基本上我想為我在 public static void main 中創建的“方法”創建一個單獨的方法。在這個方法中，我操作了一個數組列表，但不確定如何使用數組列表作為函數中的參數import java.util.ArrayList;public class ReverseArrayList{ public static void main(String[] args) { // Note: I used a sample array with 6 elements. // I explain the code as if I am strictly using 6 elements // However this may be done with any # of elements ArrayList<String> reverseMe = new ArrayList<String>(); reverseMe.add("I"); reverseMe.add("am"); reverseMe.add("going"); reverseMe.add("to"); reverseMe.add("be"); reverseMe.add("reversed"); // This loop will run until we reach the midpoint of the array. At the midpoint, all the elements would be reversed for (int i = 0; i < reverseMe.size()/2; i++){ // Save the first three values for later use. String initial = reverseMe.get(i); // The 1st element will be assigned to the last element, upto the midpoint reverseMe.set(i, reverseMe.get(reverseMe.size() - i - 1)); // The last element will be assigned to the 1st element, upto the midpoint reverseMe.set(reverseMe.size() - i - 1, initial); } // Displays the contents of the arraylist for(String i: reverseMe){ System.out.println(i); } }}我研究了語法，但找不到任何顯示語法的好視頻。
2 回答
翻閱古今
TA貢獻1780條經驗 獲得超5個贊
ArrayList實現List，因此您可以將其用作參數，例如
public void testMethod(List<String> list){
//....rest of your code goes here
}
始終記住，對象是通過引用傳遞的，因此您在此處的列表中所做的任何修改都將反映在調用該方法的方法中的列表中。
另外，對于您的代碼，java 支持菱形運算符，即您不需要在 的右側指定泛型類型=。左邊，即為了可維護性，參考變量應該是父接口，例如
List<String> list = new ArrayList<>();
慕萊塢森
TA貢獻1810條經驗 獲得超4個贊
you just need something like below
import java.util.ArrayList;
public class ReverseArrayList{
public static void main(String[] args) {
// Note: I used a sample array with 6 elements.
// I explain the code as if I am strictly using 6 elements
// However this may be done with any # of elements
ArrayList<String> reverseMe = new ArrayList<String>();
reverseMe.add("I");
reverseMe.add("am");
reverseMe.add("going");
reverseMe.add("to");
reverseMe.add("be");
reverseMe.add("reversed");
reverseList(reverseMe);
}
private static void reverseList(ArrayList<String> arrayList){
// This loop will run until we reach the midpoint of the array. At the midpoint, all the elements would be reversed
for (int i = 0; i < reverseMe.size()/2; i++){
// Save the first three values for later use.
String initial = reverseMe.get(i);
// The 1st element will be assigned to the last element, upto the midpoint
reverseMe.set(i, reverseMe.get(reverseMe.size() - i - 1));
// The last element will be assigned to the 1st element, upto the midpoint
reverseMe.set(reverseMe.size() - i - 1, initial);
}
// Displays the contents of the arraylist
for(String i: reverseMe){
System.out.println(i);
}
}
}
添加回答
舉報
0/150
提交
取消