ArrayException
public class ArrayException{
public static void main(String[] args){
int[] intArray = new int[5];
intArray[0] = 0;
try {
for(int i=0; i<5; i++) {
intArray[i+1] = i+1 + intArray[i];
System.out.println("intArray[" + i + "]" + "=" + intArray[i]);
}
}
catch (ArrayIndexOutOfBoundsException e) {
System.out.println("배열의 인덱스 범위를 벗어났습니다.");
}
}
}
Arraylength
import java.util.Scanner;
public class Arraylength{
public static void main(String[] args){
int intArray[] = new int[5];
int sum = 0;
Scanner scanner = new Scanner(System.in);
System.out.print("Enter " + intArray.length + " integers >> ");
for(int i=0; i<intArray.length; i++)
intArray[i] = scanner.nextInt();
for(int i=0; i<intArray.length; i++)
sum += intArray[i];
System.out.println("Average: " + (double)sum/intArray.length);
scanner.close();
}
}
Barchart
public class BarChart{
public static void main(String[] args){
int[] data = {5,2,18,9,6,11,4,5,13,7};
for(int n:data) {
System.out.printf("%2d ", n);
for(int i=0; i<n; i++)
System.out.print("*");
System.out.println();
}
}
}
Calc
public class Calc{
public static void main(String[] args){
double sum=0;
for(int i=0; i<args.length; i++)
sum += Double.parseDouble(args[i]);
System.out.println("sum = " + sum);
}
}
DivideByZero
import java.util.Scanner;
public class DivideByZero{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int dividend;
int divisor;
while(true) {
System.out.print("나뉨수를 입력하시오: ");
dividend = input.nextInt();
System.out.print("나뉫수를 입력하시오: ");
divisor = input.nextInt();
try {
System.out.println(dividend + "를 " + divisor + "로 나누면 몫은 " + dividend/divisor + "입니다.");
break;
}
catch(ArithmeticException e) {
System.out.println("0으로 나눌 수 없습니다! 다시 입력하세요: ");
}
input.close();
}
}
}
Foreach
public class Foreach{
enum week {MONDAY, TUESDAY, WENDSDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY}
public static void main(String[] args){
int[] num = {1,2,3,4,5};
int sum=0;
for(int k:num)
sum+=k;
System.out.println("Sum " + sum);
String names[] = {"apple", "pear", "banana", "cherry", "strawberry", "grapes"};
for(String s:names)
System.out.print(s + " ");
System.out.println();
for(week day:week.values())
System.out.print(day + " ");
System.out.println();
}
}
InputException
import java.util.Scanner;
import java.util.InputMismatchException;
public class InputException{
public static void main(String[] args){
Scanner scanner = new Scanner(System.in);
System.out.println("정수 3개를 입력하시오");
int sum = 0, n = 0;
for(int i=0; i<3; i++) {
System.out.print("[" + i + "] " + ">>");
try {
n = scanner.nextInt();
}
catch(InputMismatchException e) {
System.out.println("정수가 아닙니다. 다시 입력하시오.");
scanner.nextInt(); // 정수를 버리지 않고 토큰을 버린다.
i--; // 인덱스가 증가하지 않도록 미리 감
continue;
}
sum += n;
}
System.out.println("합은 " + sum);
scanner.close();
}
}
InstanceOfEx
class Person{}
class Student extends Person{}
class Researcher extends Person{}
class Professor extends Researcher{}
public class InstanceOfEx{
static void print(Person p){
if(p instanceof Person) System.out.print("Person ");
if(p instanceof Student) System.out.print("Student ");
if(p instanceof Researcher) System.out.print("Researcher ");
if(p instanceof Professor) System.out.print("Professor ");
System.out.println();
}
public static void main(String[] args){
System.out.print("new Student() ->\t"); print(new Student());
System.out.print("new Researcher() ->\t"); print(new Researcher());
System.out.print("new Professor() ->\t"); print(new Professor());
}
}
IrregularArray
public class irregularArray{
public static void main(String[] args){
int intArray[][] = new int[4][];
intArray[0] = new int[3];
intArray[1] = new int[2];
intArray[2] = new int[3];
intArray[3] = new int[2];
for(int i=0; i<intArray.length; i++)
for(int j=0; j<intArray[i].length; j++)
intArray[i][j] = (i+1) * 10 + j;
for(int i=0; i<intArray.length; i++) {
for(int j=0; j<intArray[i].length; j++)
System.out.print(intArray[i][j] + " ");
System.out.println();
}
}
}
MethodOverridingEx
class Shape{
public Shape next;
public Shape(){next = null;}
public void draw(){
System.out.println("Shape");
}
}
class Line extends Shape{
public void draw(){
System.out.println("Line");
}
}
class Rect extends Shape{
public void draw(){
System.out.println("Rect");
}
}
class Circle extends Shape{
public void draw(){
System.out.println("Circle");
}
}
public class MethodOverringEx{
static void paint(Shape p){
p.draw();
}
public static void main(String[] args){
Line line = new Line();
paint(line);
paint(new Shape());
paint(new Line());
paint(new Rect());
paint(new Circle());
}
}
NumException
public class NumException{
public static void main(String[] args){
String[] stringNumber = {"23", "12", "3.141592", "998"};
int i=0;
try {
for(i = 0; i<stringNumber.length; i++) {
int j = Integer.parseInt(stringNumber[i]);
System.out.println("숫자로 변환된 값은 " + j);
}
}
catch(NumberFormatException e) {
System.out.println(stringNumber[i] + "는 정수로 변환할 수 없습니다.");
}
}
}
ReturnArray
public class ReturnArray{
static int[] makeArray() {
int temp[] = new int[4];
for(int i=0; i<temp.length; i++)
temp[i] = i;
return temp;
}
public static void main(String[] args){
int intArray[];
intArray = makeArray();
for(int i=0; i<intArray.length; i++)
System.out.print(intArray[i]+" ");
}
}
ScoreAverage
public class ScoreAverage{
public static void main(String[] args){
double score[][] = {{3.3, 3.4}, {3.5, 3.6}, {3.7, 4.0}, {4.1, 4.2}};
double sum=0;
for(int year=0; year<score.length; year++)
for(int term=0; term<score[year].length; term++)
sum += score[year][term];
int n = score.length;
int m = score[0].length;
System.out.println("Average: " + sum/(n*m));
}
}
TestAverage
public class TestAverage{
public static void main(String[] args){
int score[][] = {{87, 96, 70},
{68, 87, 90},
{94, 100, 90},
{100, 81, 82},
{83, 65, 85},
{78, 87, 65},
{85, 75, 83},
{91, 94, 100},
{76, 72, 84},
{87, 93, 73}};
for(int student=0; student<score.length; student++) {
for(int test=0; test<score[student].length; test++)
System.out.printf("%4d ", score[student][test]);
System.out.printf("%.1f\n", getAverage(score[student]));
}
for(int test=0; test<score[0].length; test++)
System.out.printf("%4.1f ", getTestAverage(score, test));
System.out.println();
}
public static double getAverage(int[] arr){
double m=0.0;
for(int d:arr)
m+=d;
return m / arr.length;
}
public static double getTestAverage(int[][] arr, int test){
double m=0.0;
for(int student=0; student<arr.length; student++)
m+=arr[student][test];
return m / arr.length;
}
}
