I have an array of Objects. Now my question is how I can find out what position the object is in from within it?
My object array
public myObject[] objects = new myObject[10];
The constructor of myObject
public myObject(){
int objectID = 0; //Here should be the code to find the position in the array
}
Loop over your array to find the position of your object, using whatever equality check you require.
EDIT:
As everyone seems to be concerned over .equals vs == I've changed the routine to perform either. If you're checking for reference equality, use findValue(ary, obj, true), otherwise use findValue(ary, obj, false)
This will not find null values. I suggest throwing an exception here if myObject is null, but I will leave that decision to you.
public int findValue(Object[] objects, Object myObject, boolean equalityCheck){
for(int i=0;i<objects.length;i++){
if(equalityCheck){
if(objects[i] == myObject){
return i;
}
}else{
if(objects[i]!=null && myObject!=null && objects[i].equals(myObject)){
return i;
}
}
}
return -1;
}
This code is performing a linear search to find the position of the object. Its not very efficient on larger arrays. As you seem to be a beginner I'm not going to dive into how to optimize this, but just be aware.
objects == myObject will never work in this case (but looks that upvoters don't even understand the problem with this approach).
== compares references, so in the first moment you use new ... you have a totally new reference. Now with your edit, it's not easy to see if you're indeed passing an existent element of the array to this method. When comparing object references, you should use equals instead of ==.
== with .equals in your code. == will always yields false in this case.Your class MyObject should have a method which gets the array and returns the idx
class MyObject {
public int findIdx(MyObject[] myObjects) {
if (myObjects != null) {
for (int i = 0; i <= myObjects.length; i++) {
if (myObjects[i].equals(this)) {
return i;
}
}
}
return -1;
}
}
