运算符是一种特殊的符号，表示数据的运算、赋值和比较
算术运算、赋值运算、比较运算、逻辑运算、位运算（开发用的少，源码中有存在）、三元运算
| 运算符 | 运算 | 类别 | 结果 |
| + | 正 | +3 | 3 |
| - | 负 | b=4；-b | -4 |
| + | 加 | 5+5 | 10 |
| - | 减 | 6-4 | 2 |
| * | 乘 | 3*4 | 12 |
| / | 除 | 5/5 | 1 |
| % | 取模（取余数） | 7%5 | 2 |
| ++ | 前加加自增在前，先运算后取值 | a=2;b=++a | a=3;b=3 |
| ++ | 后加加自增在后，先取值后运算 | a=2;b=a++ | a=3;b=2 |
| -- | 前减减自减在前，先运算后取值 | a=2;b=--a | a=1;b=1 |
| -- | 后减减自减在后，先取值后运算 | a=2;b=a-- | a=1;b=2 |
| + | 字符连接运算 | "He"+"llo" | "Hello" |
加减乘除的示例
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
}
}
编译后运行
---------- java ----------
2
7
60
17
输出完成 (耗时 0 秒) - 正常终止
示例2，使计算过为浮点型
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
}
}
---------- java ----------
2
7
60
17
2.4
输出完成 (耗时 0 秒) - 正常终止
取模
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
}
}
---------- java ----------
2
7
60
17
2.4
2
输出完成 (耗时 0 秒) - 正常终止
前加加；后加加
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
int a1 = 10;
int b1 = ++a1;// 前加加，先运算后赋值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 后加加，先赋值后运算
System.out.println(b2 +"," + a2);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
输出完成 (耗时 0 秒) - 正常终止
注意点
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
int a1 = 10;
int b1 = ++a1;// 前加加，先运算后赋值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 后加加，先赋值后运算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
s1 = s1+1;// 编译不过
System.out.println(s1);
}
}
---------- javac ----------
AriTest.java:27: 错误: 不兼容的类型: 从int转换到short可能会有损失
s1 = s1+1;// 编译不过
^
1 个错误
输出完成 (耗时 0 秒) - 正常终止
建议一下两种方式
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
int a1 = 10;
int b1 = ++a1;// 前加加，先运算后赋值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 后加加，先赋值后运算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 编译不过
s1 = (short)(s1+1);
System.out.println(s1);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
11
输出完成 (耗时 0 秒) - 正常终止
或者
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
int a1 = 10;
int b1 = ++a1;// 前加加，先运算后赋值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 后加加，先赋值后运算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 编译不过
//s1 = (short)(s1+1);
++s1;//
System.out.println(s1);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
11
输出完成 (耗时 0 秒) - 正常终止
或者
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
int a1 = 10;
int b1 = ++a1;// 前加加，先运算后赋值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 后加加，先赋值后运算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 编译不过
//s1 = (short)(s1+1);
s1++;// 这样写不会改变他的数据类型
System.out.println(s1);
}
}
前减减；后减减
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法运算
System.out.println(result1);
int result2 = num1 - num2; //减法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
double result5 = (double)num1 / num2; //浮点型结果为2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
int a1 = 10;
int b1 = ++a1;// 前加加，先运算后赋值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 后加加，先赋值后运算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 编译不过
//s1 = (short)(s1+1);
s1++;// 这样写不会改变他的数据类型
System.out.println(s1);
int s2 = 15;
int s3 = --s2;
System.out.println(s3);
int s4 = 15;
int s5 = s4--;
System.out.println(s5);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
11
14
15
输出完成 (耗时 0 秒) - 正常终止