Test02

 

Class: 1st i          Name : ___________________________________________________________________________________________

 

Question 01
What is an instance variable?

Answer:  _______________________________________________________________________________________________________________________

_______________________________________________________________________________________________________________________________

_______________________________________________________________________________________________________________________________

 

Question 02
Below is a class, MobilePhone, to represent a mobile phone. It holds two instance variables, phoneNumber (a String) and PINcode (an int). For phoneNumber there is an accessor (getter) and a mutator (setter) called getPhoneNumber() and setPhoneNumber().

You should create the accessor and mutator for PINcode. Please fill in the code after the comments in the class below!

class MobilePhone {

   /** Creates a new instance of MobilPhone with default values
    */
   public MobilePhone() {
      this.phoneNumber = "No number set!";
      this.PINcode = 1234;
   }

   /** Creates a new instance of MobilPhone with values from parameters
    * @param phoneNumber the number for the phone
    * @param PINcode an integer to unlock the phone
    */
   public MobilePhone(String phoneNumber, int PINcode) {
      this.phoneNumber = phoneNumber;
      this.PINcode = PINcode;
   }

   /** Sets (overwrites) the value for the phoneNumber
    * @param phoneNumber the new value for the phoneNumber
    */
   public void setPhoneNumber(String phoneNumber) {
      this.phoneNumber = phoneNumber;
   }

   /** Reads and returns the value for the phoneNumber
    */   
   public String getPhoneNumber() {
      return phoneNumber;
   }

   /** Sets (overwrites) the value for the phoneNumber
    * @param phoneNumber the new value for the phoneNumber
    */

 

 

 

   /** Reads and returns the value for the phoneNumber
    */

 

 

 

   private String phoneNumber;
   private int PINcode;
}

Question 03
Show how the method toString() could be implemented for the class MobilePhone (see above):

 

Question 04
Assume that the String variable st holds the value “My mom is sweet”.

What is the value of len after the expression int len = st.length(); has been executed?

Answer: __________________________________________________________

 

What is the value of st.substring(1,5)?

Answer: __________________________________________________________

 

What is the value of st.substring(7);

Answer: __________________________________________________________

 

Question 05
Assume that the following lines are executed:

int age = 12;
int heigth = 140;

What will be printed on the screen after the following lines of code has been executed?

   if (age > 12)
      System.out.println(“Statement 01”);
   else
   if ((heigth > age) && (age != 13)) {
      System.out.println(“Statement 02”);
   }
   else
      System.out.println(“Statement 03”);
      System.out.println(“Statement 04”);

 

Answer: __________________________________________________________

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