The compiler can easily and unequivocally prove that the first expression always results in an infinite loop, but it's not as easy for the second. In your toy example it's simple, but what if:

• the variable's contents were read from a file?
• the variable wasn't local and could be modified by another thread?
• the variable relied on some user input?

The compiler is clearly not checking for your simpler case because it's forgoing that road altogether. Why? Because it's much harder forbidden by the spec. See section 14.21:

• http://docs.oracle.com/javase/specs/jls/se7/html/jls-14.html#jls-14.21-300-M

(By the way, my compiler does complain when the variable is declared final.)

There is no difference in bytecode between while(true) and for(;;) but I prefer while(true) since it is less confusing (especially for someone new to Java).

You can check it with this code example

void test1(){
    for (;;){
        System.out.println("hello");
    }
}
void test2(){
    while(true){
        System.out.println("world");
    }
}

When you use command javap -c ClassWithThoseMethods you will get

  void test1();
    Code:
       0: getstatic     #15                 // Field java/lang/System.out:Ljava/io/PrintStream;
       3: ldc           #21                 // String hello
       5: invokevirtual #23                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
       8: goto          0

  void test2();
    Code:
       0: getstatic     #15                 // Field java/lang/System.out:Ljava/io/PrintStream;
       3: ldc           #31                 // String world
       5: invokevirtual #23                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
       8: goto          0

which shows same structure (except "hello" vs "world" strings) .