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Java SDK

JAR File

Add XDCJava SDK to your project:

To add module dependency to your project, follow the steps below :

  • Go to file menu — project structure — modules — click ‘+’ — select import Gradle Project — select the sub-module folder (git repo which we create) — select “XDC“ folder — finish.
  • You can see the folder in your android/java project.
  • Now, we have to add Module Dependency in the application project builg.gradle file.
  • Put “implementation project (":xdc_sdk")“ in dependencies.
  • Now, we can access the methods of the XDC-android library in the Android app.

Accessing methods of XRC20 in our project.

   XDCClient.getInstance().getTokenInfo(token_address, new TokenDetailCallback() {
                
                @Override
                    public void success(TokenDetailsResponse tokenDetailsResponse)
                    {
                       // you can proceed as you like after getting success response.
                    }
                
                @Override
                public void failure(Throwable t)
                {
                    Toast.makeText(MainActivity.this,t.getMessage(),Toast.LENGTH_LONG).show();
                }

                @Override
                public void failure(String message)
                {
                    Toast.makeText(MainActivity.this,message,Toast.LENGTH_LONG).show();
                }
            });

Now, we can interact with the XRC20 read methods.

name() → string Returns the name of the token.

tokenResponse.getName();

balanceOf(address token,address account) → uint256 Returns the number of tokens owned by the account.

tokenResponse.getBalance();

For write methods, we need to create an instance of XDC Client and need a token owner private key.

Credentials creds = org.web3j.crypto.Credentials.create(PRIVATE_KEY);

transfer(address token, address recipient, uint256 amount) → Moves tokens from the caller’s account to the recipient. It will return a transaction hash.

String trasaction_hash = XDCClient.getInstance().TransferXdc(private_key, sender_address, receiver_address, new BigInteger(String.valueOf(token_totransfer), Long.parseLong(gasprice), Long.parseLong(gaslimit;

approve(address token, address spender, uint256 amount) → Sets amount as the allowance of spender over the caller’s tokens. It will return a transaction hash.

approved_hash = XDCClient.getInstance().approveXRC20Token(Spender_address, privatekey, allownce_spender, value_approve);

To increase Allowance and decrease Allowance, we need an instance of XRC20 and the private key of the owner:

decreaseAllowance(XDCAccount account, address token, address owner, address spender, uint256 subtractedValue)

Automatically decreases the allowance granted to spender by the caller.

It is an alternative to approve.

Emits an Approval event indicating the updated allowance.

approved_hash = XDCClient.getInstance().decreaseAllowance(decrease_owner, decrease_spender, privatekey, decrease_allowance, Spender_address);

XRC20 Token Integration

  • An XRC20 token is a blockchain-based asset with similar functionalities to ether; it can hold value and be sent and received.
  • XRC20 tokens are stored and transferred using XDC addresses and transactions. It uses gas to cover transaction fees.

XRC20 Token

Read methods

name() → string
Returns the name of the token.

symbol() → string
Returns the symbol of the token, usually a shorter version of the name.

decimals() → uint8
Returns the number of decimals used to get its user representation. For example, if decimal equals 2, a balance of 505 tokens should be displayed to a user as 5,05 (505 / 10 ** 2).
Tokens usually opt for a value of 18, imitating the relationship between Ether and Wei.

totalSupply() → uint256
Returns the number of tokens in existence.

balanceOf(address account) → uint256
Returns the number of tokens owned by the account.

allowance(address owner, address spender) → uint256
Returns the remaining number of tokens that the spender will be allowed to spend on behalf of the owner through transferFrom. It is zero by default.

Write methods

approve(address spender, uint256 amount)
Sets amount as the allowance of spender over the caller’s tokens.

transfer(address recipient, uint256 amount)
Moves tokens from the caller’s account to the recipient.

transferFrom(address sender, address recipient, uint256 amount)
Moves tokens from sender to recipient using the allowance mechanism. The amount is deducted from the caller’s allowance.

increaseAllowance(address spender, uint256 addedValue)
Automatically increases the allowance granted to spender by the caller.

decreaseAllowance(address spender, uint256 addedValue)
Automatically decreases the allowance granted to spender by the caller.