1. ã¯ããã«
ããã°ã©ãã³ã°ã®äžçã«ã¯å€ãã®èšèªãååšããŸããããã®äžã§ãç¹ã«æ³šç®ãããŠããã®ãJavaã§ãããã®ã»ã¯ã·ã§ã³ã§ã¯ãJavaãã©ã®ãããªèšèªã§ããã®ãããããŠJavaãåŠã¶ã¡ãªããã«ã€ããŠè§£èª¬ããŸãã
1.1 Javaãšã¯
Javaã¯ã1990幎代åé ã«Sun Microsystemsã«ãã£ãŠéçºãããããã°ã©ãã³ã°èšèªã§ãããªããžã§ã¯ãæåããã°ã©ãã³ã°ãåºç€ãšããŠãããäžåºŠæžããã³ãŒããããŸããŸãªãã©ãããã©ãŒã ã§åäœãããWrite Once, Run Anywhereããã³ã³ã»ãããšããŠããŸããJavaã®æ倧ã®ç¹åŸŽã¯ãJVMïŒJava Virtual MachineïŒäžã§åäœããããšã§ããããã«ãããWindowsãMacãLinuxãªã©ãããŸããŸãªOSäžã§åãJavaã®ã³ãŒããåäœããããšãå¯èœãšãªããŸããã
1.2 ãªãJavaãåŠã¶ã®ã
JavaãåŠã¶çç±ã¯ããã€ããããŸãããŸããå€æ§æ§ã§ããJavaã¯å€ãã®åéã§äœ¿çšãããŠãããããJavaãç¿åŸããããšã§ããŠã§ãéçºããã¹ããŒããã©ã³ã¢ããªãããŒã¿ããŒã¹ã®æäœãªã©ãããŸããŸãªãããžã§ã¯ãã«åãçµãããšãã§ããŸãã
次ã«ãæ±äººåžå Žã®éèŠã§ããJavaã®ã¹ãã«ã¯ãITæ¥çã«ãããŠåžžã«é«ãéèŠããããŸããå€ãã®äŒæ¥ãJavaãæ¡çšããŠãããããJavaã®ã¹ãã«ãæã£ãŠãããšãå°±è·ã転è·ã®éã«æå©ãšãªãããšãå€ãã§ãã
ãŸããJavaã¯ã³ãã¥ããã£ãéåžžã«æŽ»çºã§ãããããåŠç¿äžã«å°ã£ãéã«è³ªåãããå Žããæ°ããæ å ±ãåŸãããã®ãªãœãŒã¹ãè±å¯ã«ãããŸããããã«ãããèªåäžäººã§åŠã¶éã§ãããµããŒããåããªããå¹ççã«åŠç¿ãé²ããããšãã§ããŸãã
2. Javaç¬åŠã¬ã€ã: å¹ççãªåŠã³æ¹
Javaã¯ãã®å€æ§æ§ãšæ±çšæ§ãããåå¿è ã«ãšã£ãŠåŠã³ãããèšèªã®äžã€ãšãããŠããŸãããããããã®åŠã³æ¹ã«ã¯ã³ããå¿ èŠã§ãããã®ã»ã¯ã·ã§ã³ã§ã¯ãJavaã®åºæ¬çãªæ§æãããŒã¿åãå¶åŸ¡æ§æã«ã€ããŠãå¹ççã«åŠã¶ããã®ã¬ã€ããæäŸããŸãã
2.1 Javaã®åºæ¬æ§æ
Javaã®åºæ¬æ§æã¯ãä»ã®å€ãã®ããã°ã©ãã³ã°èšèªãšå ±éç¹ãå€ãã§ããæåã«åŠã¶ã¹ãã¯ãå€æ°ã®å®£èšãé¢æ°ã®å®çŸ©ããããŠã¯ã©ã¹ã®äœæã§ããJavaã§ã¯ããã¹ãŠã®ã³ãŒãã¯ã¯ã©ã¹å ã«èšè¿°ãããŸãããã®ã¯ã©ã¹ã®äžã«ãå€æ°ãé¢æ°ãå®çŸ©ããŠãããŸãã
äŸãã°ã”Hello, World!”ãšè¡šç€ºããããã°ã©ã ã¯ä»¥äžã®ããã«ãªããŸãã
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
