java 运算符

 

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