Java下List<Long>转List<String>或者List<Long>转List<Integer>

说明：很遗憾，没有快速方法，只能遍历然后循环增加进去。

方法：

for(String str : list) {
  int i = Integer.paseInt(str);
  intList.add(i);
} 

如果借助第三方类库可以这样实现：

import java.lang.reflect.Method;
import java.util.List;
public class RunTime {
    public static long invokeStaticMethod(String clsName, String methodName,
            Object[] args) throws Exception {
        long start = System.nanoTime();
        try {
            Class c = Class.forName(clsName);
            Class[] argsClass = new Class[] {List.class};
            Method method = c.getMethod(methodName, argsClass);
            method.invoke(c, args);
        } catch (Exception e) {
            e.printStackTrace();
        }
        long end = System.nanoTime();
        return end - start;
    }
}

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
 
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.Transformer;
public class Test {
 
    /**
     * @param args
     */
    public static List<Integer> StringToIntegerLst(List<String> inList){
        List<Integer> iList =new ArrayList<Integer>(inList.size());
        try{   
           for(int i=0,j=inList.size();i<j;i++){
             iList.add(Integer.parseInt(inList.get(i)));   
           }   
          }catch(Exception  e){
        }
        return iList;
    }
    public static List<Integer> CollStringToIntegerLst(List<String> inList){
        List<Integer> iList =new ArrayList<Integer>(inList.size());
        CollectionUtils.collect(inList, 
                  new Transformer(){
                    public java.lang.Object transform(java.lang.Object input){
                      return new Integer((String)input);
                    }
                  } ,iList );
        return iList;
    }
    public static void main(String[] args) {
        List<String> sList = new ArrayList<String>();
        for (int i=0;i<1000;i++) { 
            sList.add(String.valueOf(i));
        }
        Object[] param=new Object[]{sList};
        try {
            long runTime=RunTime.invokeStaticMethod("com.jsoft.common.Test", "StringToIntegerLst", param);
            System.out.println("采用顺序转化方法执行时间"+runTime);
            long runTimeByColl=RunTime.invokeStaticMethod("com.jsoft.common.Test", "CollStringToIntegerLst", param);
            System.out.println("采用org.apache.commons.collections.CollectionUtils执行时间"+runTimeByColl);
            System.out.println("微秒相差(runTimeByColl-runTime)=" +String.valueOf(runTimeByColl-runTime));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

 

参考：

http://bbs.csdn.net/topics/310077387