public class BufferExample {
    public static void main(String[] args) {
        StringBuffer sb = new StringBuffer("Hello");
        sb.append(" Java");
        sb.append(" World!");
        System.out.println(sb); // Hello Java World!
    }
}

public class BuilderExample {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("Hello");
        sb.append(" Java");
        sb.append(" World!");
        System.out.println(sb); // Hello Java World!
    }
}

public class PerformanceTest {
    public static void main(String[] args) {
        long start1 = System.nanoTime();
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < 100000; i++) sb.append("A");
        System.out.println("StringBuilder: " + (System.nanoTime() - start1));

        long start2 = System.nanoTime();
        StringBuffer sbf = new StringBuffer();
        for(int i = 0; i < 100000; i++) sbf.append("A");
        System.out.println("StringBuffer: " + (System.nanoTime() - start2));
    }
}

#کاربرـپیشرفته

🆔 @javapro_ir
🆔 @group_javapro

public class StringConcatExample {
    public static void main(String[] args) {
        String result = "";
        for (int i = 0; i < 5; i++) {
            result = result + i;
        }
        System.out.println(result);
    }
}

01234

public class ConcatExample {
    public static void main(String[] args) {
        String result = "";
        for (int i = 0; i < 5; i++) {
            result = result.concat(String.valueOf(i));
        }
        System.out.println(result);
    }
}

return new String(this.value + otherValue);

public class StringBuilderExample {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 5; i++) {
            sb.append(i);
        }
        System.out.println(sb.toString());
    }
}

public class PerformanceTest {
    public static void main(String[] args) {
        long start1 = System.nanoTime();
        String s = "";
        for (int i = 0; i < 10000; i++) {
            s += i;
        }
        long duration1 = System.nanoTime() - start1;

        long start2 = System.nanoTime();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 10000; i++) {
            sb.append(i);
        }
        long duration2 = System.nanoTime() - start2;

        System.out.println("Using '+': " + duration1);
        System.out.println("Using StringBuilder: " + duration2);
    }
}

#کاربرـحرفهـای

🆔 @javapro_ir
🆔 @group_javapro

class Engine {
    void start() {
        System.out.println("Engine started!");
    }
}

class Car {
    private Engine engine = new Engine(); // وابستگی مستقیم!

    void drive() {
        engine.start();
        System.out.println("Car is moving!");
    }
}

class Engine {
    void start() {
        System.out.println("Engine started!");
    }
}

class Car {
    private Engine engine;

    // وابستگی از بیرون تزریق می‌شود
    public Car(Engine engine) {
        this.engine = engine;
    }

    void drive() {
        engine.start();
        System.out.println("Car is moving!");
    }
}

public class Main {
    public static void main(String[] args) {
        Engine engine = new Engine();
        Car car = new Car(engine); // تزریق وابستگی
        car.drive();
    }
}

class Car {
    private Engine engine;

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    void drive() {
        engine.start();
        System.out.println("Car is moving!");
    }
}

class MockEngine extends Engine {
    void start() {
        System.out.println("Mock engine started (for testing)");
    }
}

public class Test {
    public static void main(String[] args) {
        Car car = new Car(new MockEngine());
        car.drive(); // تست بدون اجرای موتور واقعی
    }
}

@Component
class Engine {
    void start() {
        System.out.println("Engine started!");
    }
}

@Component
class Car {
    private final Engine engine;

    @Autowired
    public Car(Engine engine) {
        this.engine = engine;
    }

    void drive() {
        engine.start();
        System.out.println("Car is moving!");
    }
}

#کاربرـپیشرفته

🆔 @javapro_ir
🆔 @group_javapro

import com.fasterxml.jackson.databind.ObjectMapper;

class User {
    public String name;
    public int age;
}

public class JacksonExample {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();

        // شیء جاوا به JSON
        User user = new User();
        user.name = "Saleh";
        user.age = 25;
        String json = mapper.writeValueAsString(user);
        System.out.println("JSON: " + json);

        // JSON به شیء جاوا
        User newUser = mapper.readValue(json, User.class);
        System.out.println("Name: " + newUser.name);
    }
}

JSON: {"name":"Saleh","age":25}
Name: Saleh

import com.google.gson.Gson;

class User {
    String name;
    int age;
}

public class GsonExample {
    public static void main(String[] args) {
        Gson gson = new Gson();

        // شیء جاوا به JSON
        User user = new User();
        user.name = "Saleh";
        user.age = 25;
        String json = gson.toJson(user);
        System.out.println("JSON: " + json);

        // JSON به شیء جاوا
        User newUser = gson.fromJson(json, User.class);
        System.out.println("Name: " + newUser.name);
    }
}

JSON: {"name":"Saleh","age":25}
Name: Saleh

#کاربرـحرفهـای

🆔 @javapro_ir
🆔 @group_javapro