// class
@SuppressWarnings({ "unchecked", "rawtypes" })
	static
	List<Entry>[] oList = new LinkedList[2000];
	LinkedList<Entry> newoList;

// main
// for 循环查找
		ArrayList<Hero> lst1 = new ArrayList<>();
		for(int i = 0; i < 100000; i++) {
			 int j = (int)(Math.random()*(9999 - 1000 + 1) + 1000);
	         lst1.add(new Hero("hero-" + j));
		}
		long time1 = System.currentTimeMillis();
        for (Hero h: lst1) {
            if (h.name.contains("hero-5555")) {
            	System.out.println("找到名为hero-5555的英雄，他的序列号是: " + lst1.indexOf(h));
            }      
        }
        long time2 = System.currentTimeMillis();
        long tim1 = time2- time1;
        System.out.printf("使用for循环查找\"hero-5555\",耗时%dms\n", tim1);
        System.out.println("************************");
        
        // 使用MyHashMap查找
        MyHashMap mh = new MyHashMap();
        int i = 0;
        
		for(Hero h: lst1) {
			mh.put(String.valueOf(hashcode(String.valueOf(i))), h); // 
			i++;
		}
		long time3 = System.currentTimeMillis();
		for(int j = 0; j < mh.oList.length; j++) {
			if(oList[j] != null) {
				for(int k = 0; k < oList[j].size(); k++) {				
					if(oList[j].get(k).value.toString().equalsIgnoreCase("hero-5555"))
						System.out.println("找到名为hero-5555的英雄，他的序列号是: " + j + ":[" + k +":" +oList[j].get(k).value.toString() + "]");
				}
			}
		}
        long time4 = System.currentTimeMillis();
        long tim2 = time4 - time3;
        System.out.printf("使用MyHashMap循环查找\"hero-5555\",耗时%dms\n", tim2);

// 调用以下函数
public void put(String key, Object value) {
			
	if (oList[Integer.parseInt(key)] == null) {
		Entry e = new Entry(key,value);
		newoList = new LinkedList<>();
		newoList.add(e);
		oList[Integer.parseInt(key)] = newoList;
	}else {
		Entry e = new Entry(key,value);
		newoList.addLast(e);
		oList[Integer.parseInt(key)] = newoList;
	}
	
}

public Object get(String key) {
	Object v = null; 
	if (oList[Integer.parseInt(key)] == null) {
		return null; 
	}else {
		for(Entry o : oList[Integer.parseInt(key)]) {
			if(o.key.equals(key)) {
				v = o.value;
				break;
			}else {
				return null;
			}
		}
			
		return v; 
	}
}

public static int hashcode(String s) {
	int hc = 0;
	if(s.length() != 0) {
		for(int j = 0; j < s.length(); j++) {
			hc += Integer.parseInt(String.valueOf(s.charAt(j)));   
		}
		hc *= 23;
		if(hc > 1999)
			hc %= 2000;
		if(hc < 0)
			hc = Math.abs(hc);
	}	
	else 
		hc = 0;
	return hc;
}

//创建一个长度是len的随机数字字符串
public static String getString(int len) {
	char[] cs = new char[len];
	for(int j = 0; j < len; j++) {
		cs[j] = (char)(Math.random()*('9' - '0' + 1) + '0');    
	}
	String s = new String(cs);
	return s;
}

public static int hashcode(String str) {
    	if (str.length() == 0)
    		return 0;
    	else {
    		char[] cs = str.toCharArray();
    		int sum = 0;
    		for (char c : cs) {
    			int num = Integer.parseInt(String.valueOf(c));
    			System.out.println(num);
    			num = num<0 ? 0-num : num;
    			sum += num;
    		}
    		sum *= 23;
    		sum = sum<0 ? 0-sum : sum;
    		sum %= 2000;
    		return sum;
    	}
    }

