Why do we intialize other classes in constructor ????

Question

Please see the question below:
class MThread extends Thread {
private Abc mfact = null;
private Xyz mo = null;
private Pro sts = null;
* Constructor.
public MThread(Abc mfact, Xyz mo ) { *// do i have to pass Pro here from calling method so that i can initialize in constructor in order to use its method like record ???*
this.mfact = mfact;
this.mo = mo;
public somemethod() {
sts.record();
public void somemethod1() {
mo.create();
***************************************************Another Class******************************************************
public class Xyz{
// Some code here
// this class calls Mthread and creates 10 such Threads sth like
for (int i = 0; i < 10; i++) {
mThreads[i] = new MThread(mfact, mo;
***********Another Class ****************
public class Pro {
// some code
public synchronized record() {
rat ++;
Explanation :
Xyz calls Mthread 10 times to create such threads.
Mthread has method that class Pro for stats recording
Mthread also uses other class files to do some functioning of its own.
Question:
Please see the question in the constructor of Mthread ??
for using method like record in Pro. do i have to initialize that in the constructor of Mthread ??
because other class like Abc initializes itself in the construtor??
Why do we have to initialize some class in constructor ?? I don't get it ?? Also when i press F3 (Open declaration ) on record call in somemethod ()
.. it properly opens the file of class Pro and points to my sychronized method in that class ??
CONFUSED... Please help ..
Thank you

Answer 1

javanewbie83 wrote:
To morgair:
thats right..so actually my question was do i need to change the requiremensts of the constructor so i can pass in the value of class Pro from the calling method.
Do i need to do that. is that compulsory to use one of its methods
ThanksYes, somehow you have to get visibility to your object that you want to use. If it's not passed in, then you have to have it in some global context with reference to where you want to use it.
class myClass{
  A a;
  B b;
  C c;
  myClass(A a, B b, C c){
    this.a = a;
    this.b = b;
    this.c = c;
  public void myMethod(){
    c.doSomething(a, b);
// This can be done since a and b are supplied as arguments to the constructor
// but also consider this:
class myClass{
  A a;
  B b;
  C c;
  myClass(A a, B b){
    this.a = a;
    this.b = b;
    c = new C();
  public void myMethod(){
    c.doSomething(a, b);
//this will also work but c is a local variable
//also consider this:
class myOuterClass{
  A a;
  B b;
  C c;
  myOuterClass(){
    a = new A();
    b = new B();
    c = new C();
    //do stuff
  public void someStuff(){ 
    myInnerClass p = new myInnerClass(a, b);
    p.myMethod();  //this will also work since c is defined in myOuterClass
  class myInnerClass{
    A a;
    B b;
    myInnerClass(A a, B b){
      this.a = a;
      this.b = b;
    public void myMethod(){
      c.doSomething(a, b);
}Note: this example is supplied off the top of my head without being tried in my IDE, but should show the concepts even if my fat fingers have hit the wrong keys.