Declaration is intimation to the compiler about the nature of Data a reference is going to hold.
For example - List myList;
Instantiation is reservation of memory.
For example
myList = new ArrayList();
Initialization or construction is setting the default values for member elements.
For example
myList = new ArrayList(mySet);
** Example 2nd is both for instantiation as well as initialization. The only difference is that 2nd will initialized the member elements to their default values whereas 3rd will initialized it with the elements from set.
For example - List myList;
Instantiation is reservation of memory.
For example
myList = new ArrayList();
Initialization or construction is setting the default values for member elements.
For example
myList = new ArrayList(mySet);
** Example 2nd is both for instantiation as well as initialization. The only difference is that 2nd will initialized the member elements to their default values whereas 3rd will initialized it with the elements from set.