ãã®ã³ãŒãã¯ãHelloWorldãšããã¯ã©ã¹ã®äžã«ãmainãšããé¢æ°ãå®çŸ©ããŠããŸãããããŠããã®é¢æ°ã®äžã§ãSystem.out.printlnãšããåœä»€ã䜿çšããŠãæååã衚瀺ããŠããŸãã
2.2 Javaã®ããŒã¿åãšå€æ°
Javaã«ã¯ãããŸããŸãªããŒã¿åãååšããŸãããããã®ããŒã¿åãç解ããããšã§ãå€æ°ãå¹æçã«äœ¿çšããããšãã§ããŸããäž»ãªããŒã¿åã«ã¯ãintïŒæŽæ°ïŒãdoubleïŒæµ®åå°æ°ç¹æ°ïŒãcharïŒæåïŒãbooleanïŒçåœå€ïŒãªã©ããããŸãã
å€æ°ã®å®£èšã¯ãããŒã¿åã®åŸã«å€æ°åãèšè¿°ããããšã§è¡ããŸããäŸãã°ãæŽæ°ãæ ŒçŽããå€æ°ã宣èšããå Žåã¯ã以äžã®ããã«èšè¿°ããŸãã
int number = 10;
ãã®ããã«ãintãšããããŒã¿åã®åŸã«ãnumberãšããå€æ°åãèšè¿°ããŠããã®å€æ°ã«10ãšããå€ãä»£å ¥ããŠããŸãã
2.3 å¶åŸ¡æ§æãšã«ãŒã
å¶åŸ¡æ§æã¯ãããã°ã©ã ã®æµããå¶åŸ¡ããããã®æ§æã§ããäž»ãªå¶åŸ¡æ§æã«ã¯ãifæãswitchæããããŸãããŸããç¹°ãè¿ãã®åŠçãè¡ãããã®ã«ãŒãã«ã¯ãforæãwhileæããããŸãã
äŸãã°ãããæ¡ä»¶ãæç«ããå Žåã«ç¹å®ã®åŠçãè¡ãå Žåã¯ãifæã䜿çšããŸãã以äžã¯ãå€æ°numberã®å€ã10以äžã®å Žåã«ã”Number is greater than or equal to 10.”ãšè¡šç€ºããããã°ã©ã ã®äŸã§ãã
int number = 15;
if (number >= 10) {
System.out.println("Number is greater than or equal to 10.");
}
ãã®ããã«ãifã®åŸã«æ¡ä»¶ãèšè¿°ãããã®æ¡ä»¶ãæç«ããå Žåã«ãäžæ¬åŒ§{}ã®äžã®åŠçãå®è¡ãããŸãã
3. ãããããªãœãŒã¹äžèŠ§
Javaãå¹æçã«åŠã¶ããã«ã¯ãé©åãªãªãœãŒã¹ãå©çšããããšãäžå¯æ¬ ã§ãããã®ã»ã¯ã·ã§ã³ã§ã¯ããªã³ã©ã€ã³åŠç¿ãµã€ããåèæžç±ãå®è·µçãªãããžã§ã¯ãäŸã玹ä»ããJavaã®åŠç¿ããµããŒãããããã®æ å ±ãæäŸããŸãã
3.1 ãªã³ã©ã€ã³åŠç¿ãµã€ã
è¿å¹Žããªã³ã©ã€ã³äžã§ã®ããã°ã©ãã³ã°åŠç¿ãéåžžã«äººæ°ãéããŠããŸããç¹ã«Javaã«é¢ããŠã¯ãå€ãã®ãµã€ããåå¿è åãã®ã³ãŒã¹ãæäŸããŠããŸãã以äžã¯ããã®äžã§ãç¹ã«ããããã®ãµã€ããããã€ã玹ä»ããŸãã
Codecademy: ã€ã³ã¿ã©ã¯ãã£ããªåŠç¿ç°å¢ãæäŸããŠãããå®éã«ã³ãŒããæžããªããåŠã¶ããšãã§ããŸãã
LeetCode: åé¡è§£æ±ºã®ã¹ãã«ãé«ããããã®ãµã€ãã§ãJavaã䜿çšããããã°ã©ãã³ã°ã®åé¡ã解ãããšãã§ããŸãã
