public class zuoye {

    /**
     * @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(1));
    }
}

public class zuoye1 {

    /**
     * @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("替换后："+newStr);
    }

}

public class zuoye2 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str1="耿丹 计算机 Java 2017320";
        String newStr = str1.replaceAll(" ", "");
        System.out.println("替换后："+newStr);
    }

}

public class zuoye3 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str = "11010919990118xxxx";
        System.out.println(str.substring(6,13));
    }

}