初学JAVA

发现自己搞了个笑话

public class Class_one {
 public String str = "one";
 protected String getNumber() {
  return str;
 }
 public static void main(String args[]) {
  Class_one a = new Class_one();
  System.out.println(a.getNumber());
 }
}
public class Class_two extends Class_one {
 public String str = "two";
 protected String getNumber() {
  return super.str;
 }
 public static void main(String args[]) {
  Class_two b = new Class_two();
  System.out.println(b.getNumber());
 }
}

public class Class_three extends Class_two {
 public String str = "three";
 protected String getNumber() {
  return super.str;
 }
 public static void main(String args[]) {
  Class_three c = new Class_three();
  System.out.println(c.getNumber());
 }
}
问题：Class_three 中的getNumber()可以不override么？为什么？

public class Class_one {
 private String str = "one";
 protected String getNumber() {
  return str;
 }
 public static void main(String args[]) {
  Class_one a = new Class_one();
  System.out.println(a.getNumber());
 }
}
public class Class_two extends Class_one {
 private String str = "two";
 protected String getNumber() {
  return super.getNumber();
 }
 public static void main(String args[]) {
  Class_two b = new Class_two();
  System.out.println(b.getNumber());
 }
}

public class Class_three extends Class_two {
 private String str = "three";
 protected String getNumber() {
  return super.getNumber();
 }
 public static void main(String args[]) {
  Class_three c = new Class_three();
  System.out.println(c.getNumber());
 }
}
这样呢？
结果有什么区别？

呵呵