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

jshell> Double d = 3.44;
d ==> 3.44

jshell> d
d ==> 3.44

jshell> i.getClass()
$4 ==> class java.lang.Integer

jshell> int k = 5;
k ==> 5

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

jshell> double primitive = d;
primitive ==> 3.44

jshell> //autobox:  assign wrapper type variable to primitive

jshell> //autounbox asssign wrapper object to primitive

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

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

jshell> nums.add(42);
$8 ==> true

jshell> nums
nums ==> [42]

jshell> nums.add(44);
$10 ==> true

jshell> nums.add(10);
$11 ==> true

jshell> nums
nums ==> [42, 44, 10]

jshell> ArrayList<Boolean> foo = new ArrayList<>();
foo ==> []

jshell> foo.add(false);
$14 ==> true

jshell> foo.add(true);
$15 ==> true

jshell> foo.add(17);
|  Error:
|  incompatible types: int cannot be converted to java.lang.Boolean
|  foo.add(17);
|          ^^

jshell> TreeSet<Integer> ts = new TreeSet<>();
ts ==> []

jshell> ts.add(5);
$17 ==> true

jshell> 

jshell> ts.add(5)
$18 ==> false

jshell> ts.add(-1)
$19 ==> true

jshell> ts.add(45);
$20 ==> true

jshell> ts
ts ==> [-1, 5, 45]

jshell> ts.add(88)
$22 ==> true

jshell> ts
ts ==> [-1, 5, 45, 88]

jshell> //tree sets require orderable objects

jshell> Tree<Boolean> ts = new TreeSet<>();
|  Error:
|  cannot find symbol
|    symbol:   class Tree
|  Tree<Boolean> ts = new TreeSet<>();
|  ^--^

jshell> TreeSet<Boolean> ts = new TreeSet<>();
ts ==> []

jshell> ts.add(true)
$25 ==> true

jshell> ts
ts ==> [true]

jshell> ts.add(false);
$27 ==> true

jshell> ts
ts ==> [false, true]

jshell> ts.add(true)
$29 ==> false

jshell> ts
ts ==> [false, true]

jshell> Integer q = 5;
q ==> 5

jshell> Integer r = 6;
r ==> 6

jshell> q < r
$33 ==> true

jshell> q.compareTo(r) < 0
$34 ==> true

jshell> Integer.compare(5,6)
$35 ==> -1

jshell> Integer.compare(5,6) < -
   ...> 0
$36 ==> true

jshell> Integer.decode("0xFF")
$37 ==> 255

jshell> Integer.decode("0o66")
|  Exception java.lang.NumberFormatException: For input string: "o66" under radix 8
|        at NumberFormatException.forInputString (NumberFormatException.java:67)
|        at Integer.parseInt (Integer.java:668)
|        at Integer.valueOf (Integer.java:973)
|        at Integer.decode (Integer.java:1458)
|        at (#38:1)

jshell> Integer.decode("066")
$39 ==> 54

jshell> Integer.decode("0b1110101010101");
|  Exception java.lang.NumberFormatException: For input string: "b1110101010101" under radix 8
|        at NumberFormatException.forInputString (NumberFormatException.java:67)
|        at Integer.parseInt (Integer.java:668)
|        at Integer.valueOf (Integer.java:973)
|        at Integer.decode (Integer.java:1458)
|        at (#40:1)

jshell> 0b11010110101
$41 ==> 1717

jshell> 0xFF
$42 ==> 255

jshell> 0o66
|  Error:
|  ';' expected
|  0o66
|   ^

jshell> 066
$43 ==> 54

jshell> Math.max(5,6)
$44 ==> 6

jshell> Integer i = Math.max(5,6);
i ==> 6

jshell> Integer.parseInt("31434")
$46 ==> 31434

jshell> Integer.parseInt("abcdef", 16)
$47 ==> 11259375

jshell> Integer.parseInt("1011011110", 2)
$48 ==> 734

jshell> Integer.parseInt("202221112", 3)
$49 ==> 15269

jshell> String quack = "4.2356"
quack ==> "4.2356"

jshell> Double.parseDouble(quack)
$51 ==> 4.2356

jshell> Double.parseDouble("6.20e23")
$52 ==> 6.2E23

jshell> Boolean.parseBoolean("false")
$53 ==> false

jshell> //Type.parseType(string) -> object of type type

jshell> Integer.sgn(5)
|  Error:
|  cannot find symbol
|    symbol:   method sgn(int)
|  Integer.sgn(5)
|  ^---------^

jshell> Integer.signum(5)
$54 ==> 1

jshell> Integer.signum(100)
$55 ==> 1

jshell> Integer.signum(1000)
$56 ==> 1

jshell> Integer.signum(0)
$57 ==> 0

jshell> Integer.signum(-42)
$58 ==> -1

jshell> Integer.toHexString(100)
$59 ==> "64"

jshell> Integer.toHexString(1023)
$60 ==> "3ff"

jshell> Integer.toHexString(1023).toUpperCase()
$61 ==> "3FF"

jshell> Integer.toString(2314431)
$62 ==> "2314431"

jshell> "" + 2314431
$63 ==> "2314431"

jshell> Integer.toString(2314431, 16)
$64 ==> "2350bf"

jshell> Integer.toString(2314431, 36)
$65 ==> "1dltr"

jshell> Integer.MAX_VALUE
$66 ==> 2147483647

jshell> Long.MAX_VALUE
$67 ==> 9223372036854775807

jshell> Float.MAX_VALUE
$68 ==> 3.4028235E38

jshell> Double.MAX_VALUE
$69 ==> 1.7976931348623157E308

jshell> Integer.SIZE
$70 ==> 32

jshell> Short.SIZE
$71 ==> 16

jshell> Double.SIZE
$72 ==> 64

jshell> Boolean.SIZE
|  Error:
|  cannot find symbol
|    symbol:   variable SIZE
|  Boolean.SIZE
|  ^----------^

jshell> Boolean.valueOf("cow")
$73 ==> false

jshell> Boolean.toString(false)
$74 ==> "false"

jshell> "" + false
$75 ==> "false"

jshell>