Java 7: how to copy 2d array by reference when array is inside object?

Java 7: how to copy 2d array by reference when array is inside object?

Object1.java:
public class Object1 {
public double[][] var1;
...
}
Object2.java:
public class Object2 {
public double[][] var2;
...
}
I want to copy by reference (shallow copy) Object2.var2 into Object1.var1.
Here's what I'm trying, which isn't working:
Object1 object1 = new Object1();
object1.var1=new double[2][];
System.arraycopy(object2.var2, 0, object1.var1, 0, object2.var2.length);
Anyone know where I'm going wrong? I'm getting
java.lang.NullPointerException compile error. Note that object2.var2 is
populated with data.