[With The Wiener] 여기는 미래의 IT융합인재가 공부하는 공간입니다.

<[java]>







[기본과정, 1단계]

자! 이제 시작합니다 ^^



1. 입력 & 출력 

<프로그램-1>

//컴파일 방법: javac test.java
//실행방법: java test

public class test{
    public static void main(String[] args){
        System.out.println("hi");
        int a=10;
        int b=10,c,i,sum=0;
        c=a+b;
        if(c>15){
            System.out.println("a + b=" + c);
        }
        for(i=0; i<=5; i++){
            sum+=i;
        }
        System.out.println("sum="+sum);
    }
}






2. 함수 

<프로그램-1>


//컴파일 방법: javac test1.java
//실행방법: java test1

class AA{
    int x;
    void add(int x){
        x=x+50;
    }
    void add(AA aa){
        aa.x=aa.x+40;
    }
    void addNew(AA aa){
        aa=new AA();
    }
    void add(int[] arr){
        arr[0]++;
    }
}
public class test1{

    public static void main(String[] args){
        AA aa=new AA();
        aa.x=100;
        int[] arr=new int[1];
        
        aa.add(aa.x);
        System.out.println("aa.x="+aa.x);
        
        aa.add(aa);
        System.out.println("aa.x="+aa.x);

        aa.add(aa);
        System.out.println("aa.x="+aa.x);
        
        aa.addNew(aa);
        System.out.println("aa.x="+aa.x);
        
        aa.add(arr);
        System.out.println("arr[0]="+arr[0]);

    }
} 





3. 상속

<프로그램-1>


class P{
    int p=10;
    void pm()
    {
        System.out.println("parent");
    }
}
class C extends P{
    int c=20;
    void cm()
    {
        System.out.println("child");
    }
}
public class test2{
    public static void main(String[] args){
        int sum=0;
        sum=Integer.parseInt(args[0])+Integer.parseInt(args[1]);
        System.out.println("sum="+sum);
        
        C c=new C();
        System.out.println("c.p="+c.p);
        System.out.println("c.c="+c.c);
        c.pm();
        c.cm();
    }
} 






4. args

<프로그램-1>


public class test03 {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String args1 = args[0];
        String args2 = args[1];
        
        System.out.println("args1 = " +  args1);
        System.out.println("args2 = " +  args2);
    }

} 





5. var

<프로그램-1>


public class test04{
    public static void main(String[] args) {
        boolean var_boolean = true;
        byte var_byte  = 127;
        short var_short = 32767;
        char var_char1 = 66;
        char var_char2 = 'A';
        char var_char3 = '\u0041';
        int var_int = 100000;
        
        long var_long = 1000000;
        float var_float = 3.14f;
        double var_double = 3.14;

        System.out.println("var_boolean = " + var_boolean);
        System.out.println("var_byte = " + var_byte);
        System.out.println("var_short = " + var_short);
        System.out.println("var_char1 = " + var_char1);
        System.out.println("var_char2 = " + var_char2);
        System.out.println("var_char3 = " + var_char3);
        System.out.println("var_int = " + var_int);
        System.out.println("var_long = " + var_long);
        System.out.println("var_float = " + var_float);
        System.out.println("var_double = " + var_double);
    }
} 






6. 따라해보세요

<프로그램-1>


public class OperationTest4 {
    public static void main(String[] args) {
        int x = 100;
        int y = 200;
        boolean result = false;
        
        result = x < y && y >= 200;
        System.out.println("x < y && y >= 200 = " + result);
        
        result = x < y && y < 200;
        System.out.println("x < y && y < 200 = " + result);
        result = x > y && y++ > 200;
        System.out.println("x > y && y++ > 200 = " + result);
        System.out.println("y = " + y);
        result = x < y || y >= 200;
        System.out.println("x < y || y >= 200 = " + result);
        result = x < y || y < 200;
        System.out.println("x < y || y < 200 = " + result);
        result = x > y || y++ > 200;
        System.out.println("x > y || y++ > 200 = " + result);
        System.out.println("y = " + y);
        result = x < y || y++ > 200;
        System.out.println("x < y || y++ > 200 = " + result);
        System.out.println("y = " + y);
        result = !(x > y);
        System.out.println("!(x > y) = " + result);        
    }
} 






