if(x)是否与if(x == true)相同? [英] Is if(x) same as if(x==true)?

问题描述

好吧，假设我有一个if语句和一个布尔值x:

Ok, so let's say I have an if statement and a boolean x:

if (x) {
    // some stuff
}

这是怎么回事?这和if(x == true)一样吗?

What happens here? Does this mean the same thing as if(x == true) ?

推荐答案

是

if(x) {

}

简明等同于

if(x == true) {

}

正如@Sotirios指出的那样，它们在字节码级别上是不同的.考虑以下Java类:

As @Sotirios points out, they are different at the bytecode level. Consider the following Java class:

class Test { 
   public void foo() { 
      boolean x = true;
      if(x == true) { 
      }
   }
}

发射:

  public void foo();
    Code:
       0: iconst_1      
       1: istore_1      
       2: iload_1       
       3: iconst_1      
       4: if_icmpne     7
       7: return 

vs

class Test { 
   public void foo() { 
      boolean x = true;
      if(x) { 
      }
   }
}

发出:

  public void foo();
    Code:
       0: iconst_1      
       1: istore_1      
       2: iload_1       
       3: ifeq          6
       6: return  

我认为这与程序的性能或正确性无关.

I don't think this has any bearing on the performance or correctness of the program.

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