[英]How to take user input multiple times and store it in the same array list?
[英]How to output an element that has occured or listed multiple times in an array list from a user input
在不使用 collections、hashmap 或樹圖方法的情況下,如何 output 用戶輸入多次重復的元素(索引內容)?
我正在尋找線性方法,或者您可以說數學方法而不是現成的命令方法,有人可以幫忙嗎?
import java.util.ArrayList;
import java.util.Scanner;
Scanner scanner = new Scanner(System.in);
ArrayList<Integer> arrayList = new ArrayList<>();
while (true) {
int input = scanner.nextInt();
if (input == -1) {
break;
}
arrayList.add(input);
}
System.out.println("search for? ");
for (int loopValue = 0; loopValue < arrayList.size(); loopValue++) {
int input2 = scanner.nextInt();
System.out.println(input2 + " is at index " + arrayList.indexOf(input2));
}
/ 示例 output 應類似於以下內容:
input user:
10
20
20
30
30
40
50
if -1 is inputted, the user will exit the loop
Number you are searching for in an array list?: the user again input the desired number 30
number 30 is at index 3
number 30 is at index 4
我怎樣才能像上面一樣顯示頻繁數的索引^?
如果我正確理解您的問題,您可以這樣做:
System.out.println("search for? ");
int input2 = scanner.nextInt();
for(int i =0; i<arrayList.size();i++){
if(arrayList.get(i)==input2){
System.out.println(input2 + " is at index " + i); //e.g. 30 is at index 3
}
}
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