A miner for demo during talks/presentations

Miner.java

package org.lobster1234;


import org.apache.commons.codec.digest.DigestUtils;

public class Miner {


    public static void main(String[] args){
        Block block = new Block("185f8db32271fe25f561a6fc938b2e264306ec304eda518007d1764826381969"
                ,"be98c2510e417405647facb89399582fc499c3de4452b3014857f92e6baad9a9"
                ,1.45f,
                System.currentTimeMillis());
        Miner miner = new Miner();
        long nonce = miner.getNonce(block,6);
        System.out.println("Nonce is " + nonce);

    }

    private long getNonce(Block block, int difficulty){
        String data = block.getTo() + block.getFrom() + block.getAmount() + block.getTimestamp();
        StringBuilder target = new StringBuilder();
        for(int i=0;i<difficulty;i++){
            target.append("0");
        }
        System.out.println("Target is " + target + " and initial data is " + data);
        long nonce = 0;
        long start = System.currentTimeMillis();
        while(true){
            String newHashHex = DigestUtils.sha256Hex(data+nonce);
            if(newHashHex.startsWith(target.toString()))
                break;
            else ++nonce;
        }
        System.out.println("For difficultly level " + difficulty + ", it took " + (System.currentTimeMillis()-start) + " milliseconds.");
        return nonce;
    }

}
/**
For now lets just assume 1 block = 1 transaction. In the real world a block = bunch of transactions
*/
class Block{

    private String to;
    private String from;
    private float amount;
    private long timestamp;

    public Block(String to, String from, float amount, long timestamp) {
        this.to = to;
        this.from = from;
        this.amount = amount;
        this.timestamp = timestamp;
    }

    public String getTo() {
        return to;
    }

    public String getFrom() {
        return from;
    }

    public float getAmount() {
        return amount;
    }

    public long getTimestamp() {
        return timestamp;
    }

}