Last login: Sun Oct 25 08:48:03 on ttys004

The default interactive shell is now zsh.
To update your account to use zsh, please run `chsh -s /bin/zsh`.
For more details, please visit https://support.apple.com/kb/HT208050.
(base) MAC:Mon Oct 26:09:20:4240> B
(base) MAC:Mon Oct 26:09:20:4240> jshell
|  Welcome to JShell -- Version 14.0.1
|  For an introduction type: /help intro

jshell> ArrayList<int> al = new ArrayList<>();
|  Error:
|  unexpected type
|    required: reference
|    found:    int
|  ArrayList<int> al = new ArrayList<>();
|            ^-^

jshell> ArrayList<Integer> al = new ArrayList<>();
al ==> []

jshell> for(int k = 0; k < 20; k++){al.add(k*k*k);}

jshell> al
al ==> [0, 1, 8, 27, 64, 125, 216, 343, 512, 729, 1000, 1331, 1728, 2197, 2744, 3375, 4096, 4913, 5832, 6859]

jshell> String s = "foo";
s ==> "foo"

jshell> Integer i = 5;
i ==> 5

jshell> //autoboxing

jshell> i.getClass()
$6 ==> class java.lang.Integer

jshell> int x = 42;
x ==> 42

jshell> x.getClass()
|  Error:
|  int cannot be dereferenced
|  x.getClass()
|  ^--------^

jshell> x = i;
x ==> 5

jshell> 

jshell> //autounboxing

jshell> out = 0;
|  Error:
|  cannot find symbol
|    symbol:   variable out
|  out = 0;
|  ^-^

jshell> int out = 17;
out ==> 17

jshell> for(Integer i = 0; i < 5000; i++){out += i;}

jshell> out
out ==> 12497517

jshell> String quack = "531";
quack ==> "531"

jshell> //can you figure out how to get 531 out of this?

jshell> Integer.parseInt(quack)
$13 ==> 531

jshell> Integer.parseInt("duck egg")
|  Exception java.lang.NumberFormatException: For input string: "duck egg"
|        at NumberFormatException.forInputString (NumberFormatException.java:68)
|        at Integer.parseInt (Integer.java:652)
|        at Integer.parseInt (Integer.java:770)
|        at (#14:1)

jshell> /exit
|  Goodbye
(base) MAC:Mon Oct 26:09:44:4240> vi Exceptional.java
(base) MAC:Mon Oct 26:09:46:4240> javac Exceptional.java 
(base) MAC:Mon Oct 26:09:46:4240> java Exceptional
I am now alive and on
the correct side of the weeds
445
Exception in thread "main" java.lang.NumberFormatException: For input string: "duck egg"
    at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
    at java.base/java.lang.Integer.parseInt(Integer.java:652)
    at java.base/java.lang.Integer.parseInt(Integer.java:770)
    at Exceptional.main(Exceptional.java:9)
(base) MAC:Mon Oct 26:09:46:4240> !vi
vi Exceptional.java
(base) MAC:Mon Oct 26:09:48:4240> javac Exceptional.java
Exceptional.java:12: error: variable al might not have been initialized
       al.add("foo");
       ^
1 error
(base) MAC:Mon Oct 26:09:49:4240> !vi
vi Exceptional.java
(base) MAC:Mon Oct 26:09:49:4240> !javac
javac Exceptional.java
Note: Exceptional.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
(base) MAC:Mon Oct 26:09:49:4240> java Exceptional
I am now alive and on
the correct side of the weeds
445
Exception in thread "main" java.lang.NullPointerException
    at Exceptional.main(Exceptional.java:12)
(base) MAC:Mon Oct 26:09:49:4240> !vi
vi Exceptional.java
(base) MAC:Mon Oct 26:09:50:4240> jshell
|  Welcome to JShell -- Version 14.0.1
|  For an introduction type: /help intro

jshell> //what is 1000 in base 8?

jshell> Integer.toOctalString(1000)
$1 ==> "1750"

jshell> //what is 1000 in base 3?

