JAVA 정리 2

 

Boolean can only be either true or false. Do not use double quotes.

&& = and, || = or

 

Control flow

class Main {
    public static void main(String[] args) {
        System.out.println("Hello Java");
 
        if(condition) {
            //Run this code;
        } else if (condition) {
            //Run this code;
        } else {
            //Run this code;
        }
    }
}

 

Switch statements.

class Main {
    public static void main(String[] args) {
        System.out.println("Hello Java");
 
        switch (value of contidion) {
            case value1 :
                //Run this code;
                break;
            case value2 :
                //Run this code;
                break;
            case value3 :
                //Run this code;
                break;
        }
    }
}

 

Default case

In switch statements, you can set a default case for when none of the cases match.

            default :
                //Run this code;
                break;
        }

 

While loops

class Main {
    public static void main(String[] args) {
        System.out.println("Hello Java");
 
        while (condition) {
            //Run this code;
        }
    }
}

 

for loops

class Main {
    public static void main(String[] args) {
        System.out.println("Hello Java");
 
        for (int i=1; i<=5 ; i++) {
            //Run this code;
        }
    }
}

 

Using continue : continue statements skip the loop

ex ))

class Main {
    public static void main(String[] args) {
        System.out.println("Hello Java");
 
        for (int i=1; i<=10 ; i++) {
            if ( i % 3 == 0) {
                continue; //skip the rest of the code in the loop
                          //if the number is divisible by 3
            }
            System.out.println(i);
        }
    }
}

 

Arrays [ ]

When declaring a variable for an array, you have to put [ ] after the type of each element.

ex ) int [ ] - array of integers, int [ ] numbers = { 5, 13, 29 };

String [ ] - array of strings

 

Array has a method called length, which counts the number of elements in an array.

ex ) String [ ] names = { "Jones", "Ken" };

System.out.println( names.length );   -> 2

 

Enhanced for loops

class Main {
    public static void main(String[] args) {
        System.out.println("Hello Java");
 
        for ( dataType variableName : arrayName ) {
            //Run this code;
        }
 
        ex)
        String [] names = {"John", "Ken"};
        for (String name : names) {
            System.out.println( name );
        }
    }
}

 

 

 

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