java常用库学习（3）

package excise;

import java.text.NumberFormat;

public class NumberFormatDemo {
public static void main(String args[]){
NumberFormat nf=NumberFormat.getInstance();
System.out.println("格式化之后的数字是 ："+nf.format(10000000));
System.out.println("格式化之后的数字是 ："+nf.format(1000.345));
}

}

package excise;

import java.text.DecimalFormat;
public class <span style="font-family: Arial, Helvetica, sans-serif;">DecimalFormat</span><span style="font-family: Arial, Helvetica, sans-serif;">Demo {</span>
public void format1(String pattern,double value){
DecimalFormat   df=new DecimalFormat();
String str=df.format(value);
System.out.println("使用"+pattern+"格式化数字"+value+":  "+str);
}
public static void main(String args[]){
NumberFormatDemo demo=new NumberFormatDemo();
demo.format1("###,###.###", 111222.3456);

}

}

package excise;
import java.math.BigInteger;
public class BigIntergerDemo{
public static void main(String args[]){
BigInteger   bil=new BigInteger("123456789");
BigInteger  bi2=new BigInteger("987654321");
System.out.println("加法操作"+bil.add(bi2));
System.out.println("减法操作"+bil.subtract(bi2));
System.out.println("乘法操作"+bil.multiply(bi2));
System.out.println("除法操作"+bil.divide(bi2));

}

}