Java中国語コードの問題

import java.io.UnsupportedEncodingException;


public class t {

	/**
	 * @param args     Windows preferences general WorkSpace   
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
	
		String str = " ";
		
		byte[] bytes = null;
		try {
			bytes = str.getBytes("GBK"); //2
			System.out.println(bytes.length);
			
			bytes = str.getBytes("UTF-8");//3
			System.out.println(bytes.length);
			
			//str = " "             
			//         1      
			bytes = str.getBytes("ISO8859_1");
			System.out.println(bytes.length);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}