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iT-16-[Javaå匷ð¥ãã®ããã]
埩ç¿ð¥
ã»é å
ããŒã¿å[] é
ååã= new ããŒã¿å[èŠçŽ æ°]
int[] score = new int[3];
score[0] = 80;
// scoreã®ïŒçªç®ã«ã80ã代å
¥ããŠãã ããããæ·»åã¯ã0ããã¹ã¿ãŒãããããšã«æ³šæ
ããŒã¿å[] é
ååã= { å€1, å€2, ã»ã»ã»ã»}
é
å.length ã§ãé
åã®èŠçŽ æ°ãGet
class Array {
public static void main(String args[]) {
int[] score = new int[3]
score[0] = 80;
score[1] = 100;
score[2] = 70;
String[] name = {"é«æš", "西山", "å°æ¢
"};
System.out.println(name[0] + "ãã:" + score[0] + "ç¹");
System.out.println(name[1] + "ãã:" + score[1] + "ç¹");
System.out.println(name[2] + "ãã:" + score[2] + "ç¹");
System.out.println("åéšè
æ°:" + score.length + "人ã§ãã");
// score.lengthãããããšã§ããã®èŠçŽ ã®æ°ïŒèŠçŽ æ°ïŒãå©çšããããšãã§ããïŒïŒãããã
}
}
å€æ¬¡å é å
class MultiArray{
public static void main(String[] args){
int[][] allScore = new int[2][3];
allScore[0][0] = 80;
allScore[0][1] = 100;
allScore[0][2] = 75;
allScore[1][0] = 85;
allScore[1][1] = 95;
allScore[1][2] = 80;
// å€æ¬¡å
é
åã®åæå
// int[][] allScore = { {10, 20, 30}, {40, 50, 60} };
System.out.println(allScore[0][0] + "ç¹");
System.out.println(allScore[0][1] + "ç¹");
System.out.println(allScore[0][2] + "ç¹");
System.out.println(allScore[1][0] + "ç¹");
System.out.println(allScore[1][1] + "ç¹");
System.out.println(allScore[1][2] + "ç¹");
System.out.println("allScore.lengthïŒ" + allScore.length);
System.out.println("allScore[0].lengthïŒ" + allScore[0].length);
}
}
ã»æŒç®å
//å²ãç®
7 / 2 â 3
//ããŸãã®æ°
7 % 2 â 1
//a = a + bãšåãã
a += bã
//aã«bãå ããŠãaã«å床代å
¥ããã
//a = a + 1;ãšåãã
a ++;
a --;
class Operator {
public static void main(String[] args){
//ã³ãã³ãã©ã€ã³ããå
¥åããæåååããint aãšããŠå®£èšãã
int a = Integer.parseInt(args[0]);
int b = Integer.parseInt(args[1]);
System.out.println("a =" + a + "b =" + b );
System.out.println("a + b =" + (a + b));
System.out.println("a - b =" + (a - b));
System.out.println("a / b =" + (a / b));
System.out.println("a % b =" + (a % b));
System.out.println("a >= 0 :" + (a >= 0);
System.out.println("(a >= 0) && (b >= 0):" + ((a >= 0)&&(b >= 0));
}
}
é¢ä¿æŒç®å
trueãfalse
è«çæŒç®å
ïŒa >= 0ïŒ&& ïŒb >= 0ïŒ
â&&ã¯ããã€ããè¡šãã
â||ã¯ããããã¯ããè¡šãã
ã»åºæ¬ããŒã¿ã®åå€æ
è¡šçŸã®å¹
ãåºãé ãçãïŒèªåã§ïŒ
double, float, long, int, short, byte
倧ããç®±ãå°ããªç®±ã«ããããå
¥ããïŒä»£å
¥ããïŒããã«ã¯ã
ãã£ã¹ããšãããã®ãå¿
èŠãããããããæã«ãªã£ãããããæžãã
class FukuKau {
