在 Java 中将列表分成两半
在这里，我们得到了一个列表，任务是将它分成两个新闻列表，如下图所示:
插图:
Input : list = {1, 2, 3, 4, 5, 6}
Output : first = {1, 2, 3}, second = {4, 5, 6}
Input : list = {1, 2, 3, 4, 5}
Output : first = {1, 2}, second = {3, 4, 5}
方法:
- Use cycle (naive method)
- The List class using the subList () method
- 使用分区依据()方法的收集者类
- Use Google guava library
让我们讨论一下上面定义的方法的细节，并通过干净的 java 程序实现如下:
方法 1: 使用循环
方法:
- Create two new empty lists and assign the first half elements of the original list.
- Reset to enter the second empty list.
示例:
Java
// Java Program to Split a List into Two Sublist
// Importing required classes
import java.util.ArrayList;
import java.util.List;
// Main class
public class GFG {
// Method 1
// To split a list into two sublists in Java
public static List[] split(List<String> list)
{
// Creating two empty lists
List<String> first = new ArrayList<String>();
List<String> second = new ArrayList<String>();
// Getting size of the list
// using size() method
int size = list.size();
// Step 1
// (First size)/2 element copy into list
// first and rest second list
for (int i = 0; i < size / 2; i++)
first.add(list.get(i));
// Step 2
// (Second size)/2 element copy into list first and
// rest second list
for (int i = size / 2; i < size; i++)
second.add(list.get(i));
// Returning a List of array
return new List[] { first, second };
}
// Method 2
// Main driver method
public static void main(String[] args)
{
// Creating an ArrayList of string type
List<String> list = new ArrayList<String>();
// Adding elements to list object
// using add() method
list.add("Geeks");
list.add("Practice");
list.add("Contribute");
list.add("IDE");
list.add("Courses");
// Calling split method which return List of array
List[] lists = split(list);
// Printing specific elements of list by
// passing arguments with in
System.out.println(lists[0]);
System.out.println(lists[1]);
}
}
输出
[Geeks, Practice]
[Contribute, IDE, Courses]
方法 2: 使用 List 类的 subList()方法
它返回此列表中指定索引(包括)到另一个索引(排除)之间的部分的视图。例如，让我们从 2 到 5 任意取值，这里索引 2 将只包括。如果两个指定的索引相等，则返回的列表为空。List.subList()返回了一个列表，因此返回列表中的非结构性更改。
例:
爪哇
// Java Program to Split a List into Two SubList
// Using subList() method of List clas
// Importing required classes
import java.util.ArrayList;
import java.util.List;
// Main class
public class GFG {
// Method 1
// To split a list into two sublists in Java
public static List[] split(List<String> list)
{
// Finding the size of the list using List.size()
// and putting in a variable
int size = list.size();
// Creating new list and inserting values which is
// returned by List.subList() method
List<String> first
= new ArrayList<>(list.subList(0, (size) / 2));
List<String> second = new ArrayList<>(
list.subList((size) / 2, size));
// Returning an List of array
return new List[] { first, second };
}
// Method 2
// Main driver method
public static void main(String[] args)
{
// Creatingan ArrayList of String type
List<String> list = new ArrayList<String>();
// Adding elements to List object
// Custom input elements
list.add("Geeks");
list.add("Practice");
list.add("Contribute");
list.add("IDE");
list.add("Courses");
// Calling split method which return List of array
List[] lists = split(list);
// Printing specific elements of list by
// passing arguments with in
System.out.println(lists[0]);
System.out.println(lists[1]);
}
}
输出
[Geeks, Practice]
[Contribute, IDE, Courses]
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