CPSC 210
B4: Data Flow
Learning Goals
-
You need to be able to determine the value of a variable…
- by reading code, and using the debugger
- by tracing the value passed into a method
- by tracing the value returned by a method
- by determining if there are duplicate references to the same object
- by understanding the scope of variables
Lecture Ticket Review
public class Person {
private int age;
public Person() {
this.age = 1;
}
public int getAge() {
return age;
}
public void getOlderByYears(int years) {
this.age = this.age + years;
years = years + 1;
// POINT A
}
}
public class Main {
public static void main(String[] args) {
Person jean = new Person();
int ageAmount = 3;
//POINT B
jean.getOlderByYears(ageAmount);
//POINT C
}
}public class Person {
private int age;
public Person() {
this.age = 1;
}
public int getAge() {
return age;
}
public void getOlderByYears(int years) {
this.age = this.age + years;
years = years + 1;
// POINT A
}
}
public class Main {
public static void main(String[] args) {
Person jean = new Person();
int ageAmount = 3;
//POINT B
jean.getOlderByYears(ageAmount);
//POINT C
}
}Q1
public class Person {
private int age;
public Person() {
this.age = 1;
}
public int getAge() {
return age;
}
public void getOlderByYears(int years) {
this.age = this.age + years;
years = years + 1;
// POINT A
}
}
public class Main {
public static void main(String[] args) {
Person jean = new Person();
int ageAmount = 3;
//POINT B
jean.getOlderByYears(ageAmount);
//POINT C
}
}Q2
public class Person {
private int age;
public Person() {
this.age = 1;
}
public int getAge() {
return age;
}
public void getOlderByYears(int years) {
this.age = this.age + years;
years = years + 1;
// POINT A
}
}
public class Main {
public static void main(String[] args) {
Person jean = new Person();
int ageAmount = 3;
//POINT B
jean.getOlderByYears(ageAmount);
//POINT C
}
}Q3
public class Person {
private int age;
public Person() {
this.age = 1;
}
public int getAge() {
return age;
}
public void getOlderByYears(int years) {
this.age = this.age + years;
years = years + 1;
}
public void copyInto(Person other) {
other = this;
}
}
public class Main {
public static void main(String[] args) {
Person jean = new Person();
Person manon = new Person();
jean.getOlderByYears(10);
jean.copyInto(manon);
System.out.println(manon.getAge());
}
}BONUS: Q4
What does this print?
We asked what happens to the argument when we reassign a parameter's value. Which is the answer?
- Nothing, if it's of a primitive type rather than a reference to an object.
- Nothing, because the parameter's value is in its own space in memory.
Lecture Lab
Please select an option (plus or quit):
plus
you selected: plus
Please enter the first number to plus
6
Please enter the second number to plus
2
that equals: 0
Please select an option (plus or quit):
plus
you selected: plus
Please enter the first number to plus
8
Please enter the second number to plus
5
that equals: 0
Please select an option (plus or quit):
plus
you selected: plus
Please enter the first number to plus
12
Please enter the second number to plus
32
that equals: 0
Please select an option (plus or quit):
quit
you selected: quit
Operation log: [
plus [6, 2, 8, 5, 12, 32] equals 44,
plus [6, 2, 8, 5, 12, 32] equals 44,
plus [6, 2, 8, 5, 12, 32] equals 44]
plus[6,2] equals 8, plus [8,5] equals 13...Expected:
Extra: Git Branching
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