查找数组中的数字或字符或字符串出现的次数——大家写一写

Question

1.如何查找数组中的数字出现的次数
例如：Integer[] nums=new Integer[]{10,5,6,9,8,7,4,5,4,210,2,5,8,9,6,3,7,4,9};中有哪些数字？各出现了几次？2.如何查找数组中的字符出现的次数
例如：Character[] nums=new Character[]{'0','a','a','a','*','&','0'};中有哪些字符？各出现了几次？3.如何查找数组中的字符串出现的次数
例如：String[] nums=new String[]{"abc","abc","abc","000","000","gaopan","gao","gao"};中有哪些字符串？各出现了几次？4.如果是对象呢？（选答）

Answer 1

前面写过的一个import java.util.*;
public class Test3
{
    public static void main(String[] args)
    {
        int num = 1;
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        Integer[] is = {1,2,1,3,2,1,3,2,3,4};
        Arrays.sort(is);
        for(int i = 0;i<is.length; i++){
            if(i !=(is.length-1)){
                if(is[i]==is[i+1]){
                    num++;
                }
                if(is[i]!=is[i+1]){
                    map.put(is[i],num);
                    num = 1;
                }
            }
            else{
                if(is[i]==is[i-1]){
                    map.put(is[i],num);
                }
                else{
                    map.put(is[i],1);
                }
            }
        }
        
        System.out.println(map.toString());
    }
}

Answer 2

import java.util.*;
class SearchArray 
{
public static <T> HashMap<T, Integer> search(T[] array)
{
int num = 1;
HashMap<T, Integer> map = new HashMap<T, Integer>();
Arrays.sort(array);
for(int i = 0; i < array.length; i++){
if(i != (array.length-1)){
if(array[i].equals(array[i+1])){
num++;
}
else{
map.put(array[i],num);
num = 1;
}
}
else{
if(array[i].equals(array[i-1])){
map.put(array[i],num);
}
else{
map.put(array[i],1);
}
}
}
return map;
}
}public class Test8
{
public static void main(String[] args){
Integer[] nums1=new Integer[]{10,5,6,9,8,7,4,5,4,210,2,5,8,9,6,3,7,4,9};
HashMap<Integer, Integer> map1  = SearchArray.<Integer>search(nums1);
System.out.println(map1.toString());

Character[] nums2=new Character[]{'0','a','a','a','*','&','0'};
HashMap<Character, Integer> map2  = SearchArray.<Character>search(nums2);
System.out.println(map2.toString());

String[] nums3=new String[]{"abc","abc","abc","000","000","gaopan","gao","gao"};
HashMap<String, Integer> map3  = SearchArray.<String>search(nums3);
System.out.println(map3.toString());
}
}