class WaterSource {
private String s;
WaterSource() {
System.out.println("WaterSource()");
s = new String("Constructed");
}
public String toString() { return s; }
}public class SprinklerSystem { private String valve1, valve2, valve3, valve4;
private WaterSource source;
private int i;
private float f;
public String toString() {
return
"valve1 = " + valve1 + "\n" +
"valve2 = " + valve2 + "\n" +
"valve3 = " + valve3 + "\n" +
"valve4 = " + valve4 + "\n" +
"i = " + i + "\n" +
"f = " + f + "\n" +
"source = " + source;
}
public static void main(String[] args) { SprinklerSystem sprinklers = new SprinklerSystem(); System.out.println(sprinklers);
}
} 请帮我解释一下 System.out.println(sprinklers);为什么会打出valve1 = null
valve2 = null",
valve3 = null",
valve4 = null",
i = 0
f = 0.0",
source = null"
这些呢?
而下是sprinklers@address
toString方法我并没有主主动去调用啊
请大家帮帮我
private String s;
WaterSource() {
System.out.println("WaterSource()");
s = new String("Constructed");
}
public String toString() { return s; }
}public class SprinklerSystem { private String valve1, valve2, valve3, valve4;
private WaterSource source;
private int i;
private float f;
public String toString() {
return
"valve1 = " + valve1 + "\n" +
"valve2 = " + valve2 + "\n" +
"valve3 = " + valve3 + "\n" +
"valve4 = " + valve4 + "\n" +
"i = " + i + "\n" +
"f = " + f + "\n" +
"source = " + source;
}
public static void main(String[] args) { SprinklerSystem sprinklers = new SprinklerSystem(); System.out.println(sprinklers);
}
} 请帮我解释一下 System.out.println(sprinklers);为什么会打出valve1 = null
valve2 = null",
valve3 = null",
valve4 = null",
i = 0
f = 0.0",
source = null"
这些呢?
而下是sprinklers@address
toString方法我并没有主主动去调用啊
请大家帮帮我
System.out.println(obj) --> PrintStream.println(obj), println(obj)--> String.ValueOf(obj) 再看看String.ValueOf(obj)的说明。
System.out.println(obj) --> PrintStream.println(obj), println(obj)--> String.ValueOf(obj)再看看String.ValueOf(obj)的说明。