数据类型

public class Welcome{
    public static void main(String[] /*a*/ args){  
    
    //数值型
    /*
        int a=10; //10进制 
        int b=010; //8进制以0开头
        int c=0X10; //16进制以0x或者0X开头
        System.out.println("hello world");
        System.out.println(a);
        System.out.println(b);
        System.out.println(c);
        System.out.println(Integer.toBinaryString(a));//转化为2进制
        System.out.println(Integer.toOctalString(a));//转化为10进制
        System.out.println(Integer.toHexString(a));//转化为16进制
        long a1=200;
        long a2=100;
        long a3=1111111111111111L;
        
        double b1=3.14;  //默认为double
        float b2=6.28F; //转化为float
        double b3=314e-2;
        System.out.println(b3);//科学计数法
        
        float c1=0.1F;
        double c2=1.0/10;
        float c3=1.0F/10;
        System.out.println(c1==c2);//false
        System.out.println(c1==c3);//true
    */
    /*    
    //字符型 单引号
        char c1=‘a‘;   //97
        char c2=‘乔‘;
        char c4=‘\‘‘; //转义字符 ‘ 
        char c5=‘\\‘; //转义字符  \  
        char c6=‘\t‘; // \t 制表符
        char c7=‘\n‘; // \n 换行符
        int i=c1+2;   //字符型运算时当作整数来计算 99
        char c3=(char)(c1+2);//强制转化为字符型  c
        System.out.println(c1);
        System.out.println(c2);
        System.out.println(c4);
        System.out.println(c5);
        System.out.println(c6);
        System.out.println(c7);
        System.out.println(c3);
        System.out.println(i);
        
    //字符串 双引号
        String  s1="absckkkk";
        System.out.println(s1);
        
    //布尔类型
        boolean b=true;
        if (b){
            System.out.println("ok");
        }
    */    
    //类型提升问题
    
       int a=3;
       long b=4;
       double d=5.3;
       int c = a+(int)b; //int c = (int)(a+b);
       float f=(float)(a+d);
       System.out.println(c);//7
       System.out.println(f);//8.3
       
       int money=1000000000;
       int year=10;
       long total=(long)money*year;  //返回的是负数
       System.out.println(total); 
       
       long times=70L*60*24*365*70;
       System.out.println(times); 
    //二进制
       int x=0b0000_0000_0000_0000_0000_0011;//3 下划线分隔符
       System.out.println(x);
               
        
    }
}