Error of "Class has no return statement"

i can't figure out way the compiler say's the class has no return statement .....

Code :

---

import java.io.*;
 
class ConsoleInput { // open class
 
    public static String readLine() { // open readLine
        try { // open try
            StringBuffer line = new StringBuffer();
            int a = 0;
            char b;
            System.out.println("input here:");
            BufferedInputStream buff = new BufferedInputStream(System.in);
 
            while (a != -1) { // open while
                a = buff.read();
                b = (char) a;
                line.append(b);
            } // close while
            String sLine = line.toString();
            if (sLine.length() == 0) { // open if
                sLine = "no string";
            } // close if
            buff.close();
            return sLine;
        } catch (IOException e) { // open catch close try
            System.out.println(e.getMessage());
        } // close catch
    } // close readLine
 
} // close class

---

Hello mdstrauss,

The return statement is used to explicitly return from a method. That is, it causes program control to transfer back to the caller of the method.
Whenever your method is a variable type like String, the method must always return a String result.

This is untested but for example:

Code :

---

import java.io.*;
 
class ConsoleInput { // open class
 
    public static String readLine() { // open readLine
 
        try { // open try
            StringBuffer line = new StringBuffer();
            int a = 0;
            char b;
            System.out.println("input here:");
            BufferedInputStream buff = new BufferedInputStream(System.in);
 
            while (a != -1) { // open while
                a = buff.read();
                b = (char) a;
                line.append(b);
            } // close while
            String sLine = line.toString();
            if (sLine.length() == 0) { // open if
                sLine = "no string";
            } // close if
            buff.close();
            return sLine;
        } catch (IOException e) { // open catch close try
            System.out.println(e.getMessage());
        } // close catch
        [B]return readLine();[/B]
    } // close readLine
 
} // close class

---

Or you can always make the return method void:

Code :

---

import java.io.*;
 
class ConsoleInput { // open class
 
    public static [B]void [/B]readLine() { // open readLine
 
        try { // open try
            StringBuffer line = new StringBuffer();
            int a = 0;
            char b;
            System.out.println("input here:");
            BufferedInputStream buff = new BufferedInputStream(System.in);
 
            while (a != -1) { // open while
                a = buff.read();
                b = (char) a;
                line.append(b);
            } // close while
            String sLine = line.toString();
            if (sLine.length() == 0) { // open if
                sLine = "no string";
            } // close if
            buff.close();
            //return sLine;
        } catch (IOException e) { // open catch close try
            System.out.println(e.getMessage());
        } // close catch
 
    } // close readLine
 
} // close class

---

thank you it works but i don't understand in method readLine i have all ready a return statement that returns string

return sLine;

way do i need the second return statement

return readLine();

in the readLine method ???

In the case where the first return statement won't be reached like for instance in an if you still need to have a return.

Hope that makes sense.

// Json

i don't get it way do i need two of the returns one before the catch and one after
way not put only one after the catch and way the second one is "return readLine()"
and not "return sLine" ?


i don't get way the catch block makes a deference ??


and i don't see where in my program there could be a hole with no return the if is to insure the is a return
no matter what....?????



thank you very much for the help
i am knew to java .....

ok i understood that if my program catch's a exception then there would be no return but way dose the program no recognize my sLine string it is still in the method ?????


i checked all these and they compile

Code :

---

 
import java.io.*;
 
 
class ConsoleInput
{
 
 
 
public static String readLine()
  { 
  try{
StringBuffer line = new StringBuffer();
int a = 0 ;
char b;
System.out.println("input here:");
BufferedInputStream buff = new BufferedInputStream(System.in);
 
 
    while (a != -1 )
        {
          a = buff.read();
          b = (char) a;
          line.append(b);
        }
string sLine = line.toString();
 
buff.close();
return sLine;
  }catch (IOException e){
                  System.out.println(e.getMessage());
                    [B]return null;[/B]
                             } 
 
      }   
 
 
 
 
}

---

or this

Code :

---

 
import java.io.*;
 
 
class ConsoleInput
{
[B]static String sLine;[/B]
 
 
public static String readLine()
  { 
  try{
StringBuffer line = new StringBuffer();
int a = 0 ;
char b;
System.out.println("input here:");
BufferedInputStream buff = new BufferedInputStream(System.in);
 
 
    while (a != -1 )
        {
          a = buff.read();
          b = (char) a;
          line.append(b);
        }
sLine = line.toString();
if (sLine.length()==0){ 
sLine = "no string";
}   
buff.close();
return sLine;
  }catch (IOException e){
                  System.out.println(e.getMessage());
 
                             } 
            [B]return sLine;[/B]
      }   
 
 
 
 
}

---

Well basically when you have a return type on a method you must make sure the method returns something unless it throws an exception so even if you have a try catch in there you have to make sure you return something if you catch an exception. You could of course put your return after the catch which will be alright.

There is a minor flaw in your code though, I see you are using a BufferedInputStream and you call close() in the try, but if an exception is thrown while you do buff.read() you will never reach the buff.close() and hence you will get a memory leak in your program every time you hit this method.

Try something like this (with reservation for any errors as I type this from the top of my head):

Code :

---

    BufferedInputStream buff = null;
 
    try {
        buff = new BufferedInputStream(System.in);
        // Do some stuff with the buffer here
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        // Close the buffer here, because this will always
        if(buff != null) {
            try {
                buff.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

---

// Json

thank you very very much your write it dose not work it keeps open a strem even if my input is enter say what is a memory leak and well it happen no matter if i get a exception i'll check your advice latter because i have to go

again thank you very much