这个属于基础知识:
表达的意思也就是标题的意思,
eg:

public class Father {
  private FatherF fatherF = new FatherF();
//

  public Father() {
    System.out.println("new father");
  }
}

public class FatherF {
  public FatherF() {
    System.out.println("new father field");
  }
}

class Son extends Father{
  private SonF fatherF = new SonF();
  public Son() {
    System.out.println("new son");
  }
}

public class SonF {
  public SonF() {
    System.out.println("new son field");
  }
}

示例:

public class NewObject {
  public static void main(String[] args) {
    Son son = new Son();
  }
}