


How to Populate JFreeChart TimeSeriesCollection from MySQL DB?
Introduction
JFreeChart TimeSeriesCollection is a data structure used to hold time series data for visualization in charts. When attempting to populate this collection from a MySQL database, challenges may arise in accurately displaying the data. Here's a detailed explanation of how to overcome these challenges and generate a correct chart:
Problem
In the given code, the issue lies in the conversion from String to Date. The code uses SimpleDateFormat to convert the result from the SQL query to a Date object. However, precision may be lost during this conversion, leading to incorrect display of time values in the chart.
Solution
To resolve this issue, the following steps are recommended:
- Ensure that the MySQL database stores the datetime data in the correct format, preferably as a Timestamp or DateTime data type.
- In the code, convert the String result from the SQL query to a Timestamp object using Timestamp.valueOf(stringDate).
- Add the Timestamp object to the TimeSeries as a new data point using TimeSeries.addOrUpdate(timestamp, value).
By implementing these changes, the TimeSeriesCollection will accurately display the datetime values without loss of precision, resulting in a correct visualization of the time series data.
Additional Tips
- Use JDBCXYDataset: JDBCXYDataset is a specialized class in JFreeChart that is designed to connect to a database and retrieve time series data. It provides a simpler and more efficient way to populate the TimeSeriesCollection.
- Query Optimization: Optimize the SQL query to retrieve only the relevant data within the desired time range.
- Data Validation: Perform data validation before adding to the TimeSeriesCollection to ensure data integrity.
- Chart Customization: Customize the chart appearance, including axis labels, title, and plot style to enhance readability and visual appeal.
The above is the detailed content of How to Populate JFreeChart TimeSeriesCollection from MySQL DB with Accurate Time Values?. For more information, please follow other related articles on the PHP Chinese website!

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