Getting Started

Ta4j is an open source Java library for technical analysis. It provides the basic components for creation, evaluation and execution of trading strategies.

About technical analysis:

Eclipse setup

Ta4j is available on Maven. You can create a Maven project in eclipse and add the ta4j dependency to the pom.xml file.

<dependency>
  <groupId>org.ta4j</groupId>
  <artifactId>ta4j-core</artifactId>
  <version>0.15</version>
</dependency>

Another way could be to clone this git repository or to simply download this library and add the source code to your existing eclipse project.

Getting started with ta4j

In this quick example we will backtest a trading strategy over a price time series.

At the beginning we just need a time series.

// Creating a time series (from any provider: CSV, web service, etc.)
BarSeries series = new BaseBarSeriesBuilder().withName("AXP_Stock").build();

After createing a TimeSeries we can add OHLC data and volume to the series:

// adding open, high, low, close and volume data to the series
series.addBar(ZonedDateTime.now(), 105.42, 112.99, 104.01, 111.42, 1337);

See the Bar Series and Bars section to learn about time series and to know how you can construct one.

Using indicators

We can calculate indicator over this bar series, in order to forecast the direction of prices through the study of past market data.

// Getting the close price of the ticks
Num firstClosePrice = series.getBar(0).getClosePrice();
System.out.println("First close price: " + firstClosePrice.doubleValue());
// Or within an indicator:
ClosePriceIndicator closePrice = new ClosePriceIndicator(series);
// Here is the same close price:
System.out.println(firstClosePrice.isEqual(closePrice.getValue(0))); // equal to firstClosePrice

// Getting the simple moving average (SMA) of the close price over the last 5 ticks
SMAIndicator shortSma = new SMAIndicator(closePrice, 5);
// Here is the 5-ticks-SMA value at the 42nd index
System.out.println("5-ticks-SMA value at the 42nd index: " + shortSma.getValue(42).doubleValue());

// Getting a longer SMA (e.g. over the 30 last ticks)
SMAIndicator longSma = new SMAIndicator(closePrice, 30);

Ta4j includes more than 130 technical indicators.

Building a trading strategy

Then we have to build our trading strategy. It is made of two trading rules: one for entry, the other for exit.

// Buying rules
// We want to buy:
//  - if the 5-ticks SMA crosses over 30-ticks SMA
//  - or if the price goes below a defined price (e.g $800.00)
Rule buyingRule = new CrossedUpIndicatorRule(shortSma, longSma)
        .or(new CrossedDownIndicatorRule(closePrice, 800d));

// Selling rules
// We want to sell:
//  - if the 5-ticks SMA crosses under 30-ticks SMA
//  - or if the price loses more than 3%
//  - or if the price earns more than 2%
Rule sellingRule = new CrossedDownIndicatorRule(shortSma, longSma)
        .or(new StopLossRule(closePrice, 3.0))
        .or(new StopGainRule(closePrice, 2.0));

Strategy strategy = new BaseStrategy(buyingRule, sellingRule);

Ta4j comes with a set of basic trading rules/strategies which can be combined using boolean operators.

Backtesting/running our juicy strategy

The backtest step is pretty simple:

// Running our juicy trading strategy...
BarSeriesManager manager = new BarSeriesManager(series);
TradingRecord tradingRecord = manager.run(strategy);
System.out.println("Number of trades for our strategy: " + tradingRecord.getTradeCount());

Analyzing our results

Here is how we can analyze the results of our backtest:

// Getting the profitable trades ratio
AnalysisCriterion profitTradesRatio = new AverageProfitableTradesCriterion();
System.out.println("Profitable trades ratio: " + profitTradesRatio.calculate(series, tradingRecord));
// Getting the reward-risk ratio
AnalysisCriterion rewardRiskRatio = new RewardRiskRatioCriterion();
System.out.println("Reward-risk ratio: " + rewardRiskRatio.calculate(series, tradingRecord));

// Total profit of our strategy
// vs total profit of a buy-and-hold strategy
AnalysisCriterion vsBuyAndHold = new VersusBuyAndHoldCriterion(new TotalProfitCriterion());
System.out.println("Our profit vs buy-and-hold profit: " + vsBuyAndHold.calculate(series, tradingRecord));

Trading strategies can be easily compared according to a set of analysis criteria.

Going further

Ta4j can also be used for live trading with more complicated strategies. Check out the rest of the documentation and the examples.