public static void main(String[] args){
//æã®ãã ããå
¥åããããããargs[0]ãåŒæ°ãšãªãpriceã«ä»£å
¥ããŠãããã
int price = Integer.parseInt(args[0]);
ãããããããã
ãããããããã//ïŒ.ïŒïŒã¯ãæµ®åå°æ°ç¹æ°ãšããŠdoubleã§å®£èšãããå€ã代å
¥ããŠããã
double rate = 0.08;
ãããããããã//amountãšããæŽæ°åã宣èšããŠããã
int amount;
ãããããããã/*amountã«ãçšèŸŒéé¡ã®åŒã代å
¥ããããã®ãšããdoubleåã64bit,intåã32bitãªã®ã§ãå°ããª
ããããããããããããç®±ã«ã倧ããªç®±ãããããå
¥ããããšã«ãªãããã®ããããŠãïŒãã£ã¹ãã䜿ãå¿
èŠãããã
ãããããããããããããã£ãŠãïŒintïŒã§å€æåŸã®ããŒã¿åãå
¥ãamountã«ä»£å
¥ããŠããããã*/
ãããããããããããã
amount = (int)(price * (1 + rate))
System.out.println("çšèŸŒéé¡ã¯ã" + amount + "åã§ãã");
}
}
ã»æ§é åããã°ã©ãã³ã°
以äžãçµã¿åãããŠããã°ã©ã ãããããšãæèããŠæžããšãããã°ã©ã ããããããããªãã
â é 次é²è¡
â|åŠç|â|åŠç|â|åŠç|â|åŠç|â|åŠç|â|åŠç|â|åŠç|â|åŠç|â|åŠç|âã»ã»
â¡åå²
â|æ¡ä»¶|âtrueâ|åŠç|â
ããâ â
ãã |â falseâ|åŠç|â |
â¢ç¹°ãè¿ã
â|æ¡ä»¶|â|åŠç|â|æŽæ°ïŒ|â|æ¡ä»¶|â|åŠç|â|æŽæ°ïŒ|â
Ifæ
if (æ¡ä»¶åŒ) {
åŠçïŒ
} else {
ããåŠçïŒ
ãããã}
ã»else ifæ
if(price >= 3000){
discount = 300;
} else {
discount = 0;
}
ã®æ¡åŒµïŒïŒããã«æ¡ä»¶åŒãå ¥ããå Žåã¯ãã¡ãã
if(æ¡ä»¶åŒ1){
åŠçïŒ;
} else if (æ¡ä»¶åŒ2)
åŠçïŒ;
} else {
åŠç3;
}
ã»swichæ
swich(åŒ){
case1:
åŠç1
break1;
case2:
åŠç2
break2;
case3:
åŠç3
break3;
}
ã»åŒã«å
¥ãã®ã¯ãbyte, short, int, charåã§ããã
ã»åŒã®å€ã«ãã£ãŠãåŠçã®éå§äœçœ®ã決ãŸãïŒïŒ
ã»breakã¯äœããšãããšããã{ã}ãæããŸãïŒãšããæå³ã
ã»whileæ
while(æ¡ä»¶åŒ){
åŠç
case1:
åŠç1
break1;
case2:
åŠç2
break2;
case3:
åŠç3
break3;
}
ååã®åé¡åŸ©ç¿ð¥ð¥
ã»ïŒå
é¢ç©ãšé«ãã»å¹ ã»é¢ç©ã®è¡šç€ºãããªããã
class Triangle{
public static void main(String[] args){
int height = Integer.parseInt(args[0]);
int width = Integer.parseInt(args[1]);
int area;
//é¢ç©ã®èšç®
//é«ãã»å¹
ã»é¢ç©ã®è¡šç€º
}
}
åçã³ãŒã
class Triangle{
public static void main(String[] args){
int height = Integer.parseInt(args[0]);
int width = Integer.parseInt(args[1]);
int area;
//é¢ç©ã®èšç®
area = height * width / 2;
//é«ãã»å¹
ã»é¢ç©ã®è¡šç€º
System.out.println("é«ãïŒ" + height);
System.out.println("å¹
ãïŒ" + width);
System.out.println("é¢ç©ïŒ" + area);
}
}
ã»ïŒå
é¢ç©ãå°æ°ç¹ç¬¬ïŒäœãŸã§è¡šç€ºããããã«ããŠãã ããã
class Sample003{
public static void main(String[] args){
int radius = 15;
double pi = 3.141592;
double area;
double minus;
area = radius * radius * pi;
//å°æ°ç¹ç¬¬ïŒäœä»¥éãåãæšãŠ
System.out.println("ååŸïŒ" + radius);
System.out.println("é¢ç©ïŒ" + area);
}
}
åçã³ãŒã
class Circle{
public static void main(String[] args){
int radius = Integer.parseInt(args[0]);
