Dead branch in if else statement

问题

I'm writing this code where you give the the program a name.

Java is telling me that the else in the statement is never used when it should be used if the variable "isACoolGuy" is false.

if (isACoolGuy = true){
        System.out.println("Thank you for this name... "+ name);
    }else if(isACoolGuy = false){    
        System.out.println("Okay im changing my name since you are an idiot");
        name = name = "jack";
        System.out.println("My name is "+ name + " now");

There is a switch statement earlier that should change the "isACoolGuy" Boolean to false.

case "name":
            System.out.println("You are an a******");
            isACoolGuy = false;
            break;

回答1:

your if is wrong

if (isACoolGuy == true){
        System.out.println("Thank you for this name... "+ name);
    }else if(isACoolGuy == false){
        System.out.println("Okay im changing my name since you are an idiot");
        name = "jack";
        System.out.println("My name is "+ name + " now");

or better

if (isACoolGuy){
        System.out.println("Thank you for this name... "+ name);
    }else if(!isACoolGuy){
        System.out.println("Okay im changing my name since you are an idiot");
        name =  "jack";
        System.out.println("My name is "+ name + " now");

and the most correct way in your case is to skip the else if and replace it with single else like this

if (isACoolGuy){
        System.out.println("Thank you for this name... "+ name);
    }else {
        System.out.println("Okay im changing my name since you are an idiot");
        name =  "jack";
        System.out.println("My name is "+ name + " now");

And some theory

isACoolGuy= true means assign true value to isACoolGuy variable . Using it inside an if always returns true isACoolGuy == true checks if the variable isACoolGuy has true value. It's comparation

Inside an if you can skip comparing boolean values since if has the following format

if(true)
{

}

so If(isACoolGuy) is similar to if(isACoolGuy==true)

回答2:

Instead of checking if it's true, you are assigning isACoolGuy to true and hence it always evaluates to true.

 if (isACoolGuy = true){

Instead use

 if (isACoolGuy == true){

Better use:-

if (isACoolGuy)

回答3:

To check the condition should use == not = it's for assignement, like this if(isACoolGuy == true).
Try to remove second condition if(isACoolGuy == false) is not necessasry, it's enough to have key word else like this:

  isACoolGuy = true;  
  ...
  if (isACoolGuy){ // the positive control
    System.out.println("Thank you for this name... "+ name);
 }else{    // otherwise negative
    ...
  }

来源：https://stackoverflow.com/questions/34406303/dead-branch-in-if-else-statement

标签

java

if-statement

switch-statement

case

naming