Studi Informatika

Panduan Pembelajaran Ilmu Teknologi & Komputer

Wednesday, March 28, 2018

Static Methods

Contoh Algoritma

algorithm: Urutan instruksi program.


Contoh: "Bake sugar cookies"

Mix the dry ingredients.

Cream the butter and sugar.

Beat in the eggs.

Stir in the dry ingredients.

Set the oven temperature.

Set the timer.

Place the cookies into the oven.

Allow the cookies to bake.

Spread frosting and sprinkles onto the cookies.

Permasalahan

Struktur tidak jelas: banyak instruksi yang sulit diingat.

duplikasi:...

Mix the dry ingredients.

Cream the butter and sugar.

Beat in the eggs.

Stir in the dry ingredients.

Set the oven temperature.

Set the timer.

Place the first batch of cookies into the oven.

Allow the cookies to bake.

Set the timer.

Place the second batch of cookies into the oven.

Allow the cookies to bake.

Mix ingredients for frosting.

 Strukturisasi

structured algorithm: Pisahkan menjadi instruksi terpisah.

1  Make the cookie batter.

Mix the dry ingredients.

Cream the butter and sugar.

Beat in the eggs.

Stir in the dry ingredients.



2  Bake the cookies.

Set the oven temperature.

Set the timer.

Place the cookies into the oven.

Allow the cookies to bake.



3  Add frosting and sprinkles.

Mix the ingredients for the frosting.

Spread frosting and sprinkles onto the cookies.

 Menghilangkan Duplikasi
Suatu algoritma yang baik dapat menunjukkan program yang tidak terduplikasi.


1 Make the cookie batter.

Mix the dry ingredients.

...


2a Bake the cookies (first batch).

Set the oven temperature.

Set the timer.

...



2b Bake the cookies (second batch).


3 Decorate the cookies.

...

 Dengan Duplikasi


public class BakeCookies {

    public static void main(String[] args) {

        System.out.println("Mix the dry ingredients.");

        System.out.println("Cream the butter and sugar.");

        System.out.println("Beat in the eggs.");

        System.out.println("Stir in the dry ingredients.");

        System.out.println("Set the oven temperature.");

        System.out.println("Set the timer.");

        System.out.println("Place a batch of cookies into the oven.");

        System.out.println("Allow the cookies to bake.");

        System.out.println("Set the oven temperature.");

        System.out.println("Set the timer.");

        System.out.println("Place a batch of cookies into the oven.");

        System.out.println("Allow the cookies to bake.");

        System.out.println("Mix ingredients for frosting.");

        System.out.println("Spread frosting and sprinkles.");

    }

}

Static Methods


static method: Suatu nama group dari statement.

Menunjukkan struktur program

Menghilangkan duplikasi


dekomposisi:
memecahkan menjadi methods



Menuliskan static method seperti

menambahkan instruksi baru.


Menggunakan Static Methods

1. Rancang Algoritma.

Lihat dari struktur masalah, dan lihat duplikasi.

Lihat tujuan dari solusi masalah.



2. Tuliskan method nya.

Atur instruksi ke dalam group dan berikan namanya.



3. Jalankan.

Dimulai dari main method.

 Perancangan Algoritma


// This program displays a delicious recipe for baking cookies.

public class BakeCookies2 {

    public static void main(String[] args) {

        // Step 1: Make the cake batter.

        System.out.println("Mix the dry ingredients.");

        System.out.println("Cream the butter and sugar.");

        System.out.println("Beat in the eggs.");

        System.out.println("Stir in the dry ingredients.");



        // Step 2a: Bake cookies (first batch).

        System.out.println("Set the oven temperature.");

        System.out.println("Set the timer.");

        System.out.println("Place a batch of cookies into the oven.");

        System.out.println("Allow the cookies to bake.");



        // Step 2b: Bake cookies (second batch).

        System.out.println("Set the oven temperature.");

        System.out.println("Set the timer.");

        System.out.println("Place a batch of cookies into the oven.");

        System.out.println("Allow the cookies to bake.");



        // Step 3: Decorate the cookies.

        System.out.println("Mix ingredients for frosting.");

        System.out.println("Spread frosting and sprinkles.");

    }

}

Pendeklarasian Method

Berikan nama untuk setiap method



Syntax:


public static void name() {
   
statement;
   
statement;
   
...
   
statement;
}

Contoh:

public static void printWarning() {
    System.out.println("This product causes cancer");
   
System.out.println("in lab rats and humans.");
}

 Memanggil Method
Jalankan



Syntax:


  name();


Kita bisa memanggil method berkali-kali.


Contoh:


  printWarning();


Output:


  This product causes cancer

  in lab rats and humans.

 Program dengan static method


public class FreshPrince {

    public static void main(String[] args) {

        rap();                 // Calling (running) the rap method

        System.out.println();

        rap();                 // Calling the rap method again

    }


    // This method prints the lyrics to my favorite song.

    public static void rap() {

        System.out.println("Now this is the story all about how");

        System.out.println("My life got flipped turned upside-down");

    }

}


Output:


Now this is the story all about how

My life got flipped turned upside-down


Now this is the story all about how

My life got flipped turned upside-down

Final Program


// This program displays a delicious recipe for baking cookies.

public class BakeCookies3 {

    public static void main(String[] args) {

        makeBatter();

        bake();       // 1st batch

        bake();       // 2nd batch

        decorate();

    }

    

    // Step 1: Make the cake batter.

    public static void makeBatter() {

        System.out.println("Mix the dry ingredients.");

        System.out.println("Cream the butter and sugar.");

        System.out.println("Beat in the eggs.");

        System.out.println("Stir in the dry ingredients.");

    }


    // Step 2: Bake a batch of cookies.

    public static void bake() {

        System.out.println("Set the oven temperature.");

        System.out.println("Set the timer.");

        System.out.println("Place a batch of cookies into the oven.");

        System.out.println("Allow the cookies to bake.");

    }

   

    // Step 3: Decorate the cookies.

    public static void decorate() {

        System.out.println("Mix ingredients for frosting.");

        System.out.println("Spread frosting and sprinkles.");

    }

}

Methods Memanggil Methods


public class MethodsExample {

    public static void main(String[] args) {

        message1();

        message2();

        System.out.println("Done with main.");

    }


    public static void message1() {

        System.out.println("This is message1.");

    }


    public static void message2() {

        System.out.println("This is message2.");

        message1();

        System.out.println("Done with message2.");

    }

}


Output:

This is message1.

This is message2.

This is message1.

Done with message2.

Done with main.

Aliran Kontrol
Saat suatu method dipanggil...

berpindah" ke method tersebut dan menjalankannya. lalu

kembali" ke poin sebelumnya


}


Kapan Menggunakan Methods

Gunakan static method jika:

statements berhubungan secara struktural, dan/atau

Berulang-ulang dipanggil / terduplikasi.



Jangan gunakan static methods jika:

Hanya satu println

Hanya baris kosong
         Tidak ada perulangan atau duplikasi




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