基本上我想為我在 public static void main 中創(chuàng)建的“方法”創(chuàng)建一個(gè)單獨(dú)的方法。在這個(gè)方法中，我操作了一個(gè)數(shù)組列表，但不確定如何使用數(shù)組列表作為函數(shù)中的參數(shù)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(yǔ)法，但找不到任何顯示語(yǔ)法的好視頻。
2 回答
翻閱古今
TA貢獻(xiàn)1780條經(jīng)驗(yàn) 獲得超5個(gè)贊
ArrayList實(shí)現(xiàn)List，因此您可以將其用作參數(shù)，例如
public void testMethod(List<String> list){
//....rest of your code goes here
}
始終記住，對(duì)象是通過(guò)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(diào)用該方法的方法中的列表中。
另外，對(duì)于您的代碼，java 支持菱形運(yùn)算符，即您不需要在 的右側(cè)指定泛型類型=。左邊，即為了可維護(hù)性，參考變量應(yīng)該是父接口，例如
List<String> list = new ArrayList<>();
慕萊塢森
TA貢獻(xiàn)1810條經(jīng)驗(yàn) 獲得超4個(gè)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);
}
}
}
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