Hist4j is an histogram library for Java that accepts large datasets with any distribution or range with a very small memory footprint. It requires no pre- or post-processing and provides several statistical functions. It adapts to any data distribution, keeping a more or less constant resolution throughout the data range by increasing the resolution where the data is more dense. It can show the accumulative density function for a given data point and the data point that splits the data set at a given percentile.