Question

Background

I am working with functions which which passes arguments as pointers. I need to convert a function which is written in C to JAVA with the same behavior as in C. I am developing for Android in Eclipse under Windows.

C Function Example

int testFunction( char* firstName, char* SecomdName, char* lastname, int age);

This function takes 3 pointers to char values and initializes them, so in C I can write something like the following to initialize all three pointers:

char* v1, v2, v3;
int res = testFunction(v1, v2, v3, 54);

After the call to testFunction, the variables v1, v2, v3 will be initialized with some values.

JAVA Function Example

int testFunction( String firstName, String secondName, String lastName, int age);

This is the same function as in C but written in JAVA, however in JAVA there are no pointers which means that I can’t write something like this:

String v1, v2, v3;
testFunction(v1, v2, v3, 54);

Question:

What can I do to get the same initialization behavor for my JAVA function as in the C example? Is this possible?

Answer 1

There’s a few things you could do. You could create a bean class that contains the fields you want to create, ie something like:

 public class Names {
     String firstName;
     String secondName;
     String lastName;
     int returnValue;

     // getters/constructors etc ommitted...
 }

Your testFunction could then instantiate a Names object and return it, ie.

 Names names = testFunction(int age);
 String firstName = names.getFirstName();
 // etc... 

An alternative, if you’re dealing with Strings is to pass through StringBuilder objects, ie

int testFunction(StringBuilder firstName, StringBuilder secondName, StringBuilder lastName, int age) {
   // Use StringBuilder methods such as append to create the strings eg...
   firstName.append("Bob");
}

Then elsewhere in your code you could use…

StringBuilder firstNameBuilder = new StringBuilder();
StringBuilder secondNameBuilder = new StringBuilder();
StringBuilder thirdNameBuilder = new StringBuilder();

testFunction(firstNameBuilder, secondNameBuilder, thirdNameBuilder, 84);

String firstName = firstNameBuilder.toString();  // firstName now equals "Bob"
/// etc...