Java 類中toString 及類的組合
阿新 • • 發佈:2018-10-31
class WaterSource{ private String s; WaterSource(){ System.out.println("WaterSource()"); s="Contructed"; } public String toString(){return s;} } public class SprinklerSystem { private String value1,value2,value3,value4; private WaterSource source=new WaterSource(); private int i; private float f; public String toString(){ return "value1 = "+value1+" "+ "value2 = "+value2+" "+ "value3 = "+value3+" "+ "value4 = "+value4+"\n "+ "i = "+i+" "+"f = "+f+" "+ "source = "+source; } public static void main(String[] args){ SprinklerSystem sprinker=new SprinklerSystem(); System.out.println(sprinker); } } /* * 在上面兩個類所定義的方法中,有一個很特殊:toString().每個非基本型別的物件都有一個toString()方法,而且當編譯器 * 需要一個String而你只有一個物件時,該方法就會被呼叫。 */
輸出:
WaterSource()
value1 = null value2 = null value3 = null value4 = null
i = 0 f = 0.0 source = Contructed