jshell> Integer.toHexString(1000)
$2 ==> "3e8"

jshell> Integer.parseInt("1010111", 2)
$3 ==> 87

jshell> Integer.toString(1000, 3)
$4 ==> "1101001"

jshell> Integer.toString(1001, 3)
$5 ==> "1101002"

jshell> s = "true"
|  Error:
|  cannot find symbol
|    symbol:   variable s
|  s = "true"
|  ^

jshell> String s = "true"
s ==> "true"

jshell> Boolean.parseBool(s)
|  Error:
|  cannot find symbol
|    symbol:   method parseBool(java.lang.String)
|  Boolean.parseBool(s)
|  ^---------------^

jshell> Boolean.parseBoolean(s)
$7 ==> true

jshell> Boolean.toString(true)
$8 ==> "true"

jshell> "" + true
$9 ==> "true"

jshell> String guac = "6.02e23"
guac ==> "6.02e23"

jshell> double avocado = Double.parseDouble(guac)
avocado ==> 6.02E23

jshell> Character.isDigit('7')
$12 ==> true

jshell> Character.isDigit('q')
$13 ==> false

jshell> Character.BYTES
$14 ==> 2

jshell> Integer.BYTES
$15 ==> 4

jshell> Long.BYTES
$16 ==> 8

jshell> Character c = 'q'
c ==> 'q'

jshell> (int) q
|  Error:
|  cannot find symbol
|    symbol:   variable q
|  (int) q
|        ^

jshell> (int) c
$18 ==> 113

jshell> Character.isAlphabetic('5')
$19 ==> false

jshell> Character.isAlphabetic('a')
$20 ==> true

jshell> Character.isAlphabetic('A')
$21 ==> true

jshell> Character.isUpper('A')
|  Error:
|  cannot find symbol
|    symbol:   method isUpper(char)
|  Character.isUpper('A')
|  ^---------------^

jshell> Character.isUpperCase('A')
$22 ==> true

jshell> for(char c = 'A'; c <= 'z'; c++){System.out.printf("%s:  isLetter: %s\n", c, Character.isLetter(c));}
A:  isLetter: true
B:  isLetter: true
C:  isLetter: true
D:  isLetter: true
E:  isLetter: true
F:  isLetter: true
G:  isLetter: true
H:  isLetter: true
I:  isLetter: true
J:  isLetter: true
K:  isLetter: true
L:  isLetter: true
M:  isLetter: true
N:  isLetter: true
O:  isLetter: true
P:  isLetter: true
Q:  isLetter: true
R:  isLetter: true
S:  isLetter: true
T:  isLetter: true
U:  isLetter: true
V:  isLetter: true
W:  isLetter: true
X:  isLetter: true
Y:  isLetter: true
Z:  isLetter: true
[:  isLetter: false
\:  isLetter: false
]:  isLetter: false
^:  isLetter: false
_:  isLetter: false
`:  isLetter: false
a:  isLetter: true
b:  isLetter: true
c:  isLetter: true
d:  isLetter: true
e:  isLetter: true
f:  isLetter: true
g:  isLetter: true
h:  isLetter: true
i:  isLetter: true
j:  isLetter: true
k:  isLetter: true
l:  isLetter: true
m:  isLetter: true
n:  isLetter: true
o:  isLetter: true
p:  isLetter: true
q:  isLetter: true
r:  isLetter: true
s:  isLetter: true
t:  isLetter: true
u:  isLetter: true
v:  isLetter: true
w:  isLetter: true
x:  isLetter: true
y:  isLetter: true
z:  isLetter: true

jshell> 

jshell> Character.isSpace(" ")
|  Error:
|  incompatible types: java.lang.String cannot be converted to char
|  Character.isSpace(" ")
|                    ^-^

jshell> Character.isSpace(' ')
$24 ==> true

jshell> Character.isSpace('\n')
$25 ==> true

jshell> Character.isSpace('\t')
$26 ==> true

jshell> Integer.MAX_VALUE
$27 ==> 2147483647

jshell> Integer.MIN_VALUE
$28 ==> -2147483648

jshell> Double.MAX_VALUE
$29 ==> 1.7976931348623157E308

jshell> Double.isFinite(5)
$30 ==> true

jshell> Double.isFinite(1.0/0)
$31 ==> false

jshell> Double.isNaN(1.0/0)
$32 ==> false

jshell> 1.0/0
$33 ==> Infinity

jshell> Double.SIZE
$34 ==> 64

jshell> Double.BYTES
$35 ==> 8

jshell>