double pi = 3.141592;
double area;
area = radius * radius * pi;
//å°æ°ç¹ç¬¬ïŒäœä»¥éãåãæšãŠ
area = (int)(area * 100);
area = area / 100;
System.out.println("ååŸïŒ" + radius);
System.out.println("é¢ç©ïŒ" + area);
}
}
ã»ïŒå
äºã€ã®æ°åãå ¥ããæã«ã倧ããæ¹ã®å€ã衚瀺ãããªããã
class Comparison{
public static void main(String[] args){
int a = Integer.parseInt(args[0]);
int b = Integer.parseInt(args[1]);
//倧ããã»ãã®å€ã衚瀺
}
}
åèã³ãŒã
class Comparison{
public static void main(String[] args){
int a = Integer.parseInt(args[0]);
int b = Integer.parseInt(args[1]);
//倧ããæ¹ã®å€ã衚瀺
if( a > b ){
System.out.println("倧ããã®ã¯" + a + "ã§ã");
} else if( b > a ){
System.out.println("倧ããã®ã¯" + b + "ã§ã");
} else {
System.out.println("åãã§ã");
}
}
}
ã»ïŒå
ã¡ãã»ãŒãžãïŒïŒå衚瀺ãããããã°ã©ã ãäœããªããã
class LoopMessage{
public static void main(String[] args){
//ã¡ãã»ãŒãžã10å衚瀺ïŒwhileæïŒ
}
}
class LoopMessage{
public static void main(String[] args){
int i = 1;
//ã¡ãã»ãŒãžã10å衚瀺ïŒwhileæïŒ
while(i <= 10){
System.out.println(i +"åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ");
i ++;
}
}
}
ã¡ãªã¿ã«ãChat-gptïŒåæã«ãžãããããšèªãã§ãããïŒã«èããã®ã§ããã以äžã®å 容ã§ãã
ã³ãŒãã®ç®çã¯ãæå®ãããã¡ãã»ãŒãžã10å衚瀺ããããšã§ãã`i`ãšããå€æ°ãåæå€1ã§å®£èšããã`while`ã«ãŒãã䜿ãããŠããŸããã«ãŒãã®æ¡ä»¶ã¯ã`i`ã10æªæºã§ããããšã§ããã«ãŒãå éšã§ã¯ã`System.out.println`ã¡ãœããã䜿çšããŠã`i`ã®å€ãšæå®ãããã¡ãã»ãŒãžãåºåãã`i`ãã€ã³ã¯ãªã¡ã³ãããŠããŸãã
ãããã£ãŠãããã°ã©ã ãå®è¡ãããšã以äžã®ãããªçµæã衚瀺ãããŸãã
1åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
2åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
3åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
4åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
5åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
6åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
7åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
8åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
9åç®ïŒããªãŒã©ãŒãã³ã°ãåºããããïŒ
10åç®ã¯æ¡ä»¶ã`i < 10`ã§ããããã衚瀺ãããŸããã
ãšã®ããšã§ããã
ã»ïŒå
ã³ãã³ãã©ã€ã³ããå ¥åããæååãããã®ãŸãŸè¡šç€ºã§ããããã°ã©ã ãforæã䜿ã£ãŠè¡šç€ºããªããã
class Echo{
public static void main(String[] args){
//ã³ãã³ãã©ã€ã³ã®å
¥åæååã衚瀺ïŒforæïŒ
}
}
>Java Echo aa bb cc
ãšå ¥ãããããã®ãŸãŸ aa bb ccãšãããã®ãåºãŠããã¯ãã
åèã³ãŒã
class Echo{
public static void main(String[] args){
//ã³ãã³ãã©ã€ã³ã®å
¥åæååã衚瀺ïŒforæïŒ
for(int i = 0; i < args.length; i++) {
System.out.println(args[i]);
}
}
}
ã§ã¯ãç¶ãã
å匷ð¥ð¥ð¥
ã»ãªããžã§ã¯ãæåãšã¯
