关于怎样控制double后小数点

import java.text.DecimalFormat;

public class hjj {
    public static void main(String[] args) {
                DecimalFormat df = new DecimalFormat( "0.0000 ");
                double d1 = 1.0;
                double d2 = 4.56789;
                System.out.println(df.format(d1));
                System.out.println(df.format(d2));
         }
}

算是找到了