//初始化
public BigInteger(String val)
public BigInteger(byte[] val)
public static BigInteger valueOf(long val)
//四則運(yùn)算
public BigInteger add(BigInteger val)  //加法
public BigInteger subtract(BigInteger val)  //減法
public BigInteger multiply(BigInteger val)  //乘法
public BigInteger divide(BigInteger val)  //除法（整除）
//取余（取模）
public BigInteger mod(BigInteger m)
public BigInteger remainder(BigInteger val)  
//其他基本運(yùn)算
public BigInteger negate()  //取反
public BigInteger abs()  //絕對(duì)值
public BigInteger pow(int exponent)  //指數(shù)
public BigInteger max(BigInteger val)  //較大者
public BigInteger min(BigInteger val)  //較小者
public BigInteger gcd(BigInteger val)  //最大公約數(shù)
//判斷與比較
public int compareTo(BigInteger val)  //比較大小
public boolean equals(Object x)  //判斷是否相等
//十進(jìn)制轉(zhuǎn)換為其他進(jìn)制
public byte[] toByteArray()  //轉(zhuǎn)換為二進(jìn)制數(shù)組
public String toString(int radix)  //轉(zhuǎn)換為 radix 進(jìn)制數(shù)，2<=radix<=36，否則令radix=10
//其他進(jìn)制轉(zhuǎn)換為十進(jìn)制
public BigInteger(String val, int radix)  //將 radix 進(jìn)制的val轉(zhuǎn)換為十進(jìn)制，2<=radix<=36，否則拋出NumberFormatException異常

public static String toBinaryString(int i)  將i轉(zhuǎn)換為2進(jìn)制
public static String toOctalString(int i)  將i轉(zhuǎn)換為8進(jìn)制
public static String toHexString(int i)  將i轉(zhuǎn)換為16進(jìn)制
public static String toString(int i, int radix)  將i轉(zhuǎn)換為 radix 進(jìn)制，2<=radis<=36，否則令radis=10

//將 radix 進(jìn)制數(shù)s轉(zhuǎn)換為十進(jìn)制，2<=radix<=36，否則拋出NumberFormatException異常
public static int parseInt(String s, int radix) throws NumberFormatException
public static Integer valueOf(String s, int radix) throws NumberFormatException

//將 m 進(jìn)制數(shù)轉(zhuǎn)換為 n 進(jìn)制數(shù)
public static String transform(String s_m,int m,int n) {
    Integer tem=Integer.parseInt(s_m,m); //將m進(jìn)制的s_m轉(zhuǎn)換為10進(jìn)制
    String s_n=Integer.toString(tem,n); //將tem轉(zhuǎn)換為n進(jìn)制
    return s_n;
}