java判断是否数字

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和一些零碎的东西

package cn;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class Test {
   public static void main(String[] args) {
       /*String str = ",";
       String strSub = str.substring(1, str.length());*/
       //System.out.println(str.substring(1, str.length()));

       /*Map map = new HashMap();
       map.put("123hjy", "haahha");

       System.out.println(map.get("123hjy"));*/
       //System.out.println(isDouble("4523.552"));//isDouble isInteger
       /*String strs = "abc";
       String[] hao = strs.split(",");
       for(int i=0;i<hao.length;i++){
           System.out.println(hao[i] + "@");
       }*/
       /*double num = 25.;
       //System.out.println(isDouble("25."));
       SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
       System.out.println(dateFormat.format(new Date()));
       System.out.println(new Random().nextInt(99));
       int n = 1;
       for(int i=0;i<n;i++){
           System.out.println("hao");
           if(n==1){
               n++;
           }
       }*/
       /*Date now = new Date();
       System.out.println(now.getDay());
       now.setDate(now.getDate()+650);
       SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
       System.out.println(format.format(now));*/
       /*String str = "00474";
       System.out.println(str.length());
       System.out.println(Integer.parseInt(str));
       SimpleDateFormat dateFormat = new SimpleDateFormat("yyMMdd");
       System.out.println(dateFormat.format(new Date()));*/

       /*String str = "100041208160159";
       int hao = Integer.parseInt(str.substring(11, 15));
       System.out.println(hao);
       System.out.println(str.substring(11, 15));*/
       String you = "";
       System.out.println(you.trim());
   }
   /**
   * 判断是否是数字类型
   * @param str
   * @return
   */
   public static boolean isInteger(String str){
       boolean flag = true;
       for(int i=0;i<str.length();i++){
           if (!Character.isDigit(str.charAt(i))){
               flag = false;
               break;
           }
       }
       return flag;
   }
   /**
   * 判断是否是数字类型
   * @param str
   * @return
   */
   public static boolean isDouble(String str){
       try
       {
           Double.parseDouble(str);
           return true;
       }catch(Exception ex){
           return false;
       }
   }
}