The return statement does not have to pass a value back at all. It can just be used to return control to the calling program. Once a return statement has been executed, the code which follows it is not executed. You can see what I mean in the example below:
andrew@UBUNTU:~/Java$ cat Number_Check.java
public class Number_Check
{
public void check_number(int a)
{
if (a < 10)
{
System.out.println(a + " < 10");
return;
}
// The next line is ignored if the number supplied
// is less than 10:
System.out.println(a + " >= 10");
}
}
andrew@UBUNTU:~/Java$ javac Number_Check.java
andrew@UBUNTU:~/Java$
andrew@UBUNTU:~/Java$ cat Number_Check_Test.java
class Number_Check_Test
{
public static void main(String args[])
{
Number_Check x = new Number_Check();
x.check_number(9);
x.check_number(10);
x.check_number(11);
}
}
andrew@UBUNTU:~/Java$ javac Number_Check_Test.java
andrew@UBUNTU:~/Java$ java Number_Check_Test
9 < 10
10 >= 10
11 >= 10
andrew@UBUNTU:~/Java$
However, if the compiler sees code which will NEVER execute, it returns a compilation error:
andrew@UBUNTU:~/Java$ cat Another_Number_Check.java
public class Another_Number_Check
{
public void check_number(int a)
{
if (a < 10)
{
System.out.println(a + " < 10");
return;
}
else
{
System.out.println(a + " >= 10");
return;
}
System.out.println("This line is ignored");
}
}
andrew@UBUNTU:~/Java$ javac Another_Number_Check.java
Another_Number_Check.java:15: unreachable statement
System.out.println("This line is ignored");
^
1 error
andrew@UBUNTU:~/Java$
