Sun Xin's first lesson in Java

 

Public class welcome {public static void main (string [] ARGs) {// system. out. print ("Restoration: http://www.mybole.com.cn \ n"); // system. out. println ("welcome you! ");/* Byte B; B = 3; B = (byte) (B * 3); system. out. println (B); * // short S;/* int I; long l; * // * char ch; CH = 97; system. out. println (CH); * // * float F; F = 1.3f; system. out. println (f); * // double D;/* Boolean bool; bool = true; system. out. println (bool); * // * If (true) {} * // int num [] = new int [3];/* int [] num; num = {1, 2, 3}; // Error * // int [] num1; // int [] num2; // num = new int [3]; // int [] num = new int [] {1, 2, 3}; // OK // int [] num = new int [3] {1, 2, 3 }; // error;/* int [] num; num = new int [3]; num [0] = 1; num [1] = 12; num [2] = 32; system. out. println (Num [0]); system. out. println (Num [1]); system. out. println (Num [2]); * // * int [] [] num; num = new int [3] [4]; num [0] [1] = 12; num [2] [3] = 34; * // * int [] [] num; num = new int [3] []; num [0] = new int [5]; num [1] = new int [3]; num [2] = new int [2]; num [0] [4] = 45; num [1] [2] = 34; num [2] [1] = 21; system. out. println (Num [0] [4]); system. out. println (Num [1] [2]); system. out. println (Num [2] [1]); system. out. println (Num [2] [2]); * // int [] [] num = new int [] [] {1, 2, 3, 4, 5 }; // error // int [] [] num = new int [] [] {1, 2, 3}, {4, 5 }}; // OK // int [] [] num = new int [2] [] {1, 2}, {4, 5 }}; // error // int [] [] num = {1, 2, 3}, {4, 5, 6 }}; // OK/* int [] [] num = {1, 2, 3}, {4, 5}, {6}; system. out. println (Num [0] [2]); system. out. println (Num [1] [1]); system. out. println (Num [2] [0]); * // * int I = 3; // system. out. println (I ++); system. out. println (++ I); * // * int I = 3; // int COUNT = (I ++) + (I ++ ); int COUNT = (++ I) + (++ I); system. out. println (I); system. out. println (count); */If () {} while (true) {} do {} while (true); For (INT I = 0; I <10; I ++ ){}}}