java例程练习（基础数据类型的包装类）

public class Test {
public static void main(String[] args) {
Integer i = new Integer(100);
Double d = new Double("123.456");

int j = i.intValue() + d.intValue();
float f = i.floatValue() + d.floatValue();
System.out.println(j);
System.out.println(f);

double pi = Double.parseDouble("3.1415926");
double r = Double.valueOf("2.0").doubleValue();
double s = pi * r * r;
System.out.println(s);

try {
int k = Integer.parseInt("1.23");
System.out.println(k);
} catch (NumberFormatException e) {
System.out.println("格式不正确");
}

System.out.println(Integer.toBinaryString(123) + "B");
System.out.println(Integer.toHexString(123) + "H");
System.out.println(Integer.toOctalString(123) + "O");
}
}