contracts.sol

pragma solidity >= 0.4.22 < 0.6.0;

contract A {
    uint256 value;
    
    constructor(uint256 _value) public {
        value = _value;
    }
    
    function getValue() external view returns(uint256) {
        return value;
    }
}

interface IA {
     function getValue() external view returns(uint256);
}

contract FactoryA {
    A[] private contractList;
    
    function createContractA(uint256 _value) external {
        A a = new A(_value);
        contractList.push(a);
    }
    
    function getContractListAddresses() external view returns (A[] memory) {
        return contractList;
    }
}

interface IFactoryA {
    function createContractA(uint256 _value) external;
    function getContractListAddresses() external view returns (A[] memory);
}


contract B {
    
    event newContractACreated(uint256 _value);
    IFactoryA factoryContract;
    
    constructor(address _factoryContractAddress) public {
        factoryContract = IFactoryA(_factoryContractAddress);
    }
    
    function createContractA(uint256 _value) public {
        factoryContract.createContractA(_value);
        emit newContractACreated(_value);
    }
    
}