Question

import javax.swing.JOptionPane;

public class Mate {

double suma (double x1,double x2)
    {return x1+x2;}

double suma (double x1,double x2,double x3)
    {return x1+x2+x3;}

double suma (int num [ ])

    {int i=num.length;
     int j=0;
     int s=0;

for(j=0;j < i;j++)

{return (double)(s);}}} // here appears the error "missing return statement"

class AplicacionMate

{public static void main (String arg [])

    {int n[ ]={5,4,3,2,1};
     double r=0.0;
     Mate m=new Mate ( );
     r=m.suma(5,4);
     JOptionPane.showMessageDialog(null,"La suma 1="+r);
     r=m.suma(5,5,4);
     JOptionPane.showMessageDialog(null,"La suma 2="+r);
     r=m.suma(n);
     JOptionPane.showMessageDialog(null,"La suma del arreglo="+r);
     System.exit(0);}}

Answer 1

I took the liberty of formatting your code. This is how the method looks:

double suma (int num [ ]) {
    int i=num.length;
    int j=0;
    int s=0;

    for(j=0;j < i;j++) {
        return (double)(s);
    }
}

I suspect you attempted to write a sum-method, started with a stub, and didn’t get it to compile. This is probably what you had in mind:

double suma (int num [ ]) {
    int i=num.length;
    int j=0;
    int s=0;

    for(j=0;j < i;j++) {
        // here you probably want s += num[j];
    }

    return (double)(s);

}

---

The Java compiler can only deduce that a statement (such as a return) is reachable in very simple cases. (To illustrate: this method does compile. Still not very useful though!)

double suma (int num [ ]) {
    int i=num.length;
    int j=0;
    int s=0;

    for(j=0; true; j++) {
        return (double)(s);
    }
}