如何从java中删除数组中的重复元素？ [英] How to remove duplicate elements from array in java?

问题描述

给我一​​些示例和代码，以便我以后可以试试



我尝试过：



i想要尝试这个但我无法获得精确的代码

Give me some example and codes for this so that i can try it later

What I have tried:

i want to try this but i cant get the excact code

推荐答案

从这里开始：16如何从java中的数组中删除元素 - YouTube [ ^ ]



而不是数组，我建议使用 ArrayList [ ^ ]实现了删除方法。

请参阅：

Java.util.ArrayList.remove(object）方法示例 [ ^ ]

Java.util.ArrayList.remove（int index）方法示例 [ ^ ]

Start here: 16 How to delete An Element from an array in java - YouTube[^]

Instead of array, i'd suggest to use ArrayList[^] which implements remove method.
See:
Java.util.ArrayList.remove(object) Method Example[^]
Java.util.ArrayList.remove(int index) Method Example[^]

好了，你可以试试这个例子来回答你的问题

ok here, You can try this example for you to answer your question

import java.util.Arrays;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Java program to remove duplicates from this array. You don't
 * need to physically delete duplicate elements, replacing with null, or
 * empty or default value is ok.
 *
 * @author http://javarevisited.blogspot.com
 */
public class TechnicalInterviewTest {

    private static final Logger logger = LoggerFactory.getLogger(TechnicalInterviewTest.class);

    public static void main(String args[]) {

        int[][] test = new int[][]{
            {1, 1, 2, 2, 3, 4, 5},
            {1, 1, 1, 1, 1, 1, 1},
            {1, 2, 3, 4, 5, 6, 7},
            {1, 2, 1, 1, 1, 1, 1},};

        for (int[] input : test) {
            System.out.println("Array with Duplicates       : " + Arrays.toString(input));
            System.out.println("After removing duplicates   : " + Arrays.toString(removeDuplicates(input)));
        }
    }

    /*
     * Method to remove duplicates from array in Java, without using
     * Collection classes e.g. Set or ArrayList. Algorithm for this
     * method is simple, it first sort the array and then compare adjacent
     * objects, leaving out duplicates, which is already in result.
     */
    public static int[] removeDuplicates(int[] numbersWithDuplicates) {

        // Sorting array to bring duplicates together      
        Arrays.sort(numbersWithDuplicates);     
      
        int[] result = new int[numbersWithDuplicates.length];
        int previous = numbersWithDuplicates[0];
        result[0] = previous;

        for (int i = 1; i < numbersWithDuplicates.length; i++) {
            int ch = numbersWithDuplicates[i];

            if (previous != ch) {
                result[i] = ch;
            }
            previous = ch;
        }
        return result;

    }
}

Output :
Array with Duplicates       : [1, 1, 2, 2, 3, 4, 5]
After removing duplicates   : [1, 0, 2, 0, 3, 4, 5]
Array with Duplicates       : [1, 1, 1, 1, 1, 1, 1]
After removing duplicates   : [1, 0, 0, 0, 0, 0, 0]
Array with Duplicates       : [1, 2, 3, 4, 5, 6, 7]
After removing duplicates   : [1, 2, 3, 4, 5, 6, 7]
Array with Duplicates       : [1, 2, 1, 1, 1, 1, 1]
After removing duplicates   : [1, 0, 0, 0, 0, 0, 2]

你可以尝试这个

You can try this

import java.util.Arrays;

public class Removeduplicates {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

int[] a = { 3, 1, 1, 4, 1, 4, 5 };

Arrays.sort(a);
int count = 0;

long start = System.currentTimeMillis();

for (int i = 0; i < a.length; i++) {
if (i + 1 < a.length && a[i] == a[i + 1]) {
count++;
}

}

int[] b = new int[a.length - count];
int c = 0;
for (int j = 0; j < a.length; j++) {
if (j + 1 < a.length && a[j] == a[j + 1]) {

} else {
b[c] = a[j];
c++;
}
}

a = b;
System.out.println(Arrays.toString(a) + "took"
+ (System.currentTimeMillis() - start));

}
}

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