程式語言教學誌 FB, YouTube: PYDOING: Java 快速導覽

Number 的子類別 (subclass) 有實作如下的方法，可比較另一個 Number 子類別的物件 (object) ，看數值是否相同

方法	描述
int compareTo(Byte anotherByte) int compareTo(Double anotherDouble) int compareTo(Float anotherFloat) int compareTo(Integer anotherInteger) int compareTo(Long anotherLong) int compareTo(Short anotherShort)	比較參數與 Number 物件

舉例如下

class CompareToDemo {
    public static void main(String[] args) {
        Byte a1 = 25;
        Short a2 = 24;
        Integer a3 = 23;
        Long a4 = 22l;
        Float a5 = 21.0f;
        Double a6 = 20.0;
         
        Byte b1 = 25;
        Short b2 = 23;
        Integer b3 = 24;
        Long b4 = 22l;
        Float b5 = 20.0f;
        Double b6 = 20.0;
         
        System.out.println(a1.compareTo(b1));
        System.out.println(a2.compareTo(b2));
        System.out.println(a3.compareTo(b3));
        System.out.println(a4.compareTo(b4));
        System.out.println(a5.compareTo(b5));
        System.out.println(a6.compareTo(b6));
    }
}
 
/* 《程式語言教學誌》的範例程式
    http://pydoing.blogspot.com/
    檔名：CompareToDemo.java
    功能：示範物件導向的基本觀念 
    作者：張凱慶
    時間：西元 2010 年 10 月 */

編譯後執行，結果如下

其中，第 17 行到第 22 行，其為呼叫 compareTo() 方法的地方，這裡，我們直接將回傳的整數印出

System.out.println(a1.compareTo(b1));
System.out.println(a2.compareTo(b2));
System.out.println(a3.compareTo(b3));
System.out.println(a4.compareTo(b4));
System.out.println(a5.compareTo(b5));
System.out.println(a6.compareTo(b6));