我试图打印出一个列表的所有元素,但它是打印对象的指针,而不是值。
这是我的打印代码…
for(int i=0;i<list.size();i++){
System.out.println(list.get(i));
}
有人能告诉我为什么它不打印元素的值吗?
我试图打印出一个列表的所有元素,但它是打印对象的指针,而不是值。
这是我的打印代码…
for(int i=0;i<list.size();i++){
System.out.println(list.get(i));
}
有人能告诉我为什么它不打印元素的值吗?
当前回答
For循环输出列表的内容:
List<String> myList = new ArrayList<String>();
myList.add("AA");
myList.add("BB");
for ( String elem : myList ) {
System.out.println("Element : "+elem);
}
结果:
Element : AA
Element : BB
如果你想打印在单行(只是为了信息):
String strList = String.join(", ", myList);
System.out.println("Elements : "+strList);
结果:
Elements : AA, BB
其他回答
使用String.join () 例如:
System.out.print(String.join("\n", list));
尝试重写toString()方法,因为您希望元素将被打印。 打印的方法可以是这样的:
for(int i=0;i<list.size();i++){
System.out.println(list.get(i).toString());
}
下面是一些关于打印list组件的例子:
public class ListExample {
public static void main(String[] args) {
List<Model> models = new ArrayList<>();
// TODO: First create your model and add to models ArrayList, to prevent NullPointerException for trying this example
// Print the name from the list....
for(Model model : models) {
System.out.println(model.getName());
}
// Or like this...
for(int i = 0; i < models.size(); i++) {
System.out.println(models.get(i).getName());
}
}
}
class Model {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
You haven't specified what kind of elements the list contains, if it is a primitive data type then you can print out the elements. But if the elements are objects then as Kshitij Mehta mentioned you need to implement (override) the method "toString" within that object - if it is not already implemented - and let it return something meaning full from within the object, example: class Person { private String firstName; private String lastName; @Override public String toString() { return this.firstName + " " + this.lastName; } }
public static void main(String[] args) {
answer(10,60);
}
public static void answer(int m,int k){
AtomicInteger n = new AtomicInteger(m);
Stream<Integer> stream = Stream.generate(() -> n.incrementAndGet()).limit(k);
System.out.println(Arrays.toString(stream.toArray()));
}