The best Java idiom I've seem for simulating keyword arguments in constructors is the Builder pattern, described in Effective Java 2nd Edition.

The basic idea is to have a Builder class that has setters (but usually not getters) for the different constructor parameters. There's also a build() method. The Builder class is often a (static) nested class of the class that it's used to build. The outer class's constructor is often private.

The end result looks something like:

public class Foo {
  public static class Builder {
    public Foo build() {
      return new Foo(this);
    }

    public Builder setSize(int size) {
      this.size = size;
      return this;
    }

    public Builder setColor(Color color) {
      this.color = color;
      return this;
    }

    public Builder setName(String name) {
      this.name = name;
      return this;
    }

    // you can set defaults for these here
    private int size;
    private Color color;
    private String name;
  }

  public static Builder builder() {
      return new Builder();
  }

  private Foo(Builder builder) {
    size = builder.size;
    color = builder.color;
    name = builder.name;
  }

  private final int size;
  private final Color color;
  private final String name;

  // The rest of Foo goes here...
}

To create an instance of Foo you then write something like:

Foo foo = Foo.builder()
    .setColor(red)
    .setName("Fred")
    .setSize(42)
    .build();

The main caveats are:

1. Setting up the pattern is pretty verbose (as you can see). Probably not worth it except for classes you plan on instantiating in many places.
2. There's no compile-time checking that all of the parameters have been specified exactly once. You can add runtime checks, or you can use this only for optional parameters and make required parameters normal parameters to either Foo or the Builder's constructor. (People generally don't worry about the case where the same parameter is being set multiple times.)

You may also want to check out this blog post (not by me).

It might - if you could pass a map into a method, which would look up the map's keyed entries. It would require an inline, typeless map declaration, which wouldn't be very useful outside of this kind of limited scope - and since it'd be very limited, I'd end up saying "No, not required." If you want the facility, use Python. If you want the capability in a JVM, use Jython or JRuby.

No there is no kwargs in java. Instead you can something similar to your function by using java varargs to save them as java properties.

You do you can something like this:

useKwargs("param1=value1","param2=value2");

Example code:

public void useKwargs(String... parameters) {

        Properties properties = new Properties();

        for (String param : parameters) {
            String[] pair = parseKeyValue(param);

            if (pair != null) {
                properties.setProperty(pair[0], pair[1]);
            }

        }

        doSomething(properties);
    }

    public void doSomething(Properties properties) {
        /**
         * Do something using using parameters specified in the properties
         */

    }

    private static String[] parseKeyValue(String token) {
        if (token == null || token.equals("")) {
            return null;
        }

        token = token.trim();

        int index = token.indexOf("=");

        if (index == -1) {
            return new String[] { token.trim(), "" };
        } else {
            return new String[] { token.substring(0, index).trim(),
                    token.substring(index + 1).trim() };
        }

    }