Java Tutorial 1 20041021 Java Resource Java SDK

Java Tutorial 1 2004/10/21

Java Resource • Java SDK – Download from http: //www. javasoft. com – Install • Jdk-1. 5. 0 -windows-i 586. exe – 設定環境變數 • Set classpath=c: program filesjavajdk 1. 5. 0libtools. jar; c; examplelibexample. jar; . • Set Path=c: program filesjavajdk-1. 5. 0 – 測試 • Javac

Java Program • Require – Program Editor • Notepad • Ultra. Edit • 可以編輯文字的編輯器都可以 – 檔案名稱需要與 Class 名稱相同(注意大小寫) – 副檔名需儲存為. java – J 2 SE 5. 0 Documentation • Java 2 Platform API Specification

Example • Like C Example -------------------------------public class for. Loop { public static void main(String args[]) { for (int count=0; count<10; count++) { Systm. out. println (“count=“+count); } } } --------------------------------

Example(1) • for. Loop. java – Class name is “for. Loop”, 將 for. Loop class 儲存成 for. Loop. java – public static void main(args[]) 是程式執行的進入點 – for (int count=0; count<10; count++) { • 需要使用變數時才宣告 • Compile – Javac for. Loop. java – 產生 for. Loop. class 的可執行 byte code • Run – Java for. Loop

Java Example(2) public class for. Loop 2 { public static void main(String args[]) { for (int count=0; count<10; count++) { Systm. out. println (“count=“+count); } System. out. println (“”); for (int count=0; count<10; count++) { Systm. out. println (“count=“+count); } } } – Save class as “for. Loop 2. java”

Java Standard Output • System. out – System. out. print(); – System. out. println(); • System. out. printf() – J 2 SE 5. 0支援, 可寫跟 C 一樣的printf方式輸出

Java Input public class Java. Input { public static void main(String args[]) { If (args. length>0) { System. out. println (args[0]); System. out. println (args[1]); System. out. println (args[2]); } } } • Java使用args陣列來接收外部的輸入參數 – Javac Java. Input. java – Java. Input I am here • 輸出 I am here • 小於三個輸入會有錯誤

Course Example public class String. Match { private String source; public void match(String taget) { for (int count=0; count<source. length(); count++) { If (target. equals(source. substring(count, count+target. length()) { System. out. println (target); } } } public void set. Source(String source) { this. source=source; } public static void main(String args[]) { String. Match stm=new String. Match(); stm. set. Source(“abcabc”); stm. match(“cab”); } }

Course Example(2) public class String. Match { private String source; public void match(String taget) { for (int count=0; count<source. length(); count++) { If (target. equals(source. substring(count, count+target. length()) { System. out. println (target); } } } public void set. Source(String source) { this. source=source; } public static void main(String args[]) { String. Match stm=new String. Match(); stm. set. Source(“abcabc”); stm. match(args[0]); } }