Java 番石榴| IntMath log10(int x，RoundingMode 模式)方法带示例
原文:https://www . geesforgeks . org/Java-guava-int math-log 10 int-x-rounding mode-method-with-examples/
番石榴 IntMath Class 的 log10(int x，rounding mode)方法接受两个参数，并根据第二个参数指定的舍入方式计算第一个参数舍入后的基数-10 对数值。
语法:
public static int log10(int x, RoundingMode mode)
参数:该方法取 2 个参数:
- x is the int value log to be searched.
- mode is the specified rounding mode.
返回值:该方法返回 x 的以 10 为底的对数，根据指定的舍入方式进行舍入。
异常:此方法抛出以下参数:
- 非法辩解例外:x < 0′I′I′I′I′I′I。
- Arithmetic exception: If the mode is circular mode. No need, x is not a power of ten.
枚举舍入模式
| 枚举常数 | 描述 |
|---|---|
| 【天花板】 | 舍入模式向正无穷大舍入。 |
| DOWN | 舍入模式为向零舍入。 |
| FLOOR | 舍入模式为向负无穷大舍入。 |
| HALF _ DOWN | 舍入模式为向“最近邻居”舍入，除非两个邻居等距，在这种情况下舍入为 DOWN。 |
| HALF _ EVEN | 舍入模式为向“最近邻居”舍入，除非两个邻居等距，在这种情况下，向偶数邻居舍入。 |
| 【HALF _ UP】 | 取整模式为向“最近邻居”取整，除非两个邻居等距，在这种情况下取整。 |
| 【不必要的】 | 舍入模式断言请求的操作有确切的结果，因此没有舍入的必要。 |
| UP | 取整模式为远离零取整。 |
下面给出了一些例子，以便更好地理解实现:
例 1 :
// Java code to show implementation of
// log10(int x, RoundingMode mode) method
// of Guava's IntMath class
import java.math.RoundingMode;
import com.google.common.math.IntMath;
class GFG {
// Driver code
public static void main(String args[])
{
int a1 = 10000;
// Using log10(int x, RoundingMode mode)
// method of Guava's IntMath class
// The RoundingMode HALF_EVEN rounds towards
// the "nearest neighbor" unless both neighbors
// are equidistant, in which case, round towards
// the even neighbor.
System.out.println(
IntMath.log10(a1,
RoundingMode.HALF_EVEN));
int a2 = 15;
// Using log10(int x, RoundingMode mode)
// method of Guava's IntMath class
// The RoundingMode HALF_DOWN rounds towards
// "nearest neighbor" unless both neighbors
// are equidistant, in which case round down.
System.out.println(
IntMath.log10(a2,
RoundingMode.HALF_DOWN));
}
}
输出:
4
1
例 2 :
// Java code to show implementation of
// log10(int x, RoundingMode mode) method
// of Guava's IntMath class
import java.math.RoundingMode;
import com.google.common.math.IntMath;
class GFG {
static int findlog10(int x, RoundingMode mode)
{
try {
// Using log10(int x, RoundingMode mode)
// method of Guava's IntMath class
// The RoundingMode HALF_EVEN rounds towards
// the "nearest neighbor" unless both neighbors
// are equidistant, in which case, round towards
// the even neighbor.
// This should throw "IllegalArgumentException"
// as x <= 0
int ans = IntMath.log10(x, mode);
// Return the answer
return ans;
}
catch (Exception e) {
System.out.println(e);
return -1;
}
}
// Driver code
public static void main(String args[])
{
int x = -152;
try {
// Function calling
findlog10(x, RoundingMode.HALF_EVEN);
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
java.lang.IllegalArgumentException: x (-152) must be > 0
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