有一个Vector里面存放一组值,我想取出尽量三组不同的值,请熟悉的人给发方法,多谢

Question

下面是我写的方法,但感觉应该是不多,请高手指点一下,最后也能写出代码,谢谢:
public static String[] getElementFromVector(Vector vector){
int i = 0;
String str[] = null;
String strData[] = null;
str = new String[15];
strData = new String[3];

Enumeration e = vector.elements();
while(e.hasMoreElements()){
str[i] = (String)e.nextElement();
if(str[i].compareTo(str[i-1])>0){
strData[i] = str[i];
}
else
strData[i] = str[i-1];

i++;
} return strData;
}

Answer 1

我修改了下,请帮我看看是否正确
    public static String[] getElementFromVector(Vector vector) {
        String strData[] =   new String[3];
        String a="";
        int s=0;
        Enumeration e = vector.elements();
        while (e.hasMoreElements()) {
           String vv = (String)e.nextElement();
           if(a.indexOf(vv+",")<0){
              a+=vv+",";
             strData[s]=vv;
               s++;
           }            
        }
        for (int i = 0; i < strData.length; i++) {
            String s1 = strData[i];
            if(s1==null)
            {
                strData[i]=strData[0];
            }
        }        return strData;
    }

Answer 2

import java.util.*;public class Test4{
public static void main(String[] args){
        Vector<String> myVector=new Vector<String>(Arrays.asList("1","1","2","3","2","4","3"));
        String[] result=getElementFromVector(myVector,3);
        System.out.println(Arrays.toString(result)); }
public static String[] getElementFromVector(Vector<String> vector,int count){ 
Set<String> mySet=new HashSet<String>(vector);
if(mySet.size()<count){
System.out.println("不相同的元素数量不够");
}
String[] result=new String[count];
int index=count-1;
for(String str:mySet){
if(index<0){
break;
}
result[index--]=str;
}
return result;
}

}

Answer 3

bigbug9002谢谢你的热心帮忙啊,那么我上面的实现方法有问题吗?

Answer 4

我看不懂你的代码,下面是我的代码,我估计你也看不懂我的代码.
好在我的代码能出来结果:
import java.util.*;public class Test4{
public static void main(String[] args){
        Vector<String> myVector1=new Vector<String>(Arrays.asList("1","1","1","1","1","4","1"));
        Vector<String> myVector2=new Vector<String>(Arrays.asList("1","1","3","1","2","4","1"));
        String[] result1=getElementFromVector(myVector1,3);
        String[] result2=getElementFromVector(myVector2,3);
        System.out.println(Arrays.toString(result1));
        System.out.println(Arrays.toString(result2)); }
public static String[] getElementFromVector(Vector<String> vector,int count){ 
Set<String> mySet=new HashSet<String>(vector);
String[] result=new String[count];
int index=count-1;
for(String str:mySet){
if(index<0){
break;
}
result[index--]=str;
}
if(index>=0){
for(String str:vector){
result[index--]=str;
if(index<0){
break;
}
}
}
return  result;
}}F:\java>java Test4
[1, 4, 1]
[1, 2, 3]

Answer 5

我是在J2ME下写的,所以最好是用String ,String[], Vector来实现,其他的类型怕是不支持

Answer 6

import java.util.*;public class Test4{
public static void main(String[] args){
        Vector<String> myVector1=new Vector<String>(Arrays.asList("4","1","1","1","1","1","1"));
        Vector<String> myVector2=new Vector<String>(Arrays.asList("1","1","3","1","2","4","1"));
        String[] result1=getElementFromVector(myVector1,3);
        String[] result2=getElementFromVector(myVector2,3);
        System.out.println(Arrays.toString(result1));
        System.out.println(Arrays.toString(result2)); }
public static String[] getElementFromVector(Vector<String> vector,int count){ 
Map<String,Integer> myMap=new HashMap<String,Integer>();
for(int i=0;i<vector.size();i++){
myMap.put(vector.get(i),i);
}
String[] result=new String[count];
int index=count-1;
for(String str:myMap.keySet()){
if(index<0){
break;
}
result[index--]=str;
}
if(index>=0){
boolean isAll=false;
for(int i=0;i<vector.size()&&!isAll;i++){
for(int j=count-1;j>index;j--){
String str=vector.get(i);
if(str.equals(result[j])&&myMap.get(str).intValue()!=i){
result[index--]=str;
if(index<0){
isAll=true;
break;
}
}
}
}
}
return  result;
}}
这个应该是没有问题的.

Answer 7

Map应该有吧
简化一下算法：import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Vector;public class Test4{
    public static void main(String[] args){
     Vector<String> myVector;
     String[] result;
    
        myVector=new Vector<String>(Arrays.asList("1","1","1","1","3","4","1"));
        result=getElementFromVector(myVector,3);
        System.out.println(Arrays.toString(result));
        
        myVector=new Vector<String>(Arrays.asList("1","1","1","1","1","4","1"));
        result=getElementFromVector(myVector,3);
        System.out.println(Arrays.toString(result));
        
        myVector=new Vector<String>(Arrays.asList("1","1","1","1","1","1","1"));
        result=getElementFromVector(myVector,3);
        System.out.println(Arrays.toString(result));    }
    public static String[] getElementFromVector(Vector<String> vector,int count){ 
        String[] result=new String[count];     Map<String, Integer> myMap = new HashMap<String, Integer>();
for(String str:vector){
if(myMap.get(str) == null){
myMap.put(str, 1);
}else{
myMap.put(str, myMap.get(str) + 1);
}
}

while (count > 0){
    for(String str : myMap.keySet()){
            if(count <= 0){
             break;
            }
            if(myMap.get(str) > 0){
            result[--count]= str;
            myMap.put(str, myMap.get(str) - 1);
            }
    }
    }
        return result;
    }
    
}

Answer 8

                if(count <= 0){
                    break;
                }
是多余的，可以去掉

Answer 9

public static List getElementFromVector(Vector vector) { 
        List strData =  new ArrayList(); 
        
        if (vector != null && vector.size() >=3) {
        strData.add(vector.get(0));
        for (int i = 1; i < vector.size(); i++) {
         if (!strData.contains(vector.get(i))) {
         strData.add(vector.get(i));
}
         if (strData.size() >= 3) {
         break;
         }
        }
        
        if (strData.size() == 1) {
         strData.add(strData.get(0));
         strData.add(strData.get(0));
        }
        if (strData.size() == 2) {
         if (strData.get(1).equals(vector.get(1))) {
         strData.add(vector.get(2));
} else {
strData.add(1,vector.get(1));
}
        }
        }
        return strData; 
    }