Coursera: 倧åŠã®è¬çŸ©ããªã³ã©ã€ã³ã§åè¬ã§ãããµã€ãã§ãJavaã®åºç€ããå¿çšãŸã§å¹ åºãåŠã¶ããšãã§ããŸãã
3.2 åèæžç±
æžç±ã¯ãæ·±ãç¥èãåŸãããã®åªãããªãœãŒã¹ã§ãã以äžã¯ãJavaã®åŠç¿ã«ç¹ã«ããããã®æžç±ãããã€ã玹ä»ããŸãã
ãEffective Javaã: Javaã®ãã¹ããã©ã¯ãã£ã¹ãåŠã¶ããã®å®çªæžç±ã§ãäžçŽè 以äžã®ãšã³ãžãã¢ã«ç¹ã«ããããã§ãã
ãJavaããã©ãŒãã³ã¹ã: Javaã®ããã©ãŒãã³ã¹ãã¥ãŒãã³ã°ã«é¢ãã詳现ãªæ å ±ãæäŸããŠããŸãã
3.3 å®è·µçãªãããžã§ã¯ãäŸ
å®éã«ãããžã§ã¯ããæãããããšã¯ãåŠãã ç¥èãå®è·µããæãå¹æçãªæ¹æ³ã§ãã以äžã¯ãJavaã®åŠç¿è ãåãçµããšè¯ãå®è·µçãªãããžã§ã¯ãã®äŸã玹ä»ããŸãã
Webã¢ããªã±ãŒã·ã§ã³ã®éçº: Javaã䜿çšãããŠã§ãã¢ããªã±ãŒã·ã§ã³ã®éçºã¯ãå€ãã®äŒæ¥ã§æ±ããããã¹ãã«ã§ããç¹ã«ãSpringãã¬ãŒã ã¯ãŒã¯ã䜿çšããéçºã¯ãçŸåšã®åžå Žã§éåžžã«äººæ°ããããŸãã
Androidã¢ããªã®éçº: Javaã¯ãAndroidã¢ããªã®éçºã«ã䜿çšãããŠããŸããç¬èªã®ã¢ããªãéçºããããšã§ãã¢ãã€ã«ã¢ããªã±ãŒã·ã§ã³ã®éçºã¹ãã«ãç¿åŸããããšãã§ããŸãã
ããŒã¿ããŒã¹ã®æäœ: Javaã䜿çšããŠããŒã¿ããŒã¹ãšã®é£æºãè¡ãã¹ãã«ã¯ãå€ãã®ã·ã¹ãã éçºã§å¿ èŠãšãããŸããSQLã®ç¥èãšçµã¿åãããããšã§ãããŒã¿ããŒã¹æäœã®ã¹ãã«ãé«ããããšãã§ããŸãã
4. Javaç¬åŠã®ã¹ã¹ã¡: åå¿è ããäžçŽè ãžã®éã®ã
Javaã®åŠç¿ã¯ãåå¿è ããäžçŽè ãŸã§ãããŸããŸãªæ®µéãååšããŸãããã®ã»ã¯ã·ã§ã³ã§ã¯ãããããã®æ®µéã§ã®åŠã³æ¹ã泚æç¹ãããã«äžãç®æãããã®ã¹ãã«ã»ããã«ã€ããŠè§£èª¬ããŸãã
4.1 åå¿è ãé¥ãããããã¹
Javaã®åŠç¿ãå§ããéãå€ãã®åå¿è ãé¥ãããããã¹ãããã€ãååšããŸããæãäžè¬çãªãã¹ã¯ãå€æ°ã®ã¹ã³ãŒãã®èª€è§£ãnullåç §ã®äŸå€ãããŒã¿åã®äžäžèŽãªã©ã§ãããããã®ãã¹ã¯ãåºæ¬çãªããã°ã©ãã³ã°ã®ç解ãäžè¶³ããŠããããšãåå ãšãªããŸãã
4.2 äžçŽè ãç®æããŠ
Javaã®åºæ¬çãªæ§æãããŒã¿åãç解ããåŸã次ã®ã¹ããããšããŠã¯ããªããžã§ã¯ãæåããã°ã©ãã³ã°ã®ç解ãæ·±ããããšãæšå¥šãããŸããJavaã¯ããªããžã§ã¯ãæåã匷ãæ¡çšããŠããèšèªã§ãããã¯ã©ã¹ãã€ã³ã¿ãŒãã§ãŒã¹ãç¶æ¿ãããªã¢ãŒãã£ãºã ãªã©ã®æŠå¿µããã£ãããšç解ããããšã§ãããé«åºŠãªããã°ã©ã ãæžãããšãã§ããŸãã
4.3 äžçŽè ã«ãªãããã®ã¹ãã«ã»ãã
