Variables and Data Types

Jython uses the same Python data types you know - int, float, string, list, dict, tuple, boolean - with the same dynamic typing: variables are names bound to values, and types are a property of values, not declarations. On top of that, Java types are first-class values you can create and manipulate.

Python Data Types

x = 42              # int
y = 3.14            # float
s = "Skillversitas" # str
t = (1, 2, 3)       # tuple
lst = [1, 2, 3]     # list
d = {"a": 1}        # dict
flag = True         # bool
print(type(x), type(s), type(lst))

Conversion Functions

print(int("42"))        # 42
print(float("3.14"))    # 3.14
print(str(42))          # "42"
print(int("0xFF", 16))  # 255
print(hex(255))         # 0xff

Java Types in Jython

Instantiate Java classes with their constructors and call methods normally:

import java.lang

i = java.lang.Integer(42)
print(i.intValue())
print(i + 1)          # Jython auto-converts to Python int arithmetic

s = java.lang.String("hello")
print(s.length())     # Java method call

# strings interoperate: Python str and java.lang.String convert automatically
print(len(s))

Number Interoperability

Variable Rules (Same as Python)

• No declarations: x = 10 binds the name.
• Names are case-sensitive; start with a letter or underscore.
• Assignment creates or rebinds; there are no type annotations (Jython 2.7 has none).
• Use help(type) and dir() to inspect any object, Python or Java.

Summary

Jython variables follow normal Python rules - dynamic typing, no declarations, conversion via int/float/str - and additionally accept Java objects like java.lang.Integer and java.lang.String as first-class values. Numbers and strings interoperate automatically between the two type systems, which is what makes mixing Python and Java painless.