java - The difference between = and == -

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what difference between = true , == true in :

 void startengine(){    if ( enginestat == true )        system.out.println("the engine on ");  else { enginestat = true;        system.out.println("the engine on");        }

== outputs boolean represents whether 2 expressions equal. (the boolean equal true or false).

= assigns value of expression on right side variable on left.


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