Java基础编程_2.Java基本语法（中）

 1         //除号：/
 2         int num1 = 12;  3         int num2 = 5;  4         int result1 = num1 / num2;  5         System.out.println(result1);//2  6         // %:取余运算  7         //结果的符号与被模数的符号相同  8         //开发中，经常使用%来判断能否被除尽的情况。
 9         int m1 = 12; 10         int n1 = 5; 11         System.out.println("m1 % n1 = " + m1 % n1); 12 
13         int m2 = -12; 14         int n2 = 5; 15         System.out.println("m2 % n2 = " + m2 % n2); 16 
17         int m3 = 12; 18         int n3 = -5; 19         System.out.println("m3 % n3 = " + m3 % n3); 20 
21         int m4 = -12; 22         int n4 = -5; 23         System.out.println("m4 % n4 = " + m4 % n4); 24         //(前)++ :先自增1，后运算 25         //(后)++ :先运算，后自增1
26         int a1 = 10; 27         int b1 = ++a1; 28         System.out.println("a1 = " + a1 + ",b1 = " + b1); 29         
30         int a2 = 10; 31         int b2 = a2++; 32         System.out.println("a2 = " + a2 + ",b2 = " + b2); 33         
34         int a3 = 10; 35         ++a3;//a3++;
36         int b3 = a3; 37         //(前)-- :先自减1，后运算 38         //(后)-- :先运算，后自减1
39         
40         int a4 = 10; 41         int b4 = a4--;//int b4 = --a4;
42         System.out.println("a4 = " + a4 + ",b4 = " + b4);

 1         int i2,j2;  2         //连续赋值
 3         i2 = j2 = 10;  4         //***************
 5         int i3 = 10,j3 = 20;  6         int num1 = 10;  7         num1 += 2;//num1 = num1 + 2;
 8         System.out.println(num1);//12
 9 
10         int num2 = 12; 11         num2 %= 5;//num2 = num2 % 5;
12  System.out.println(num2); 13 
14         short s1 = 10; 15         //s1 = s1 + 2;//编译失败
16         s1 += 2;//结论：不会改变变量本身的数据类型
17         System.out.println(s1);

 1         int i = 10;  2         int j = 20;  3 
 4         System.out.println(i == j);//false
 5         System.out.println(i = j);//20
 6 
 7         boolean b1 = true;  8         boolean b2 = false;  9         System.out.println(b2 == b1);//false
10         System.out.println(b2 = b1);//true

 1 //区分& 与 &&  2 //相同点1：& 与 && 的运算结果相同  3 //相同点2：当符号左边是true时，二者都会执行符号右边的运算  4 //不同点：当符号左边是false时，&继续执行符号右边的运算。&&不再执行符号右边的运算。  5 //开发中，推荐使用&&
 6 boolean b1 = true;  7 b1 = false;  8 int num1 = 10;  9 if(b1 & (num1++ > 0)){ 10 　　System.out.println("我现在在北京"); 11 }else{ 12 　　System.out.println("我现在在南京"); 13 } 14 
15 System.out.println("num1 = " + num1); 16 boolean b2 = true; 17 b2 = false; 18 int num2 = 10; 19 if(b2 && (num2++ > 0)){ 20 　　System.out.println("我现在在北京"); 21 }else{ 22 　　System.out.println("我现在在南京"); 23 } 24 
25 System.out.println("num2 = " + num2); 26 
27 // 区分：| 与 || 28 //相同点1：| 与 || 的运算结果相同 29 //相同点2：当符号左边是false时，二者都会执行符号右边的运算 30 //不同点3：当符号左边是true时，|继续执行符号右边的运算，而||不再执行符号右边的运算 31 //开发中，推荐使用||
32 boolean b3 = false; 33 b3 = true; 34 int num3 = 10; 35 if(b3 | (num3++ > 0)){ 36 　　System.out.println("我现在在北京"); 37 }else{ 38 　　System.out.println("我现在在南京"); 39 } 40 System.out.println("num3 = " + num3); 41 
42 
43 boolean b4 = false; 44 b4 = true; 45 int num4 = 10; 46 if(b4 || (num4++ > 0)){ 47 　　System.out.println("我现在在北京"); 48 }else{ 49 　　System.out.println("我现在在南京"); 50 } 51 System.out.println("num4 = " + num4);

 1         int i = 21;  2         i = -21;  3         System.out.println("i << 2 :" + (i << 2));  4         System.out.println("i << 3 :" + (i << 3));  5         System.out.println("i << 27 :" + (i << 27));  6 
 7         int m = 12;  8         int n = 5;  9         System.out.println("m & n :" + (m & n)); 10         System.out.println("m | n :" + (m | n)); 11         System.out.println("m ^ n :" + (m ^ n));