Exception in thread "main" java.lang.NumberFormatException: For input string: "H"
	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)
	at java.base/java.lang.Integer.parseInt(Integer.java:668)
	at java.base/java.lang.Integer.parseInt(Integer.java:786)
	at collection.TestCollection.hashcode(TestCollection.java:24)
	at collection.TestCollection.main(TestCollection.java:11)

public static void main(String[] args) {
        for(int i=0;i<100;i++){
            int length= (int) (Math.random()*8+2);
            String str=random(length);
            int hashcode=hashcode(str);
            System.out.println(str+"hashcode="+hashcode);
        }

     

    }

    static String random(int length){
        String s="";
        for(short i='0';i<='9';i++){
            s+=(char)i;
        }
        for(short i='a';i<='z';i++){
            s+=(char)i;
        }
        for(short i='A';i<='Z';i++){
            s+=(char)i;
        }
        char[] c=new char[length];
        for(int i=0;i<c.length;i++){
            int index= (int) (Math.random()*s.length());
            c[i]=s.charAt(index);
        }
        String result=String.valueOf(c);
        return result;
    }
    public static int hashcode(String s){
        if(0==s.length()){
            return 0;
        }
        int hashCode=0;
        char[] c=s.toCharArray();
        for(int i=0;i<c.length;i++){
            hashCode+=c[i];
        }
        hashCode*=23;
        hashCode=hashCode<0?0-hashCode:hashCode;
        hashCode=hashCode>1999?hashCode%2000:hashCode;
        return hashCode;
    }

// 十万个
		ArrayList<Hero> lst1 = new ArrayList<>();
		ArrayList<Integer> lst2 = new ArrayList<>();

		for (int i = 0; i <100000; i++) {
        	int j = (int) (Math.random()*(1000 + 9999));
        	lst1.add(new Hero("hero-" + j));
        }
		
		// 查找hero-5555的对象
        long time1 = System.currentTimeMillis();
        for (Hero h: lst1) {
        	if (h.name.contains("hero-5555"))
        		lst2.add(lst1.indexOf(h));
        }
        long time2 = System.currentTimeMillis();
        long tim1 = time2- time1;
		System.out.printf("使用for循环查找\"hero-5555\",耗时%dms\n", tim1);
		
		MyHashMap heroMap = new MyHashMap();
		long time3 = System.currentTimeMillis();
		for (Hero h: lst1) {
        	if (h.name.contains("hero-5555"))
        		heroMap.put("hero-5555", h);
        }
	    long time4 = System.currentTimeMillis();
		long tim2 = time4- time3;
		System.out.printf("使用hashMap查找\"hero-5555\",耗时%dms\n", tim2);

import java.util.LinkedList;
import collection.Entry; 
import collection.TestCollection;

public class MyHashMap implements IHashMap {

	// 长度是2000的对象数组
	@SuppressWarnings("unchecked")
	LinkedList<Entry>[] Olist = new LinkedList[2000];
	
	@Override
	public void put(String key, Object object) {
		// TODO 自动生成的方法存根
		int hashcode = TestCollection.hashcode(key);
		if (Olist[hashcode] == null) {
			// 在作用域中，没有任何Entry的外层实例可访问   Entry.super;
			Entry e = new Entry(key, object);
			Olist[hashcode] = new LinkedList<Entry>();
			Olist[hashcode].add(e);
		}	
		else {
			Entry e = new Entry(key, object);
			Olist[hashcode].addLast(e);
		}
	}

	@Override
	public Object get(String key) {
		// TODO 自动生成的方法存根
		int hashcode = TestCollection.hashcode(key);
		Object v = null; 
		if (Olist[hashcode] == null) {
			// 在作用域中，没有任何Entry的外层实例可访问   Entry.super;
			return null;
		}	
		else {
			for (Entry o : Olist[hashcode]) {
				if(o.key.equals(key)) {
					v = o.value;
					break;
				}
				else
					return null;
			}
			return v;
		}
		
	}
}