Which one is fast?

Question

public class Point2D {
    private int x, y;
    public Point2D() { x = 0; y = 0; }
    //public Point2D() { this(0,0); }
    public Point2D(int x, int y) {this.x = x; this.y = y;}
    public int getX() {return x;}
    public int getY() {return y;}
    public void setX(int x) {this.x = x;}
    public void setY(int y) {this.y = y;}
}the constructors below both work:
public Point2D() { x = 0; y = 0; }
//public Point2D() { this(0,0); }
which one should be more efficient?
thanks

Answer 1

A good compiler would generate the same code for both
forms of no argument constructor.
public class b {
int x,y;
public b(int x,int y) { this.x=x; this.y=y;}
public b(int x) { this(x,0); }
public b() { x=0; y=0;} //
public static void main(String args[] ) {
     b w0,w1;
}With SUN JDK 1.4.2_03:
javap -private -c b
Compiled from "b.java"
public class b extends java.lang.Object{
int x;
int y;
public b(int,int);
  Code:
   0:     aload_0
   1:     invokespecial     #1; //Method java/lang/Object."<init>":()V
   4:     aload_0
   5:     iload_1
   6:     putfield     #2; //Field x:I
   9:     aload_0
   10:     iload_2
   11:     putfield     #3; //Field y:I
   14:     return
public b(int);
  Code:
   0:     aload_0
   1:     iload_1
   2:     iconst_0
   3:     invokespecial     #4; //Method "<init>":(II)V
   6:     return
public b();
  Code:
   0:     aload_0
   1:     invokespecial     #1; //Method java/lang/Object."<init>":()V
   4:     aload_0
   5:     iconst_0
   6:     putfield     #2; //Field x:I
   9:     aload_0
   10:     iconst_0
   11:     putfield     #3; //Field y:I
   14:     return
public static void main(java.lang.String[]);
  Code:
   0:     return
}