class NonObject{
public static void main(String[] args){
//ããŒã¿ã®ä»£å
¥
int[] score = {80, 100, 75};
String[] name = {"è
å", "æå±±", "寺島"};
//ããŒã¿ã®è¡šç€º
for(int i = 0; i < score.length; i++) {
System.out.println(name[i] + "ããïŒ" + score[i] + "ç¹");
}
}
}
ãšããã³ãŒãã
ïŒåäœã£ãã³ãŒãã¯ãæŽæ°ïŒå€æŽïŒããããšãã»ãšãã©ã§ããã
äŸãã°ããã®èŠçŽ æ°ã®äžã§ãçåŸãäžäººå¢ãããšããã
ãããã¯ãæç§ã®æ°ãå¢ãããããšèããã
class NonObject{
public static void main(String[] args){
//ããŒã¿ã®ä»£å
¥
int[] score1 = {80, 100, 75, 90};
int[] score2 = {90, 80, 85, 70};
String[] name = {"è
å", "æå±±", "寺島"};
String[] name = {"æ°åŠ", "è±èª"};
//ããŒã¿ã®è¡šç€º
for(int i = 0; i < score.length; i++) {
System.out.println(name[i] + "ããïŒ" + score[i] + "ç¹");
}
}
}
ãã¡ãã¡é¢åã ããŸãã誰ã®ãäœã®åŸç¹ãäœç¹ããããããªãã»ã»ã»ã
人ããšã®ç¹æ°ãããå°ããŸãšããŠã管çããããã§ããªãããèããå¿ èŠããããšèããã
Javaã«ã¯ãå®è¡çšã®ã¯ã©ã¹ãšãèšèšå³ã¯ã©ã¹ã®äºã€ãããã
ã¯ã©ã¹ïŒèšèšå³ïŒ
ã»å±æ§âäœã®ããŒã¿ãæã£ãŠããã®ãã
ïŒååãæç§ãç¹æ°ãªã©ïŒ
ã»æäœâäœã®åŠçãã§ãããã
ïŒç¹æ°ã衚瀺ããïŒ
âããã«ãã£ãŠãååïŒè
åïŒè±èªïŒ90ïŒåœèªïŒ80ïŒ
ååïŒäœè€ïŒè±èªïŒ50ïŒåœèªïŒ60ïŒãªã©ãšããã®ããã®ãŸãŸäœ¿ããã
ãã®ãããªãã¯ã©ã¹ããäœãããå®äœïŒã¢ãïŒããobjectïŒãªããžã§ã¯ãïŒãšåŒã¶ã
ãã®ãªããžã§ã¯ããäžå¿ã«ããã°ã©ã ãäœã£ãŠããããšãããªããžã§ã¯ãæåãšããã
ã»ã¡ãªãã
éçºå¹çãä¿å®æ§ãã¡ã¢ãªå¹çãã·ã¹ãã åãªã©ïŒïŒ
ã¯ã©ã¹ïŒèšèšå³ïŒ
ã»å±æ§âäœã®ããŒã¿ãæã£ãŠããã®ããâ ãããã°ã©ã ã®äžçã§ã¯ãå€æ°
ïŒååãæç§ãç¹æ°ãªã©ïŒ
ã»æäœâäœã®åŠçãã§ããããâ ãããã°ã©ã ã®äžçã§ã¯ãã¡ãœãã
ïŒç¹æ°ã衚瀺ããïŒ
ãããã®èšãæ¹ããã£ã¡ãã«ãªããªãããã«ããã
ã»å€æ°ã®å®çŸ©
ããŒã¿åãå€æ°åïŒ
äŸ
class Student{
//ã¡ã³ãå€æ°ïŒå±æ§ïŒ
String name;
int engScore;
int mathScore;
以äžã¯ãã®äžã«ç¶ã
ã»ã¡ãœããã®å®çŸ©
æ»ãå€ã®åãã¡ãœããåïŒåŒæ°ãªã¹ãïŒ{
ïŒåŠçïŒ
}
ã¡ãœããã¯ãåŒã³åºãåŽãšãåŒã³åºãããåŽãããã
//ã¡ãœããïŒæäœïŒ
void display(){
System.out.println(name + "ãã");
System.out.println("è±èª" + engScore + "ç¹ã»æ°åŠ" + mathScore + "ç¹");
}
void setScore(int eng, int math){
engScore = eng;
mathScore = math;
}
double getAvg(){
double avg = (engScore + mathScore) / 2.0;
return avg;
}
}
ã»åŒæ°ã»ã»åŒã³åºãå
ããåãåãå€ã®ããšã
ã»æ»ãå€ã»ã»ã¡ãœããã®åŠçã®åŸã«ãåŒã³åºãããšã«è¿ãå€ãreturnã§æå®ããããšãã§ããã
ãŸããäœãè¿ããªãå Žåã¯ãvoidãèšè¿°ããã
void display(){
System.out.println(name + "ãã");
System.out.println("è±èª" + engScore + "ç¹ã»æ°åŠ" + mathScore + "ç¹");
}
âã¯ãåŒæ°ããªãããïŒïŒã¯æžããŠããããšã«æ³šæããŠããã
//ããŒã¿åãå€æ°å
void setScore(int eng, int math){
engScore = eng;
mathScore = math;
}
âã¯ãåŒæ°ããããæ»ãå€ããªãã
double getAvg(){
