VB Java VB Module 1 Sub Main Dim

從 VB 到 Java / 物件導向程式設計 簡單的 VB 程式 Module 1 Sub Main() Dim in 1, in 2, out As Integer in 1 = Val(Console. Read. Line()) in 2 = Val(Console. Read. Line()) out = in 1 + in 2 Console. Write. Line(out) End Sub End Module clchen@CJCU / 3

從 VB 到 Java / 物件導向程式設計 範例說明 Dim a = b = c = a, b, c As Integer 10 4 * 5 a b + c b * 2 2000 - a * b b a 20 40 記憶體 10 30 c 800 10 clchen@CJCU / 8

從 VB 到 Java / 物件導向程式設計 簡單的 Java 程式 public class Simple. Example { public static void main(String[] args) { int in 1, in 2, out; in 1 = Integer. parse. Int(System. console(). read. Line()); in 2 = Integer. parse. Int(System. console(). read. Line()); out = in 1 + in 2; System. out. println(out); Module 1 Sub Main() } Dim in 1, in 2, out As Integer } in 1 = Val(Console. Read. Line()) in 2 = Val(Console. Read. Line()) out = in 1 + in 2 Console. Write. Line(out) End Sub clchen@CJCU / 11 End Module

從 VB 到 Java / 物件導向程式設計 變數宣告敘述 int in 1, in 2, out; l int in 1 = 3, in 2 = 5, out; l l Java 型態 n strongly-typed：變數以及運算式的型態，編譯時就需固定 n 基本型態 (primitive type) byte (8), short (16), int (32), long (64) u float (32), double (64) u boolean u true, false u char (16) u 可以存 Unicode，或視為無正負號的整數 u n 參考型態 (reference type) u class-type, interface-type, array-type clchen@CJCU / 13

從 VB 到 Java / 物件導向程式設計 Java 文字數值 (literal)：原始程式內，表現數值的字串 整數文字數值 (integer literal) n int: 123, 0173, 0 X 7 B, 0 x 7 b n long: 123 L, 0173 L, 0 X 7 BL, 0 x 7 bl l 浮點數文字數值 (floating-point literal) n double: 1. 2, 1. 2 E 3, 1. 2 e-3 1. 2 D, 1. 2 E 3 D, 1. 2 e-3 d n float: 1. 2 F, 1. 2 E 3 F, 1. 2 e-3 f l 布林文字數值 (boolean literal) n true, false l 字元文字數值 (character literal) n 'C', '長', 'u 9577' l 字串文字數值 (string literal) n "CJCU is 長榮大學", "長", "'"\tn" l 空文字數值 (null literal) n null l l clchen@CJCU / 15

從 VB 到 Java / 物件導向程式設計 Java 運算式 l l l l 15 L postfix operators 14 R unary operators 13 R creation or cast 12 L multiplicative 11 L additive 10 L shift 9 L relational 8 L equality 7 L bitwise AND 6 L bitwise exclusive OR 5 L bitwise inclusive OR 4 L logical AND 3 L logical OR 2 L conditional 1 R assignment 優先次序 左/右關聯 []. (params) expr++ expr-++expr --expr +expr -expr ~ ! new (type)expr * / % + << >> >>> < > <= >= instanceof == != & ^ 可以加上分號 | 當成敘述 && || ? : = += -= *= /= %= &= ^= |= <<= >>>= clchen@CJCU / 16