java.lang.Number解读

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;
}