double avg = (engScore + mathScore) / 2.0;
return avg;
}
}
âã¯ãåŒæ°ãªããæ»ãå€ããã®ãã¿ãŒã³ããã
ãŸããåŒæ°ã®äžã§å®çŸ©ããæå¹ç¯å²ã¯ããã®ãããã¯ã®äžã§ãã䜿ããªãã®ã§ã泚æãããå¿ èŠãããã
ã»ãªããžã§ã¯ãã®äœ¿ãæ¹
â ãªããžã§ã¯ããçæããããš
â¡å€æ°ã»ã¡ãœãããå©çšããããš
â ãªããžã§ã¯ããçæããããš
ã¯ã©ã¹åããªããžã§ã¯ãåã= newãã¯ã©ã¹åïŒïŒ;
Student stul = new Student( );
new ããŒã䜿ããšãã¡ã¢ãªäžã«æ°ããé åã確ä¿ããããé åã§ãåºãŸããã
ããã©ã«ãåæå€ãå ¥ãããã®ããã«ãããã°ã©ã ã«ãããŠããªããžã§ã¯ããäœãããšããã€ã³ã¹ã¿ã³ã¹åãšããã
â¡å€æ°ã»ã¡ãœãããå©çšããããš
ãªããžã§ã¯ãå.å€æ°å
ãªããžã§ã¯ãå.ã¡ãœããåïŒåŒæ°ïŒ
stul.name = "è
å";
stul.setScore(80,90);
äŸ
èšèšå³
class Student{
//ã¡ã³ãå€æ°ïŒå±æ§ïŒ
String name;
int engScore;
int mathScore;
ãã //ã¡ãœããïŒæäœïŒ
void display(){
System.out.println(name + "ãã");
System.out.println("è±èª" + engScore + "ç¹ã»æ°åŠ" + mathScore + "ç¹");
}
void setScore(int eng, int math){
engScore = eng;
mathScore = math;
}
double getAvg(){
double avg = (engScore + mathScore) / 2.0;
return avg;
}
}
èšèšå³ãããšã«ãStuSampleã¯ã©ã¹ãåãããŠããã
class StuSample{
public static void main(String[] args){
Student stu1 = new Student();
stu1.name = "è
å";
stu1.setScore(90, 80);
stu1.display();
System.out.println("å¹³å" + stu1.getAvg() + "ç¹");
}
}
ã¡ãã£ãšè§£èª¬ãããŠããã
Student stu1 = new Student();
ããã¯ããŸãã«ãªããžã§ã¯ãçæãããŠãããstu1ãšãããªããžã§ã¯ãåã§ãStudentã¯ã©ã¹ã䜿ã£ãŠãããšèšãããïŒèšãæ¹ã¯éãªã®ããªãïŒ
ç§ã®èããšããŠã¯ãèšèšå³ã®äžã®Studentã¯ã©ã¹ã®äžã®ãstu1ãªããžã§ã¯ããäœããšèããŠããããããããããšã«ãã£ãŠãã€ã³ã¹ã¿ã³ã¹ãçæããããšãã§ããã
ãªããžã§ã¯ãã®çæãå
ã§ãããã§ãªããšå€æ°ãã¡ãœããã¯å©çšã§ããªãã
åºæ¬äžããäžã«ã³ãŒãã¯ããŸããã®ã§ããã¡ããåãStuSampleã¯ã©ã¹ã®äžã§ãçæã¯æåã®æ¹ã«æžãå¿
èŠãããã
ãã®åŸã
stu1.name = "è
å";
stu1.setScore(90, 80);
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stul.name = "è
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stul.setScore(80,90);ã䜿ã£ãŠããã
stu1.name = "è
å";
âã¯String nameã§å®£èšããã¡ã³ãå€æ°ãïŒå±æ§ïŒ
stu1.setScore(90, 80);
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void setScore(int eng, int math){
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stu1.display();
System.out.println("å¹³å" + stu1.getAvg() + "ç¹");
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stu1.display()ã¯ã
void display()
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void display(){
System.out.println(name + "ãã");
System.out.println("è±èª" + engScore + "ç¹ã»æ°åŠ" + mathScore + "ç¹");
}
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