Javaã®äžçŽè ãšããŠæŽ»èºããããã«ã¯ãããã«å¹ åºãç¥èãã¹ãã«ãæ±ããããŸããç¹ã«ããã¶ã€ã³ãã¿ãŒã³ã®ç解ãããã«ãã¹ã¬ããããã°ã©ãã³ã°ãããã©ãŒãã³ã¹ãã¥ãŒãã³ã°ãªã©ã®é«åºŠãªãã¯ããã¯ãç¿åŸããããšãéèŠã§ãã
5. Javaããã°ã©ãã³ã°ã®ãã¹ããã©ã¯ãã£ã¹
Javaããã°ã©ãã³ã°ã«ãããŠãé«å質ãªã³ãŒããæžãããã®ãã¹ããã©ã¯ãã£ã¹ã¯æ°å€ãååšããŸãããã®ã»ã¯ã·ã§ã³ã§ã¯ãã³ãŒãã®å質ãä¿ã€æ¹æ³ããå¹ççãªãããã°æè¡ãããã«ã¯ããã©ãŒãã³ã¹ã®æé©åã«ã€ããŠè§£èª¬ããŸãã
5.1 ã³ãŒãã®å質ãä¿ã€æ¹æ³
ã³ãŒãã®å質ã¯ãããã°ã©ã ã®å®å®æ§ãä¿å®æ§ã«çŽçµããŸããé«å質ãªã³ãŒããæžãããã«ã¯ã以äžã®ãããªæ¹æ³ãæšå¥šãããŸãã
ã³ãŒãã¬ãã¥ãŒ: ä»ã®éçºè ã«ã³ãŒããã¬ãã¥ãŒããŠãããããšã§ããã¹ãæ¹åç¹ãèŠã€ããããšãã§ããŸããç¹ã«ãçµéšè±å¯ãªéçºè ã®æèŠã¯éåžžã«äŸ¡å€ããããŸãã
åäœãã¹ã: ã³ãŒãã®åéšåãæ£ããåäœãããã確èªããããã®ãã¹ãã§ããJUnitãªã©ã®ãã¹ããã¬ãŒã ã¯ãŒã¯ã䜿çšããŠãèªååããããã¹ããå®æœããããšãæšå¥šãããŸãã
éçã³ãŒã解æ: ã³ãŒãã®å質ãèªåçã«è©äŸ¡ããããŒã«ã䜿çšããŠãæœåšçãªåé¡ç¹ãæ€åºããŸããäŸãã°ãSonarQubeãªã©ã®ããŒã«ããããŸãã
5.2 å¹ççãªãããã°æè¡
ããã°ã©ã ã«ã¯å¿ ããšèšã£ãŠããã»ã©ãã°ãçºçããŸããå¹ççãªãããã°æè¡ã身ã«ã€ããããšã§ãåé¡ã®åå ãè¿ éã«ç¹å®ããä¿®æ£ããããšãã§ããŸãã
ãã°ã®æŽ»çš: ããã°ã©ã ã®åäœããã°ã«åºåããããšã§ãåé¡ã®çºçç®æãåå ãç¹å®ãããããªããŸããJavaã§ã¯ãLog4jãSLF4Jãªã©ã®ãã°ã©ã€ãã©ãªãå©çšã§ããŸãã
ãããã¬ã®äœ¿çš: IDEã®ãããã¬ã䜿çšããããšã§ãã³ãŒãã®å®è¡ãäžæåæ¢ãããããå€æ°ã®å€ã確èªãããããããšãã§ããŸããããã«ããããã°ã®åå ãå¹ççã«ç¹å®ããããšãã§ããŸãã
5.3 ããã©ãŒãã³ã¹ã®æé©å
Javaããã°ã©ã ã®ããã©ãŒãã³ã¹ãæé©åããããã«ã¯ãããã€ãã®ãã¯ããã¯ãååšããŸãã
ãããã¡ã€ãªã³ã°: ããã°ã©ã ã®å®è¡äžã«ãã©ã®éšåãæãæéãæ¶è²»ããŠããããç¹å®ããããã®ããŒã«ã§ããJavaã§ã¯ãJProfilerãVisualVMãªã©ã®ãããã¡ã€ã©ãå©çšã§ããŸãã
ã¬ããŒãžã³ã¬ã¯ã·ã§ã³ã®æé©å: Javaã¯ã¬ããŒãžã³ã¬ã¯ã·ã§ã³ã«ãããäžèŠã«ãªã£ãã¡ã¢ãªãèªåçã«è§£æŸããŸãããããããã®ã¬ããŒãžã³ã¬ã¯ã·ã§ã³ã®åäœã«ãããããã©ãŒãã³ã¹ãäœäžããããšããããŸããé©åãªèšå®ããã¬ããŒãžã³ã¬ã¯ã·ã§ã³ã®åäœãç解ããããšã§ãããã©ãŒãã³ã¹ãåäžãããããšãã§ããŸãã
