java 如何使用扫描仪从用户那里获取Hashmap的输入
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How to get input from user for Hashmap using Scanner
提问by Sainath Pawar
How to get input from user for Hashmap using scanner and print the respective hashmap
如何使用扫描仪从用户那里获取哈希图的输入并打印相应的哈希图
import java.util.HashMap;
public class Map {
public static void main(String[] args) {
// TODO Auto-generated method stub
HashMap <Integer,Integer> hmap = new HashMap<Integer,Integer>();
Scanner in = new Scanner(System.in);
for(int i=0;i<3;i++){
Integer a=in.nextInt();
Integer b=in.nextInt();
hmap.put(a, b);
System.out.println(hmap.put(a,b));
}
}
}
I am not getting the desired output. I want to print what is inserted in hmap.
我没有得到所需的输出。我想打印插入的内容hmap。
回答by ProgrammerBoy
Change your System.out.printlnstatement to,
将您的System.out.println声明更改为，
System.out.println(hmap.get(a));
回答by Saideep Sambaraju
What do you expect this to do? It is wrong, why would you print hmap.put(a,b)
你希望这能做什么？错了，为什么要打印hmap.put(a,b)
System.out.println(hmap.put(a,b));
Just take it out of the for loop and print it separately
只需将其从for循环中取出并单独打印即可
for (Map.Entry<Integer, Integer> pair: hmap.entrySet()) {
System.out.println(pair.getKey() + "->" + pair.getValue());
}
回答by JosephCW
Javadoc for the HashMap util can be found here.
可以在此处找到 HashMap 实用程序的 Javadoc 。
To add a key/value pair to a HashMap you use hashmap.put(x, y).
要将键/值对添加到 HashMap，您可以使用hashmap.put(x, y).
Using hashmap.get(x)at a later time will return y.
使用hashmap.get(x)在稍后的时间将返回年。
Edit: It looks like from other comments you are trying to have it print out both the key and the value. In the case that you are trying to print out all keys and values something like this may work.
编辑：从其他评论看来，您试图让它打印出键和值。在您尝试打印出所有键和值的情况下，这样的事情可能会奏效。
hashMap.forEach((e, k) -> {
System.out.println("E: " + e + " K: " + k);
})
If this is not your intended purpose I would strongly recommend reading over the method summary section of the javadocs.
如果这不是您的预期目的，我强烈建议您阅读 javadocs 的方法摘要部分。
回答by Kaustav Pallob
This is another way by which we can insert data in Hashmapin Run time:
这是我们可以Hashmap在运行时插入数据的另一种方式：
import java.util.*;
public class Maap {
public static void main(String[] args) {
HashMap <Integer,String> hmap = new HashMap<Integer,String>();
Scanner in = new Scanner(System.in);
for(int i=0;i<3;i++){
Integer a=in.nextInt();
String b=in.next();
hmap.put(a,b);
// System.out.println(hmap.get(b)+" "+hmap.get(a));
}
for(Map.Entry m:hmap.entrySet()) {
System.out.println(m.getKey()+" "+m.getValue());
}
}
}
