Java 类中toString 及类的组合，javatostring

Java 类中toString 及类的组合，javatostring

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);
}
}
/*
 * 在上面两个类所定义的方法中，有一个很特殊：toString().每个非基本类型的对象都有一个toString()方法，而且当编译器
 * 需要一个String而你只有一个对象时，该方法就会被调用。
 */

输出：

WaterSource()
value1 = null value2 = null value3 = null value4 = null
 i = 0 f = 0.0 source = Contructed