7. 따라해보세요

<프로그램-1>


public static void main(String[] args) {
        int x = 10;
        int y = 5;
        boolean result = false;
        
        result = x > y;
        System.out.println("x > y = " + result);
        
        result = x < y;
        System.out.println("x < y = " + result);
    
        result = x >= y;
        System.out.println("x >= y = " + result);
        
        result = x <= y;
        System.out.println("x <= y = " + result);
        
        result = x == y;
        System.out.println("x == y = " + result);
        
        result = x != y;
        System.out.println("x <= y = " + result);
    }
} 





8. 따라해보세요

<프로그램-1>


public class test10{
    public static void main(String[] args) {

        int num = 3;
        int[] array1 = new int[3];
        
        for(int i=0;i<array1.length;i++){
            array1[i] = num++;
        }
        
        for(int i=0;i\<array1.length;i++){
            System.out.println("array1[" + i + "] = " + array1[i]);
        }
        
    }
} 







9. 배열

<프로그램-1>


public class ArrayTest3 {
    public static void main(String[] args) {
        String cities[] = {"seoul","sunchun","mokpo","yeasu","masan","daegu"}; 
        String nations[] = new String[]{"korea","japen","miguk","chia","bukhan"};
        
        for(int i=0;i<cities.length;i++){
            System.out.println("cities[" + i + "] = " + cities[i]);
        }
        for(int i=0;i<nations.length;i++){
            System.out.println("nations[" + i + "] = " + nations[i]);
        }
    }
}






10. Scanner

<프로그램-1>


import java.util.Scanner;
public class test12 {
    public static void main(String[] args) {
        String names[] = new String[]{"kim","hong","babo","hoho","ah","tp","aq"};
        Scanner sc = new Scanner(System.in);
        int index=-1;
        do{
            System.out.println("who are you?");
            System.out.println("hi!");
            String name = sc.next();
            for(int i=0;i<names.length;i++){
                if(name.equals(names[i])){
                    index = i;
                }
            }
            if(index != -1){
                System.out.println(name + "," + index + ".");
                break;
            }
            System.out.println("No.");
        }
        while(true);
    }
} 





11. 따라하기

<프로그램-1>


public class test13 {
    public static void main(String[] args) {
        String names[] = new String[]{"kim","hong","park"};
        
        for(String name : names){
            System.out.println(name);
        }
    }
} 






12. 따라하기

<프로그램-1>


class Sawon3{
    String name = "park";
    String displayInfoSuper(){
        String name = "hi";
        return name;
    }

}
class Sales3 extends Sawon3{    
    String name = "hong";
    String displayInfoLocal(){
        String name = "babo";
        return name;
    }
    String displayInfoThis(){
        String name = "hobak";
        return this.name;
    }
    String displayInfoSuper1(){
        String name = "hi";
        return super.name;
    }

}
public class test14{
    public static void main(String[] args) {
        Sales3 sales3 = new Sales3();
        System.out.println("local.name = " + sales3.displayInfoLocal());
        System.out.println("this.name = " + sales3.displayInfoThis());
        System.out.println("super.name = " + sales3.displayInfoSuper());
        System.out.println("superk.name = " + sales3.displayInfoSuper1());
    }
}






13. 따라하기

<프로그램-1>


public class VariableKind {
    int memVar;
    static int staticVar;
    public static void main(String[] args) {
        int localVar;
        
        VariableKind vk1 = new VariableKind();
        System.out.println("vk1.memVar = " + vk1.memVar);
        System.out.println("vk1.staticVar = " + vk1.staticVar);
        System.out.println("VariableKind.staticVar = " + VariableKind.staticVar);
        System.out.println("staticVar = " + staticVar);
        VariableKind vk2 = new VariableKind();
        vk1.staticVar = 20;
        System.out.println("vk2.staticVar = " + vk2.staticVar);
    }
}








여기까지 오셨군요!~ 

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감사합니다 ^^

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