➕ Operator di Java

// Operator Aritmatika di Java
public class OperatorAritmatika {
    public static void main(String[] args) {
        int a = 10;
        int b = 3;
        
        // Operasi dasar
        System.out.println("a + b = " + (a + b));  // 13
        System.out.println("a - b = " + (a - b));  // 7
        System.out.println("a * b = " + (a * b));  // 30
        System.out.println("a / b = " + (a / b));  // 3 (integer division)
        System.out.println("a % b = " + (a % b));  // 1 (sisa bagi)
        
        // Untuk hasil desimal, gunakan double
        double c = 10.0;
        double d = 3.0;
        System.out.println("c / d = " + (c / d));  // 3.3333...
        
        // Case nyata: Hitung total belanja
        int hargaBuku = 25000;
        int jumlahBuku = 3;
        int totalBelanja = hargaBuku * jumlahBuku;
        System.out.println("Total: Rp " + totalBelanja);  // Rp 75000
    }
}

// Operator Penugasan
public class OperatorPenugasan {
    public static void main(String[] args) {
        int skor = 100;
        
        // Compound assignment operators
        skor += 20;  // skor = skor + 20; (120)
        System.out.println("Setelah += 20: " + skor);
        
        skor -= 10;  // skor = skor - 10; (110)
        System.out.println("Setelah -= 10: " + skor);
        
        skor *= 2;   // skor = skor * 2; (220)
        System.out.println("Setelah *= 2: " + skor);
        
        skor /= 4;   // skor = skor / 4; (55)
        System.out.println("Setelah /= 4: " + skor);
        
        // Case nyata: Update saldo rekening
        double saldo = 1000000;
        saldo += 500000;   // Deposit
        saldo -= 250000;   // Tarik tunai
        System.out.println("Saldo akhir: Rp " + saldo);
    }
}

// Operator Perbandingan
public class OperatorPerbandingan {
    public static void main(String[] args) {
        int nilai = 85;
        int batasLulus = 70;
        
        // Perbandingan
        boolean lulus = nilai >= batasLulus;
        System.out.println("Lulus: " + lulus);  // true
        
        // Case nyata: Cek umur untuk syarat KTP
        int umur = 18;
        boolean bisaBuatKTP = umur >= 17;
        System.out.println("Bisa buat KTP: " + bisaBuatKTP);
        
        // Cek diskon berdasarkan pembelian
        int totalBelanja = 500000;
        boolean dapatDiskon = totalBelanja > 300000;
        System.out.println("Dapat diskon: " + dapatDiskon);
        
        // Validasi password
        String inputPassword = "12345";
        String correctPassword = "secret123";
        boolean passwordBenar = inputPassword.equals(correctPassword);
        System.out.println("Login berhasil: " + passwordBenar);
    }
}

// Operator Logika
public class OperatorLogika {
    public static void main(String[] args) {
        int umur = 20;
        boolean punyaSIM = true;
        int nilai = 85;
        
        // AND (&&): Semua kondisi harus true
        boolean bisaMenyetir = (umur >= 17) && punyaSIM;
        System.out.println("Bisa menyetir: " + bisaMenyetir);  // true
        
        // OR (||): Salah satu kondisi true sudah cukup
        boolean lulus = (nilai >= 70) || (nilai == 100);
        System.out.println("Lulus: " + lulus);  // true
        
        // NOT (!): Membalik boolean
        boolean belumDewasa = !(umur >= 18);
        System.out.println("Belum dewasa: " + belumDewasa);  // false
        
        // Case nyata: Validasi form registrasi
        String username = "budi123";
        String password = "secret123";
        int umurUser = 20;
        
        boolean usernameValid = username.length() >= 6;
        boolean passwordValid = password.length() >= 8;
        boolean umurValid = umurUser >= 13;
        
        boolean registrasiBerhasil = usernameValid && passwordValid && umurValid;
        System.out.println("Registrasi berhasil: " + registrasiBerhasil);
    }
}

// Operator Increment & Decrement
public class IncrementDecrement {
    public static void main(String[] args) {
        int counter = 0;
        
        // Post-increment
        System.out.println(counter++);  // Print 0, lalu +1
        System.out.println(counter);    // 1
        
        // Pre-increment
        System.out.println(++counter);  // +1 dulu, lalu print 2
        
        // Decrement
        counter--;
        System.out.println(counter);    // 1
        
        // Case nyata: Counter pengunjung website
        int pengunjung = 0;
        pengunjung++;  // User masuk
        pengunjung++;  // User lain masuk
        pengunjung++;  // User lain masuk lagi
        System.out.println("Total pengunjung: " + pengunjung);  // 3
        
        // Stock produk berkurang
        int stock = 10;
        stock--;  // Terjual 1
        stock--;  // Terjual 1 lagi
        System.out.println("Sisa stock: " + stock);  // 8
    }
}