What did I do wrong?

[GoingThroAPhase]

public class Question
{
public static void main ( String args[] )
{
int x = 5, y = 6;
float a = addParam ( x,y );
int b = addParam ( x,y );
System.out.printf ("a is %.2f and b is %d\n", a, b);
}

public static int addParam ( int a, int b )
{
return a + b;
}

public static float addParam ( int a, int b )
{
return a + b;
}
}

[Fubarable]

I don't know -- What is your question? That would go a long way towards helping others help you. Please have a look at the "Smart Questions" link as well as the Code Tags link in my signature below.

Much luck.

[gcalvin]

The return type is not part of the method signature, and you cannot have two methods with the same method signature.

-Gary-

[wangwei]

Great! You have learned a very very important part of java, method overloading. As Bruce Eckel said, method overloading is essential to allow the same method name to be used with different argument types. Now you can understand the meaning of overloading?
So, in your code:

float a = addParam ( x,y );
int b = addParam ( x,y );

for the x and y are both type int, and the complier doesn't know exactly what method to call, like gcalvin says, The return type is not part of the method signature.
But luckily, you can change your source to:

public class Question
{
    public static void main ( String args[] )
    {
        int x = 5, y = 6;
        float m = 5f, n = 6f;
        float a = addParam ( m, n ); // it will call the 2nd method without doubt
        int b = addParam ( x, y );
        System.out.printf ("a is %.2f and b is %d\n", a, b);
    }

    public static int addParam ( int a, int b )
    {
        return a + b;
    }

    public static float addParam ( float a, float b )
    {
        return a + b;
    }
}

Good luck!

[ŖàΫ ỏƒ Ңόρę]

First: you have two methods that have the same names

public static int addParam
public static float addParam

So, you have to change the name of one of them.