6. Javaç¬åŠã§ã®ææŠ: ããããšã³ãžãã¢ã«ãªãããã®ç§èš£
Javaã®ç¬åŠã¯ãå€ãã®ææŠã䌎ããŸããããããä¹ãè¶ããããšã§ããããšã³ãžãã¢ãžã®éãéãããŸãããã®ã»ã¯ã·ã§ã³ã§ã¯ãå®è·µçãªãããžã§ã¯ãã®åãçµã¿æ¹ããã³ãã¥ããã£ãšã®é¢ããæ¹ããããŠç¶ç¶çãªåŠã³ã®éèŠæ§ã«ã€ããŠè§£èª¬ããŸãã
6.1 å®è·µçãªãããžã§ã¯ãã®åãçµã¿æ¹
çè«ã ãã§ãªããå®éã®ãããžã§ã¯ããæãããããšã¯ãã¹ãã«ã磚ãäžã§éåžžã«éèŠã§ãããŸãã¯ãå°èŠæš¡ãªãããžã§ã¯ãããå§ããåŸã ã«ã¹ã±ãŒã«ã倧ããããŠããããšãããããããŸããäŸãã°ãç°¡åãªãŠã§ãã¢ããªã±ãŒã·ã§ã³ãããŒã«ãéçºãããããå ¬éããããšã§ãã£ãŒãããã¯ãåãåãããšãã§ããŸãã
6.2 ã³ãã¥ããã£ãšã®é¢ããæ¹
ããã°ã©ãã³ã°ã®åŠã³ã¯ãäžäººã§è¡ããã®ã§ã¯ãããŸãããå€ãã®ãšã³ãžãã¢ãéãŸãã³ãã¥ããã£ã«åå ããããšã§ãæ°ããç¥èãæè¡ãåŠã¶ããšãã§ããŸãããŸããä»ã®ãšã³ãžãã¢ãšã®äº€æµãéããŠãæ°ããèŠç¹ãã¢ã€ãã£ã¢ãåŸãããšãã§ããŸãã
6.3 ç¶ç¶çãªåŠã³ã®éèŠæ§
æè¡ã®äžçã¯æ¥ã é²åããŠããŸãããã®ãããäžåºŠåŠãã ã ãã§æºè¶³ãããç¶ç¶çã«æ°ããç¥èãæè¡ãåŠã¶ããšãéèŠã§ããç¹ã«Javaã¯ãæ°ããããŒãžã§ã³ãå®æçã«ãªãªãŒã¹ãããæ°ããæ©èœãæ¹åãè¡ãããŠããŸãã
æ°ããæè¡ããã¬ã³ããè¿œããããã ãã§ãªããåºæ¬çãªç¥èãå®æçã«èŠçŽãããšã倧åã§ããæ·±ãç解ãæã€ããšã§ãããé«åºŠãªæè¡ãåé¡è§£æ±ºã®ã¹ãã«ã身ã«ã€ããããšãã§ããŸãã
7. ãŸãšã
ãã®èšäºãéããŠãJavaã®ç¬åŠã«é¢ããå€å²ã«ãããæ å ±ãæäŸããŸãããæåŸã«ããã®é åãšææŠããããŠä»åŸã®åŠã³ã®æ¹åæ§ã«ã€ããŠãŸãšããŸãã
7.1 Javaç¬åŠã®é åãšææŠ
Javaã¯ãå¹ åºãã¢ããªã±ãŒã·ã§ã³é åã§äœ¿çšãããããã°ã©ãã³ã°èšèªã§ããããã®åŠã³ã¯éåžžã«äŸ¡å€ããããŸããç¬åŠãéããŠãèªåã®ããŒã¹ã§æ·±ãåŠã¶ããšãã§ããã®ãé åã®äžã€ã§ãããããããã®éã®ãã¯æ±ºããŠå¹³åŠã§ã¯ãããŸãããæ°ããæŠå¿µãæè¡ã®åãçµã¿ããããŠç¶ç¶çãªåŠã³ãæ±ããããŸãã
7.2 ä»åŸã®åŠã³ã®æ¹åæ§
Javaã®ç¬åŠãé²ããäžã§ãæ°ããæè¡ããã¬ã³ãã«ãç®ãåããããšãéèŠã§ããäŸãã°ãã¯ã©ãŠãæè¡ãAIãIoTãªã©ã®åéã§ã®Javaã®æŽ»çšæ¹æ³ãåŠã¶ããšã§ãããå¹ åºãç¥èã身ã«ã€ããããšãã§ããŸãã