在 arrayList 中移动 [英] Shifting in arrayList
本文介绍了在 arrayList 中移动的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
方法public static
接受一个 Arraylist
字符串(至少在这个例子中是这样)和一个 shift
表示数组列表有多少应该转移.如果我有,让我们说一个
The method public static <T> ArrayList<T> rotate(ArrayList<T> aL, int shift)
accepts an Arraylist
of String (at least in this example) and a shift
which indicated how much the arraylist should shift. If I have, let's say an arayList of
[ A, B, C, D, E, F, G]
并且移位是2
,所以方法返回
and the shift is 2
, so the method returns
[ F, G, A, B, C, D, E]
或者另一个例子,
[ A, B, C, D, E, F, G]
和shift
为4
,则方法返回
[ D, E, F, G, A, B, C]
我的方法完全错误,不知道如何解决这个问题.smb 能帮我解决这个问题吗?
I did the method completely wrong and have no clue how to approach this problem. Could smb help me with that ?
import java.util.ArrayList;
public class Rotation{
// Demonstrate rotat(a,shift) method
public static void main(String arg[]){
ArrayList<Character> charsL;
charsL = new ArrayList<Character>();
char [] chars = { 'A', 'B', 'C',
'D', 'E', 'F'};
for(char c : chars){
charsL.add(c);
}
// charsL = [ A, B, C, D, E, F]
ArrayList<Character> result1;
result1 = rotate(charsL, 2);
// result1== [ E, F, A, B, C, D]
System.out.println(result1);
result1 = rotate(charsL, 7);
// result1== [ F, A, B, C, D, E]
System.out.println(result1);
// WORKS WITH SRTINGS TOO
ArrayList<String> stringL;
stringL = new ArrayList<String>();
String [] strs = { "A", "B", "C",
"D", "E", "F", "G" };
for(String s : strs){
stringL.add(s);
}
// stringL = [ A, B, C, D, E, F, G]
ArrayList<String> result2;
result2 = rotate(stringL, 7);
// result2== [ A, B, C, D, E, F, G]
System.out.println(result2);
result2 = rotate(stringL, 4);
// result2== [ D, E, F, G, A, B, C]
System.out.println(result2);
}
public static <T>
ArrayList<T> rotate(ArrayList<T> aL, int shift){
// YOUR DEFINITION HERE
ArrayList <T> newValues = new ArrayList<>();
ArrayList <T> temp = new ArrayList<>();
for(int i = 0; i < aL.size(); i++)
{
newValues.remove(aL.get(shift));
newValues.add(aL.get(i));
//newValues.add(shift, aL.get(i));
}
return newValues;
}
}
推荐答案
试试这个:
public static <T> ArrayList<T> rotate(ArrayList<T> aL, int shift)
{
if (aL.size() == 0)
return aL;
T element = null;
for(int i = 0; i < shift; i++)
{
// remove last element, add it to front of the ArrayList
element = aL.remove( aL.size() - 1 );
aL.add(0, element);
}
return aL;
}
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