int a 3; int b 2; System.out.println(a b); System.out.println(a - b); System.out.println(a * b); //除法會(huì)下取整 System.out.println(a / b); //進(jìn)行乘法/取模運(yùn)算時(shí)右操作數(shù)不能為0 報(bào) Exception in thread main java.lang.ArithmeticException: / by zero 錯(cuò)誤 System.out.println(a % b); double c a*1.0 / b; //將a進(jìn)行轉(zhuǎn)換/提升為浮點(diǎn)數(shù),之后在參與運(yùn)算,則b也會(huì)進(jìn)行相應(yīng)的提升 System.out.println(c); 5 1 6 1 1 1.0c語(yǔ)言中不允許對(duì)小數(shù)求余數(shù),Java中允許,但是沒(méi)有意義.Java中關(guān)系運(yùn)算符的結(jié)果永遠(yuǎn)都是 boolean類型的值(true,false)c語(yǔ)言中得到的是0/1.int a 10; int b 20; System.out.println(a b); System.out.println(a ! b); System.out.println(a b); System.out.println(a b); false true true falseint a 10; int b 20; int c 30; System.out.println(a b a c ); System.out.println(a b a c); System.out.println(a b || a c); System.out.println(! (a b)); !優(yōu)先級(jí)高于 .計(jì)算機(jī)認(rèn)為先計(jì)算 !a,在和 b進(jìn)行比較. 我們想要的是a和b進(jìn)行比較,然后在進(jìn)行!運(yùn)算所以要加括號(hào) true false true false可以運(yùn)用 , | | 進(jìn)行短路求值.int a 10; int b 20; int c 30; System.out.println(a b a c ); //右邊不會(huì)執(zhí)行 短路求值 System.out.println(a b || a c); //右邊會(huì)執(zhí)行