public class AdvancedForExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] scores = {95, 71, 84, 93, 87};
int sum = 0;
for(int score : scores) {
sum = sum + score;
}
System.out.println("점수 총합 = " + sum);
double avg = (double)sum / scores.length;
System.out.println("점수 평균 = " + avg);
}
}
public class ArrayCopyByForExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] oldIntArray = {1, 2, 3};
int[] newIntArray = new int[5];
for(int i = 0; i < oldIntArray.length; i++) {
newIntArray[i] = oldIntArray[i];
}
for(int i = 0; i < newIntArray.length; i++) {
System.out.print(newIntArray[i] + ", "); // 1, 2, 3, 0, 0, : int 배열의 초기값은 0
}
}
}
public class ArrayCopyExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
String[] oldStrArray = {"java", "array", "copy"};
String[] newStrArray = new String[5];
System.arraycopy(oldStrArray, 0, newStrArray, 0, oldStrArray.length);
for(int i = 0; i < newStrArray.length; i++) {
System.out.print(newStrArray[i] + ", "); // java, array, copy, null, null,
}
}
}
public class ArrayCreateByNewExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] arr1 = new int[3];
for(int i = 0; i < 3; i++) {
System.out.println("arr1[" + i + "] : " + arr1[i]);
}
arr1[0] = 10;
arr1[1] = 20;
arr1[2] = 30;
for(int i = 0; i < 3; i++) {
System.out.println("arr1[" + i + "] : " + arr1[i]);
}
double[] arr2 = new double[3];
for(int i = 0; i < 3; i++) {
System.out.println("arr2[" + i + "] : " + arr2[i]);
}
arr2[0] = 0.1;
arr2[1] = 0.2;
arr2[2] = 0.3;
for(int i = 0; i < 3; i++) {
System.out.println("arr2[" + i + "] : " + arr2[i]);
}
String[] arr3 = new String[3];
for(int i = 0; i < 3; i++) {
System.out.println("arr3[" + i + "] : " + arr3[i]);
}
arr3[0] = "1월";
arr3[1] = "2월";
arr3[2] = "3월";
for(int i = 0; i < 3; i++) {
System.out.println("arr3[" + i + "] : " + arr3[i]);
}
}
}
public class ArrayCreateByValueListExample1 {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] scores = {83, 90, 87};
System.out.println("score[0] : " + scores[0]); // 83
System.out.println("score[1] : " + scores[1]); // 90
System.out.println("score[2] : " + scores[2]); // 87
int sum = 0;
for(int i = 0; i < 3; i++) {
sum += scores[i];
}
System.out.println("총합 : " + sum); // 총합 : 260
double avg = (double)sum /3;
System.out.println("평균 : " + avg); // 평균 : 86.6666666666667
}
}
public class ArrayCreateByValueListExample2 {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] scores;
scores = new int[] {83, 90, 87};
int sum1 = 0;
for(int i = 0; i < 3; i++) {
sum1 += scores[i];
}
System.out.println("총합 : " + sum1);
int sum2 = add(new int[] {83, 90, 87});
System.out.println("총합 : " + sum2);
System.out.println();
}
public static int add(int[] scores) {
int sum = 0;
for(int i = 0; i < 3; i++) {
sum += scores[i];
}
return sum;
}
}
public class ArrayInArrayExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[][] mathScores = new int[2][3];
for(int i = 0; i < mathScores.length; i++) {
for(int k = 0; k < mathScores.length; k++) {
System.out.println("mathScores[" + i + "][" + k + "] = " + mathScores[i][k]);
}
}
System.out.println();
int[][] englishScores = new int[2][];
englishScores[0] = new int[2];
englishScores[1] = new int[3];
for(int i = 0; i < englishScores.length; i++) {
for(int k = 0; k < englishScores.length; k++) {
System.out.println("englishScores[" + i + "][" + k + "] = " + englishScores[i][k]);
}
}
System.out.println();
int[][] javaScores = {{95, 80}, {92, 96, 80}};
for(int i = 0; i < javaScores.length; i++) {
for(int k = 0; k < javaScores.length; k++) {
System.out.println("javaScores[" + i + "][" + k + "] = " + javaScores[i][k]);
}
}
}
}
public class ArrayLengthExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] scores = {83, 90, 87};
int sum = 0;
for(int i = 0; i < scores.length; i++) {
sum += scores[i];
}
System.out.println("총합 : " + sum);
double avg = (double)sum / scores.length;
System.out.println("평균 : " + avg);
}
}
public class ArrayReferenceObjectExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
String[] strArray = new String[3];
strArray[0] = "Java";
strArray[1] = "Java";
strArray[2] = new String("Java");
System.out.println(strArray[0] == strArray[1]); // true : 동일한 String 객체를 참조하기 때문
System.out.println(strArray[0] == strArray[2]); // false : new 연산자로 객체 생성하면 새로운 String 객체 생성되기 때문
System.out.println(strArray[0].equals(strArray[2])); // true : 문자열을 비교하기 때문
}
}
public class StringEqualsExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
String strVar1 = "이현경";
String strVar2 = "이현경";
if(strVar1 == strVar2) {
System.out.println("strVar1과 strVar2는 참조가 같음");
} else {
System.out.println("strVar1과 strVar2는 참조가 다름");
}
if(strVar1.equals(strVar2)) {
System.out.println("strVar1과 strVar2는 문자열이 같음");
}
String strVar3 = new String("이현경");
String strVar4 = new String("이현경");
if(strVar3 == strVar4) {
System.out.println("strVar3과 strVar4는 참조가 같음");
} else {
System.out.println("strVar3과 strVar4는 참조가 다름");
}
if(strVar3.equals(strVar4)) {
System.out.println("strVar3과 strVar4는 문자열이 같음");
}
}
}