2

There is BizzleTokenSale contract.

pragma solidity ^0.4.2;

import "./BizzleToken.sol";

contract BizzleTokenSale {

address admin;

BizzleToken public tokenContract;
uint256 public tokenPrice;
uint256 public tokensSold;


event Sell(address _buyer, uint256 _amount);

function BizzleTokenSale(BizzleToken _tokenContract, uint256 _tokenPrice) public {
    admin = msg.sender;
    tokenContract = _tokenContract;
    tokenPrice = _tokenPrice;


}

function multiply(uint x, uint y) internal pure returns (uint z) {

    require(y == 0 || (z = x * y) / y == x);

}

function buyTokens(uint256 _numberOfTokens) public payable {

    // Require that value is equal
    require(msg.value == multiply(_numberOfTokens, tokenPrice));

    // Require token contract has enough tokens
    require(tokenContract.balanceOf(this) >= _numberOfTokens);

    // Require transfer is successfull
    require(tokenContract.transfer(msg.sender, _numberOfTokens));

    // Keep track tokensSold
    tokensSold += _numberOfTokens;

    // track Sell event
    Sell(msg.sender, _numberOfTokens);
}

 function endSale() public {
    require(msg.sender == admin);
    require(tokenContract.transfer(admin, tokenContract.balanceOf(this)));
    admin.transfer(address(this).balance);
}
}

And there is BizzleToken.sol

pragma solidity ^0.4.2;


contract BizzleToken {

string public name = "Bizzle Token";
string public symbol = "BIZ";
string public standart = "Bizzle Token v1.0";
uint256 public totalSupply;

mapping(address => uint256) public balanceOf;
mapping(address => mapping(address => uint256)) public allowance;


event Transfer(
    address indexed _from,
    address indexed _to,
    uint256 _value
);

event Approval(
    address indexed _owner,
    address indexed _spender,
    uint256 _value
);

function BizzleToken(uint256 _initialSupply) public {
    balanceOf[msg.sender] = _initialSupply;
    totalSupply = _initialSupply;

}

function transfer(address _to , uint256 _value) public returns (bool success){

    // Exception does not have enough tokens
    require(balanceOf[msg.sender] >= _value);

    balanceOf[msg.sender] -= _value;

    balanceOf[_to] += _value;

    Transfer(msg.sender, _to, _value);


    return true;

}


function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {

     // check _from token balance
    require(_value <= balanceOf[_from]);
     // check allowance is big enough
    require(_value <= allowance[_from][msg.sender]);

    balanceOf[_from] -= _value;
    balanceOf[_to] += _value;

    allowance[_from][msg.sender] -= _value;

    Transfer(_from,_to,_value);

    return true;

}


function approve(address _spender, uint256 _value) public returns (bool success) {

    allowance[msg.sender][_spender] = _value;

    Approval(msg.sender,_spender, _value);

    return true;


}

function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
    return allowance[_owner][_spender];
}

}

I have tested with JavaScript it works.

App = {
web3Provider: null,
contracts: {},
account: '0x0',
loading: false,
tokenPrice: 1000000000000000,
tokensSold: 0,
tokensAvailable: 750000,

init: function() {
console.log("App initialized...")
return App.initWeb3();
},

**/// Buy tokens Function**

buyTokens: function() {
$('#content').hide();
$('#loader').show();
var numberOfTokens = $('#numberOfTokens').val();
App.contracts.BizzleTokenSale.deployed().then(function(instance) {
  return instance.buyTokens(numberOfTokens, {
    from: App.account,
    value: numberOfTokens * App.tokenPrice,
    gas: 500000 // Gas limit
  });
}).then(function(result) {
  console.log("Tokens bought...")
  $('form').trigger('reset') // reset number of tokens in form
  // Wait for Sell event
});

}

My question is How can I intract to smart Contract with Java ?

Here is my java class.

    public TransactionReceipt buyTokens(Uint256 _amount) throws IOException, TransactionException {
    Function function = new Function("buyTokens", Arrays.<Type>asList(_amount), Collections.<TypeReference<?>>emptyList());
    return executeTransaction(function);
    }

When I call this java function error was in Etherscan.

Ether is not sending to smart contract.

  • How Can I do this step in Java ? return instance.buyTokens(numberOfTokens, { from: App.account, value: numberOfTokens * App.tokenPrice, gas: 500000 // Gas limit }); – Nizomjon Hajiev Nov 27 '18 at 3:20
1

Since the function is payable; you can transmit the value as well.

Without value, function seems to be reverting at this line :

function buyTokens(uint256 _numberOfTokens) public payable {

    // Require that value is equal
    require(msg.value == multiply(_numberOfTokens, tokenPrice));

(value would be 0 or null)

Try this in Java :

//Calculate "value" like it is done in JS code that you mentioned. And provide that as parameter.
public TransactionReceipt buyTokens(Uint256 _amount, BigInteger value) throws IOException, TransactionException {
    Function function = new Function("buyTokens", Arrays.<Type>asList(_amount), Collections.<TypeReference<?>>emptyList());
    return executeTransaction(function, value);
    }

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.