public class Java1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str1="耿丹计算机Java20170320";
        System.out.println(str1.substring(9));
    }

}

public class Java2 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str="耿丹计算机Java20170320";
        String newStr=str.replaceAll("Java","J2EE");
        System.out.println(newStr);
    }

}

public class Java3 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str="    耿丹 计算机 Java  20170320    ";
        String newStr=str.replaceAll(" ","");
        System.out.println(newStr);
    }
}

public class Java4 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str="420922197509053138";
        System.out.println(str.substring(6,14));
    }

}