Java-运算符

1.基本运算符
+：加法运算
- ：减法
* ：乘法
/ ：除法
%：取模
++：自加运算
–：自减运算
+=：加法赋值
-=：减法赋值
*=：乘法赋值
/=：除法赋值

    public class TestJava {    public static void main(String[] args){        //声明两个int类型的变量        int i1 = 7;        int i2 = 2;        System.out.println("基本元素符：整数类型");        System.out.println("i1="+i1+"  "+"i2="+i2);        System.out.println("i1+i2="+(i1+i2));        System.out.println("i1+i2="+(i1-i2));        System.out.println("i1+i2="+(i1*i2));        System.out.println("i1+i2="+((double)i1/i2));        //声明两个double类型的变量        double d1 = 8.0;        double d2 = 2.5;        System.out.println("基本元素符：浮点类型");        System.out.println("d1="+d1+"  "+"d2="+d2);        System.out.println("d1+d2="+(d1+d2));        System.out.println("d1+d2="+(d1-d2));        System.out.println("d1+d2="+(d1*d2));        System.out.println("d1+d2="+((double)d1/d2));    }}

2.模运算符
%：是求两个整数相除的余数
取模运算不建议用于浮点类型，结果可能不准确
对于精度高的运算，需要使用BigDecimal类型

public class TestJava {    public static void main(String[] args){        int i1 = 5;        int i2 = 2;        double d1 = 2.4;        double d2 = 1.1;        System.out.println("i1="+i1+"  "+"i2="+i2);             System.out.println("d1="+d1+"  "+"d2="+d2);             System.out.println("i1%i2="+(i1%i2));               System.out.println("i1%d1="+(i1%d1));        System.out.println("d1%d2="+(d1%d2));           System.out.println("d1%i2="+(d1%i2));           }}/**    输出结果i1=5  i2=2d1=2.4  d2=1.1i1%i2=1i1%d1=0.20000000000000018d1%d2=0.19999999999999973d1%i2=0.3999999999999999*/

3.算术赋值运算符
i = i+5； –> i+=5;

        int i1 = 1;        int i2 = 3;        int i3 = 5;        int i4 = 7;        int i5 = 9;        //对于这些变量进行运算赋值运算        i1+=2;        i2-=2;        i3*=2;        i4/=2;        i5%=2;        //i1 = 1+2在赋值给i1        System.out.println(i1+","+i2+","+i3+","+i4+","+i5);

4.自增自减运算符
i=i+1; i+=1; i++
i=i-1; i-=1; i–

++i 先加在用
i++ 先用在加，先用完本身的值，再加

public class TestJava {    public static void main(String[] args){        int i = 5;        System.out.println("i="+i);        System.out.println("++i="+(++i));        System.out.println("i="+i);        System.out.println("i++="+(i++));        System.out.println("i="+i);    }}

5.关系运算符
返回值是boolean 一般用于判断语句当中
==、 ！=、 > 、 <、 >= 、<=

public class TestJava {    public static void main(String[] args){        int a = 3;        int b = 5;        boolean b1,b2,b3,b4;        b1 = a == b;        b2 = a !=b;        b3 = a > b;        b4 = a < b;        System.out.println(b1+","+b2+","+b3+","+b4);    }}

6.逻辑运算符
&：逻辑与 、|：逻辑或 、！：逻辑非运算
&&：短路与 、||：短路或

与 运算符：所有条件都为真，则结果才为真，只要有一个假，结果就是假
或 运算符：只要有一个为真，结果就是真，所有条件都是假 结果才为假
boolean b;
b = condition1 &condition2;//先求得1,2的值，然后进行判断
b = condition1 &&condition2;//首先对condition1进行判断，如果为真在判断condition2，如果condition1为假，则不对condition2进行判断

public class TestJava {    public static boolean returntrue(){        System.out.println("return true");        return true;    }    public static boolean returnfalse(){        System.out.println("return false");        return false;    }    public static void main(String[] args){        boolean b1;        System.out.println("逻辑与运算 returntrue()&returnfalse");        b1 = returntrue()&returnfalse();        System.out.println(b1);        System.out.println("短路与运算 returntrue()&&returnfalse");        boolean b2 = returntrue()&&returnfalse();        System.out.println(b2);        System.out.println("逻辑或运算 returntrue()|returnfalse");        boolean b3 = returntrue()|returnfalse();        System.out.println(b3);        System.out.println("短路或运算 returntrue()||returnfalse");        boolean b4 = returntrue()&&returnfalse();        System.out.println(b4);    }}

7.三元运算符

public class TestJava {    public static void main(String[] args) {        int i,k,j;        i = 4;        j = 5;        /**        k = i >= j?i:j;        如果k = i 大于等于j        ？比较         i:j 如果i>=j输出i        否则输出j        */        k = i >= j?i:j;        System.out.println(k);    }}

8.运算符优先级
()优先运算里边的内容
i= (k++);