[JAVA 다른 KOTLIN ] function 기초, 프로퍼티의 getter setter

0. 이전글

2018/12/13 - [Java와 다른 Kotlin] - [JAVA 다른 KOTLIN ] if-else, switch, when

1. a+b 기본

1-1. JAVA CODE:

public class StudyClassJava extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_empty);
        aPlusB(15,10);
    }
 
 
    private int aPlusB(int a, int b) {
        return a + b;
    }
}

1-2. KOTLIN CODE:

class   StudyClassKotlin : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_empty)
        Log.d("a+b", aPlusB(10,15).toString())
    }
 
    fun aPlusB(a:Int, b:Int) = a+b
}

1-3. 해석:

코틀린에서는 aPlusB(a:Int, b:Int) = a+b와 같이 쉽게 함수를 표현식으로 나타낼 수 있다는 것을 알 수 있다.

2. a+b default parameters 활용

2-1. JAVA CODE:

public class StudyClassJava extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_empty);
        defaultAplusB(15,10);
        defaultAplusB(15);
    }
 
    private int defaultAplusB(Integer... nums) {
        int defaultNum = 10;
        int result = 0;
        if (nums.length == 2) {
            result = nums[0] + nums[1];
        } else if (nums.length == 1) {
            result = nums[0] + defaultNum;
        }
        return result;
    }
}

2-2. KOTLIN CODE(varage):

class StudyClassKotlin : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_empty)
        Log.d("a+b",defaultAplusB(0).toString())
    }
 
    fun defaultAplusB(vararg nums:Int) = if(nums.size==2){nums[0]+nums[1]}else{nums[0]+10}
}
 

2-3. KOTLIN CODE(default parameter):

class   StudyClassKotlin : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_empty)
        Log.d("a+b", aPlusB(10,15).toString())
        Log.d("a+b",defaultAplusB(b=15).toString())
    }
 
    fun defaultAplusB(a:Int=10, b:Int) = a+b
}