java 運算子
阿新 • • 發佈：2020-07-18
運算子是一種特殊的符號，表示資料的運算、賦值和比較
算術運算、賦值運算、比較運算、邏輯運算、位運算（開發用的少，原始碼中有存在）、三元運算
| 運算子 | 運算 | 類別 | 結果 |
| + | 正 | +3 | 3 |
| - | 負 | b=4；-b | -4 |
| + | 加 | 5+5 | 10 |
| - | 減 | 6-4 | 2 |
| * | 乘 | 3*4 | 12 |
| / | 除 | 5/5 | 1 |
| % | 取模（取餘數） | 7%5 | 2 |
| ++ | 前加加自增在前，先運算後取值 | a=2;b=++a | a=3;b=3 |
| ++ | 後加加自增在後，先取值後運算 | a=2;b=a++ | a=3;b=2 |
| -- | 前減減自減在前，先運算後取值 | a=2;b=--a | a=1;b=1 |
| -- | 後減減自減在後，先取值後運算 | a=2;b=a-- | a=1;b=2 |
| + | 字元連線運算 | "He"+"llo" | "Hello" |
加減乘除的示例
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
System.out.println(result2);
int result3 = num1 * num2 ; //乘
System.out.println(result3);
int result4 = num1 + num2; // 加
System.out.println(result4);
}
}
編譯後執行
---------- java ----------
2
7
60
17
輸出完成 (耗時 0 秒) - 正常終止
示例2，使計算過為浮點型
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為2.41
System.out.println (result5);
}
}
---------- java ----------
2
7
60
17
2.4
輸出完成 (耗時 0 秒) - 正常終止
取模
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為2.41
System.out.println (result5);
int result6 = num1 % num2; // 取模
System.out.println (result6);
}
}
---------- java ----------
2
7
60
17
2.4
2
輸出完成 (耗時 0 秒) - 正常終止
前加加；後加加
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為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，先運算後賦值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 後加加，先賦值後運算
System.out.println(b2 +"," + a2);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
輸出完成 (耗時 0 秒) - 正常終止
注意點
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為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，先運算後賦值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 後加加，先賦值後運算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
s1 = s1+1;// 編譯不過
System.out.println(s1);
}
}
---------- javac ----------
AriTest.java:27: 錯誤: 不相容的型別: 從int轉換到short可能會有損失
s1 = s1+1;// 編譯不過
^
1 個錯誤
輸出完成 (耗時 0 秒) - 正常終止
建議一下兩種方式
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為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，先運算後賦值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 後加加，先賦值後運算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 編譯不過
s1 = (short)(s1+1);
System.out.println(s1);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
11
輸出完成 (耗時 0 秒) - 正常終止
或者
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為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，先運算後賦值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 後加加，先賦值後運算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 編譯不過
//s1 = (short)(s1+1);
++s1;//
System.out.println(s1);
}
}
---------- java ----------
2
7
60
17
2.4
2
11,11
10,11
11
輸出完成 (耗時 0 秒) - 正常終止
或者
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為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，先運算後賦值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 後加加，先賦值後運算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 編譯不過
//s1 = (short)(s1+1);
s1++;// 這樣寫不會改變他的資料型別
System.out.println(s1);
}
}
前減減；後減減
class AriTest
{
public static void main(String[] args)
{
int num1 = 12;
int num2 = 5;
int result1 = num1 / num2; //除法運算
System.out.println(result1);
int result2 = num1 - num2; //減法
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; //浮點型結果為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，先運算後賦值
System.out.println(b1+","+a1);
int a2 = 10;
int b2 = a2++;// 後加加，先賦值後運算
System.out.println(b2 +"," + a2);
//注意
short s1 = 10;
//s1 = s1+1;// 編譯不過
//s1 = (short)(s1+1);
s1++;// 這樣寫不會改變他的資料型別
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
輸出完成 (耗時 0 秒) - 正常終止