我如何在arraylist“list”中打印元素“e”？
@H_502_2@ArrayList<Dog> list = new ArrayList<Dog>();
Dog e = new Dog();
list.add(e);
System.out.println(list);
解决方法
要打印整个列表还是要遍历列表的每个元素？无论哪种方式打印任何有意义的Dog类需要从Object类覆盖toString()方法(如其他答案中所述),以返回有效的结果.
@H_502_2@public class Print {
public static void main(final String[] args) {
List<Dog> list = new ArrayList<Dog>();
Dog e = new Dog("Tommy");
list.add(e);
list.add(new Dog("tiger"));
System.out.println(list);
for(Dog d:list) {
System.out.println(d);
// prints [Tommy,tiger]
}
}
private static class Dog {
private final String name;
public Dog(final String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}
}
@H_502_2@[Tommy,tiger]
Tommy
tiger
