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# Java基础：运算符

## 算术运算符

``````package operator;

public class Demo01 {
public static void main(String[] args) {
//二元运算符
//Ctrl + D :复制当前行到下一行
int a = 10;
int b = 20;
int c = 25;
int d = 30;

System.out.println(a+b);
System.out.println(a-b);
System.out.println(a*b);
System.out.println(a/(double)b);
}
}

``````

``````package operator;

public class Demo02 {
public static void main(String[] args) {
long a = 13246422435L;
int b = 123;
short c = 10;
byte d = 8;

System.out.println(a+b+c+d);  //Long
System.out.println(b+c+d);   //Int
System.out.println(b+d);   //Int
}
}

``````

``````package operator;

public class Demo03 {
public static void main(String[] args) {
//关系运算符返回的结果：  正确，错误    布尔值
//if

int a = 10;
int b = 15;
int c = 25;

//取余   模运算
System.out.println(c%a);

System.out.println(a<b);
System.out.println(a>b);
System.out.println(a==b);
System.out.println(a!=b);
}
}

``````

``````package operator;

public class Demo04 {
public static void main(String[] args) {
//++  --    自增，自减  一元运算符
int a = 3;
int b = a++;  //执行完这行代码后，先给b赋值，再自增
//a=a+1;
System.out.println(a);
//a=a+1;
int c = ++a;  //执行完这段代码前，先自增，再给b赋值

System.out.println(a);
System.out.println(b);
System.out.println(c);

//幂运算 2^3   2*2*2=8  很多运算，我们会使用一些工具类来操作！
double pow = Math.pow(2,3);
System.out.println(pow);
}
}

``````

## 逻辑运算符

``````package operator;

//逻辑运算符
public class Demo05 {
public static void main(String[] args) {
//与（and） 或(or)   非(取反)
boolean a = true;
boolean b = false;

System.out.println("a&&b:"+(b&&a)); //逻辑与运算：两个变量都为真，结果才为ture
System.out.println("a||b:"+(b||a)); //逻辑与运算：两个变量有一个为真，则结果才为ture
System.out.println("!(a&&b):"+!(b&&a)); //如果为真，则变为假，如果是假则变为真

//短路运算
int c = 5;
boolean d = (c<4)&&(c++<4);
System.out.println(d);
System.out.println(c);
}
}

``````

## 位运算符

``````package operator;

public class Demo06 {
public static void main(String[] args) {
/*
A = 0011 1100
B = 0101 0110
A&B = 0001 0100
A|B = 0111 1110
A^B = 0110 1010
~B = 1010 1001

2*8 = 16    2*2*2*2
效率极高
<<  *2
>>  /2

0000 0000      0
0000 0001      1
0000 0010      2
0000 0011      3
0000 0100      4
0000 1000      8
0001 0000      16
*/

System.out.println(2<<3);

}
}

``````

## 条件运算符 ？：

``````package operator;

//三元运算符
public class Demo08 {
public static void main(String[] args) {
// x ? y : z
// 如果x=ture,则结果为y，否则结果为z

int score = 50;
String type = score <60 ?"不及格":"及格";  //必须掌握
//if
System.out.println(type);
}
}
``````

## 扩展赋值运算符

``````package operator;

public class Demo07 {
public static void main(String[] args) {
int a = 10;
int b = 20;

a+=b;  //a=a+b
a-=b;  //a=a-b

System.out.println(a);

//字符串连接符  +  ,  String
System.out.println(""+a+b);
System.out.println(a+b+"");
}
}

``````

## Java运算符优先级

``````public class stlye{
public static void main(String[] args){
int a=10,b=6;
System.out.println("改变之前的数：a="+a+",b="+b);
a-=b++;
System.out.println("改变之后的数：a="+a+",b="+b);
}
}
``````