java03数据类型

避免浮点数比较

float a1 = 23232323232323f;
float a2 = a1 + 1;
System.out.println(a1==a2);

char和string

char a = 'z';
String a0 = "z";

long a3 = 123l;
float a4 = 123f;
//二进制0b 十进制 八进制0 十六进制0x
int i = 10;
int i1 = 010;
int i2 = 0x10;

char b = '\u0063';//unicode编码c

转义字符

// \t 制表符
// \n 换行

地址

String sa = new String(original: "hello wor1d");
String sb = new String(original: "hello wor1d");
System.out.println(sa==sb);//false

变量转换

int i = 128;
byte b = (byte)i;
//强制转换 从高到低；从低到高可以自动转换
int m =10_0000_0000;
int y = 20;
int end = m*y;//-147483480,溢出
long end2 = m*y;//依旧溢出，因为先计算再转换
long end3 = m*((long)y);//正常