Operasi Data Transaksi

public class Main {

  // Mock Firebase classes for demonstration
  static class MockFirebaseDatabase {
    private Integer value = 0; // Simulate data at a path
    public Integer get() { return value; }
    public void set(Integer val) { value = val; }

    public interface TransactionHandler {
      TransactionResult doTransaction(MutableData currentData);
    }

    public static class MutableData {
      private Integer data;
      public MutableData(Integer data) { this.data = data; }
      public Integer getValue() { return data; }
      public void setValue(Integer data) { this.data = data; }
    }

    public static class TransactionResult {
      private boolean success;
      private MutableData newData;
      private TransactionResult(boolean success, MutableData newData) {
        this.success = success;
        this.newData = newData;
      }
      public static TransactionResult success(MutableData newData) {
        return new TransactionResult(true, newData);
      }
      public static TransactionResult abort() {
        return new TransactionResult(false, null);
      }
      public boolean isSuccess() { return success; }
      public MutableData getNewData() { return newData; }
    }

    public void runTransaction(TransactionHandler handler) {
      // Simulate read, modify, and retry logic
      MutableData currentData = new MutableData(this.get());
      TransactionResult result = handler.doTransaction(currentData);

      if (result.isSuccess()) {
        this.set(result.getNewData().getValue());
        System.out.println("Transaction committed. New value: " + this.get());
      } else {
        System.out.println("Transaction aborted.");
      }
    }
  }

  public static void main(String[] args) {
    MockFirebaseDatabase counterRef = new MockFirebaseDatabase();
    counterRef.set(5); // Initial value

    counterRef.runTransaction(new MockFirebaseDatabase.TransactionHandler() {
      @Override
      public MockFirebaseDatabase.TransactionResult doTransaction(MockFirebaseDatabase.MutableData currentData) {
        Integer currentValue = currentData.getValue();
        if (currentValue == null) {
          currentValue = 0;
        }
        currentData.setValue(currentValue + 1);
        return MockFirebaseDatabase.TransactionResult.success(currentData);
      }
    });
  }
}

public class Main {

  // Mock Firebase classes (repeated for full program requirement)
  static class MockFirebaseDatabase {
    private Integer value = 0;
    public Integer get() { return value; }
    public void set(Integer val) { value = val; }

    public interface TransactionHandler {
      TransactionResult doTransaction(MutableData currentData);
    }

    public static class MutableData {
      private Integer data;
      public MutableData(Integer data) { this.data = data; }
      public Integer getValue() { return data; }
      public void setValue(Integer data) { this.data = data; }
    }

    public static class TransactionResult {
      private boolean success;
      private MutableData newData;
      private TransactionResult(boolean success, MutableData newData) {
        this.success = success;
        this.newData = newData;
      }
      public static TransactionResult success(MutableData newData) {
        return new TransactionResult(true, newData);
      }
      public static TransactionResult abort() {
        return new TransactionResult(false, null);
      }
      public boolean isSuccess() { return success; }
      public MutableData getNewData() { return newData; }
    }

    public void runTransaction(TransactionHandler handler) {
      MutableData currentData = new MutableData(this.get());
      TransactionResult result = handler.doTransaction(currentData);

      if (result.isSuccess()) {
        this.set(result.getNewData().getValue());
        System.out.println("Transaction committed. New value: " + this.get());
      } else {
        System.out.println("Transaction aborted.");
      }
    }
  }

  public static void main(String[] args) {
    MockFirebaseDatabase statusRef = new MockFirebaseDatabase();
    statusRef.set(1); // 1 = Active, 0 = Inactive

    // Try to change status, but abort if it's already Inactive (0)
    statusRef.runTransaction(new MockFirebaseDatabase.TransactionHandler() {
      @Override
      public MockFirebaseDatabase.TransactionResult doTransaction(MockFirebaseDatabase.MutableData currentData) {
        Integer status = currentData.getValue();
        if (status != null && status == 0) {
          System.out.println("Status is already Inactive. Aborting transaction.");
          return MockFirebaseDatabase.TransactionResult.abort();
        }
        // Change status to 0 (Inactive)
        currentData.setValue(0);
        return MockFirebaseDatabase.TransactionResult.success(currentData);
      }
    });
  }
}