数字(基础)

package shuzi;

import  java.text. DecimalFormat;
import  java.math.BigInteger;
import  java.math.BigDecimal;
import  java.util.Random;
public class ssssss {

    public static void main(String[] args) {
        
        int i =123;
        
        long l = i;
        
      int intl = (int)l;
        
        //数字包装类
        
        Integer ig = new Integer("2");
        
        int int3 = ig.intValue();
        
        System.out.println("ig =" +int3);
        
        //数据转换的静态方法,常用方法
        
        Integer.parseInt("123");                                             //int型
        
        int int5=Integer.MAX_VALUE;
        int int6=Integer.MIN_VALUE;
        
        System.out.println("Integer.MAX_VALUE=" +int5);
        System.out.println("Integer.MIN_VALUE="+int6);
        
        Long long1=new Long("222");
        
        Long.parseLong("1234568");                                                           //long型
        System.out.println("long1="+long1);
        long lon1 =Long.parseLong("2222222");
        System.out.println("lon1="+lon1);
        
        
        double dou1= Double.parseDouble("1234.111");                           //double型
        System.out.println("dou1="+dou1);
        double dou2= Double.parseDouble("1234");
        System.out.println("dou2="+dou2);
        
        //字符串(忽略大小写)等于"true"，转成true,其他全转成false
        
        boolean t = Boolean.parseBoolean("tRUe");                                //  boolean型
        System.out.println("t="+t);
        
        //数字格式化  随机数
        //0 - 数字，自动显示0
       //# - 数字，不自动补0，
        
        DecimalFormat df =new DecimalFormat("0000.00");
        
        System.out.println("123.456=" +df.format(123.456));
        
        df.applyPattern("#.##");
        
        System.out.println("123.456  #.##=" +df.format(123.456));
        System.out.println("5,123,789.456=" +df.format(123.456));
        df.applyPattern("#.####");
        
        System.out.println("123.456 =" +df.format(123.456));
        
        df.applyPattern("#,###,###.##");
        System.out.println("5,123,789.456=" +df.format(12333333.456));
        
        df.applyPattern("##.#%");
        
        System.out.println("0.78="+df.format(0.7863));
        
        df.applyPattern("##%");
        
        System.out.println("0.78="+df.format(0.786));
        
        df.applyPattern("##.#%");
        
        System.out.println("0.78="+((0.78*100)+"%") +" "+ df.format(0.7863));
        
        //数学运算
        
        System.out.println(""+Math.PI);   //π的表示
        
        //取整函数
        
        double dd =123.45;
        
        System.out.println("ceil="+Math.ceil(dd));               //大于123.45的最小整数，小数的上限值
        
        System.out.println("floor="+Math.floor(dd));            //小于123.45的最小整数，小数的下限值
        
        //四舍五入
        
        System.out.println("round"+Math.round(dd));
        
        //随机数   0-1之间的数字，随机数种子，默认使用计算机的当前时间做种子
        for(int a =0;a<10;a++)
        {
        System.out.println("随机数"+Math.random());    //用for循环随机产生10组数字
        }
        for(int b =0;b<10;b++)
        {
        System.out.println("随机数="+Math.ceil(Math.random()*100));  
        }
        //实例化，制定种子
        Random rm = new Random(123);
        
        for (int j =0; j<10;j++)
        {
            System.out.println("Random随机数="+rm.nextDouble());
            
        }
        for (int v =0; v<10;v++)
        {
            System.out.println("Random随机数="+rm.nextInt(10));
        }
        
        BigInteger gi = new BigInteger ("1234566543312");
        BigDecimal bb = new BigDecimal("12345.1112234");
        
        
        
    }

}