[JavaScript知识库]用亲爱的java重新实现js中巨好用的reduce

package js_method;

import java.util.List;

/**
 * T_INIT -- initValue Type
 * T_ARRAY -- array type
 */
public interface CallBack<T_INIT,T_ARRAY> {
    T_INIT callBack(T_INIT initValue,T_ARRAY element,int index, List<T_ARRAY> arr);
}

package js_method;

import java.util.List;

public abstract class Reduce<INITVALUE_TYPE,ARRAY_TYPE> implements CallBack<INITVALUE_TYPE,ARRAY_TYPE>{
    @Override
    public abstract INITVALUE_TYPE callBack(INITVALUE_TYPE initValue, ARRAY_TYPE element, int index, List<ARRAY_TYPE> arr);
    public INITVALUE_TYPE reduce(List<ARRAY_TYPE> array,CallBack<INITVALUE_TYPE,ARRAY_TYPE> callBack,INITVALUE_TYPE initvalue) throws Exception {
        if(array==null) throw new Exception("must have array!!!");
        if(callBack==null) throw new Exception("must have callback function!!!");
        int i=0;
        if(initvalue == null){
            while(i<array.size()){
                if(array.get(i)!=null){
                    initvalue= (INITVALUE_TYPE) array.get(i);
                    i++;
                    break;
                }
                i++;
            }
        }
        for(;i<array.size();i++){
            initvalue=callBack(initvalue,array.get(i),i,array);
        }
        return initvalue;
    }
}

package js_method;

import java.util.Arrays;
import java.util.List;

public class UseReduce {
    public static void main(String[] args) throws Exception {
        Reduce<Integer,Integer> reduce = new Reduce<Integer, Integer>() {
            @Override
            public Integer callBack(Integer initValue, Integer element, int index, List<Integer> arr) {
                return initValue+element;
            }
        };
        Integer reduceRes = reduce.reduce(Arrays.asList(1, 2, 3, 4, 5), reduce, null);
        System.out.println(reduceRes);

    }

}