JAVA基础--toString, equals方法

public class TestEquals {
public static void main(String[] args) {
Cat c1 = new Cat(1, 2, 3);
Cat c2 = new Cat(1, 2, 3);
System.out.println(c1 == c2);
System.out.println(c1.equals(c2));String s1 = new String("hello");
String s2 = new String("hello");
System.out.println(s1 == s2);
System.out.println(s1.equals(s2));
}
}class Cat {
int color;
int height, weight;public Cat(int color, int height, int weight) {
this.color = color;
this.height = height;
this.weight = weight;
}public boolean equals(Object obj) {
if(obj == null) return false;
else {
if(obj instanceof Cat) {
Cat c = (Cat)obj;
if(c.color == this.color && c.height == this.height && c.weight == this.weight) {
return true;
}
}
}return false;
}}

--------------------Configuration: <Default>--------------------
false
true
false
true

public class TestToString {
public static void main(String[] args) {
Dog d = new Dog();
System.out.println("d:=" + d);
}
}class Dog {
public String toString() {
return "I'm a cool dog!";
}
}