java - 显示给定ArrayList反向的Java代码

Question

因此，我试图编写一种方法，该方法返回给定ArrayList的逆向，但它给我Index错误，而且我不知道如何解决。我感谢您的帮助。这是我的代码:

import java.util.ArrayList;

public class question2 {

public static ArrayList<Double> reverse(ArrayList<Double> arraylist) {
    ArrayList<Double> result = new ArrayList<Double>();
    for(int i=0; i<arraylist.size(); i++) {
        result.set((arraylist.size()) - 1 - i, arraylist.get(i));
    }
    return result;
}

public static void main(String[] args) {
    
    ArrayList<Double> doubles = new ArrayList<Double>();
    doubles.add(1.5);
    doubles.add(2.3);
    doubles.add(7.7);
    doubles.add(8.6);
    System.out.println(reverse(doubles));
    
}

}

这是错误:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 3 out of bounds for length 0

Answer 1

public static ArrayList<Double> reverse(ArrayList<Double> arraylist) {
       ArrayList<Double> result = new ArrayList<Double>(arraylist.size());
        for(int i=arraylist.size()-1; i>=0; i—-) {
            result.add(arraylist.get(i));
        }
        return result;
     }

希望这会成功!