language that allows extension methods, you can register an extension and simply do:

Boolean b = false b = b.toggle() // == true 

回答5:

Before:

boolean result = isresult(); if (result) {     result = false; } else {     result = true; } 

After:

boolean result = isresult(); result ^= true; 

文章来源: Cleanest way to toggle a boolean variable in Java?