Java Number类

一般情况下我们会使用数据的基本数据类型：byte、int、short、long、double、float、boolean、char；
对应的包装类型也有八种：Byte、Integer、Short、Long、Double、Float、Character、Boolean;
包装类型都是用final声明了，不可以被继承重写；

 public static void main(String[] args) {
        int num1 = 1;
        //将基本数据类型装箱成对象包装类型
        Integer num2 = num1;

        Integer num3 = 3;
        //将对象数据类拆箱
        int num4 = num3;
    }

//Long
public final class Long extends Number implements Comparable<Long> 

//Integer
public final class Integer extends Number implements Comparable<Integer> 

//Short
public final class Short extends Number implements Comparable<Short> 

//Byte
public final class Byte extends Number implements Comparable<Byte>

//Double

public final class Double extends Number implements Comparable<Double>

//Float
public final class Float extends Number implements Comparable<Float>

//Charater
public final
class Character implements java.io.Serializable,Comparable<Character>

//Boolean
public final class Boolean implements java.io.Serializable,Comparable<Boolean>

package java.lang;

public abstract class Number implements java.io.Serializable {

    public abstract int intValue();

    public abstract long longValue();

    public abstract float floatValue();

    public abstract double doubleValue();

    public byte byteValue() {
        return (byte)intValue();
    }

    public short shortValue() {
        return (short)intValue();
    }

    private static final long serialVersionUID = -8742448824652078965L;
}