# Java.math.BigInteger.isProbablePrime()方法範例

java.math.BigInteger.isProbablePrime(int certainty) 如果此BigInteger可能是素數，如果其絕對複合返回false。如果確定是≤0，則返回true。

## 宣告

`public boolean isProbablePrime(int certainty)`

## 引數

• certainty - 這一措施的呼叫者能容忍的不確定性：如果呼叫返回true，則此BigInteger是素數超過概率(1 - 1/2確定性)。此方法的執行時間正比於該引數的值。

• NA

## 例子

```package com.yiibai;

import java.math.*;

public class BigIntegerDemo {

public static void main(String[] args) {

// create 3 BigInteger objects
BigInteger bi1, bi2, bi3;

// create 3 Boolean objects
Boolean b1, b2, b3;

// assign values to bi1, bi2
bi1 = new BigInteger("7");
bi2 = new BigInteger("9");

// perform isProbablePrime on bi1, bi2
b1 = bi1.isProbablePrime(1);
b2 = bi2.isProbablePrime(1);
b3 = bi2.isProbablePrime(-1);

String str1 = bi1+ " is prime with certainity 1 is " +b1;
String str2 = bi2+ " is prime with certainity 1 is " +b2;
String str3 = bi2+ " is prime with certainity -1 is " +b3;

// print b1, b2, b3 values
System.out.println( str1 );
System.out.println( str2 );
System.out.println( str3 );
}
}```

```7 is prime with certainity 1 is true
9 is prime with certainity 1 is false
9 is prime with certainity -1 is true```