How to list Java Properties? Properties can be written to PrintWriter or PrintStream as we demonstrate in the example below.

java.util.Properties has two list() methods that write to different targets:

• void list(PrintStream out)
  Prints all properties to given output stream.
• void list(PrintWriter out)
  Prints all properties to given writer.

In the following example we create a new Properties object and fill with two properties. Then we print them using list(PrintStream) and passing System.out as our target:

package com.farenda.java.util;

import java.util.Properties;

public class PropertiesList {

    public static void main(String[] args) {
        Properties props = new Properties();
        props.setProperty("connectionTime", "1200");
        props.setProperty("maxThreads", "50");

        props.list(System.out);
    }
}

As you can see, when defining property, both key and value are of String type.

Running the code produces the following output:

-- listing properties --
connectionTime=1200
maxThreads=50