Return values and methods repost

Had to repost for clarity. I'm working on a program which not only could I not compile...and have already been adviced on the forum it's well of the mark. Kindly request a few pointers ( !code ) on where i'm going wrong. I'll put the question as put to me and the code I originally thought was close to archieving th task.
Here goes,
The following code fragment is the main method for a simple program. The program reads in the ages of 3 people. Each age is checked for validity. If all ages are valid the program will then calculate the age of the oldest person and the average age(which is to be represented as a double).
The method names highlighted in bold require implementation(note some method calls are duplicated, but this doesn't mean you have to write the method more than once!). The first takes an integer parameter and returns true or false depending on whetherthe age is valid, i.e. between some sensible limits. The remaining methods both take threeparameters, all intergers. oldest displays the highest age value; average returns the average of the ages.
public class Tut11_1{
public static void main(String[] args){
    GUI gui=new GUI();
    int age1=0;
    int age2=0;
    int age3=0;
    double average=0;
    age1=gui.getInt("Enter first age");
    age2=gui.getInt("Enter second age");
    age3=gui.getInt("Enter third age");
    if(!isValidAge(age1))
         gui.putText("Age 1 is not valid");
    else if(!isValidAge(age1))
         gui.putText("Age 2 is not valid");
    else if(!isValidAge(age1))
         gui.putText("Age 3 is not valid");
    else
         oldest(age1, age2, age3);
         average=averageAge(age1, age2, age3);
         gui.putText("Average age is " + average);
    This is where i've got to....
public class Tut11_1{
public static void main(String[] args){
    GUI gui=new GUI();
    int age1=0;
    int age2=0;
    int age3=0;
    double average=0;
    age1=gui.getInt("Enter first age");
    age2=gui.getInt("Enter second age");
    age3=gui.getInt("Enter third age");
    if(!isValidAge(age1))
         gui.putText("Age 1 is not valid");
    else if(!isValidAge(age1))
         gui.putText("Age 2 is not valid");
    else if(!isValidAge(age1))
         gui.putText("Age 3 is not valid");
    else
         oldest(age1, age2, age3);
         average=averageAge(age1, age2, age3);
         gui.putText("Average age is " + average);
    //implementing method names
    public static Boolean isValidAge(int oldest, double averageAge, double average)
         if(isValidAge<=0)
              return false;
         else if(isValidAge<=100)
              return true;
         else if(isValidAge>100)
              return false;
         else
              oldest(age1, age2, age3);
            return oldest;
            average=averageAge(age1, age2, age3);
            return average;
    }

N_E_W_B_I_E wrote:
That seem to make sense...will give that a go. On the case of boolean would this be right?
public static boolean isValidAge(_DONT I HAVE TO DECLARE ANYTHING HERE_ )To be honest with you I am not seeing alot of hope of you completing this assignment without one on one help.
This is just to give you a push in the right direction. I wouldn't normally do this but it's not all of your assignment and there seems to be a real lack of progress in your two threads thus far....
public static boolean isValidAge(int age){
if(age<=0){
return false;
return age<100;
}So that method is now finished. When you call it you can do this...
int x = 17;//or whatever the user inputs
boolean validAge = isValidAge(x);
if(validAge==true){
}else{
}The above can be compressed (because an if is a true/false and boolean is a true false) as
int x = 17;//or whatever the user inputs
if(isValidAge(x)){
}else{
}

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