java - C++ 结构到 Java 类

Question

我想像这样转换一个 C++ 结构:

typedef struct FEATUREINFO
{
    string str_ID;
    char* c_ID;
    double* featureData;
    int group;
    bool bPrint;
    IplImage *t_faceImg;
}FEATUREINFO;

我会用它:

FEATUREINFO * p_featureNode = new FEATUREINFO[100];
for(int j=0; j<100 ; j++)
{
    p_featureNode[j].featureData = (double*)calloc(t_featureLen,sizeof(double));
    p_featureNode[j].bPrint = false;
}

在 Java 代码中我写了我的代码:

class FEATUREINFO
{
    string str_ID;
    char[] c_ID;
    public Double[] featureData;
    int group;
    public boolean bPrint;
    //IplImage *t_faceImg;
    public FEATUREINFO()
    {
        this.featureData = new Double[1280] ;
    }     
} // class FEATUREINFO

然后写一段简单的代码来测试我是否成功:

FEATUREINFO[] p_featureNode = new FEATUREINFO[100];
p_featureNode[5].featureData[2] = 100.5 ;  // this line will error!!! =(
Log.d(Tag_Test, "featureData :" + p_featureNode[5].featureData[2] ) ;     

我是Java初学者，请帮助我!非常感谢!

我的错误是: http://i.imgur.com/lwUaSTg.png

再次感谢!!!! =D

Answer 1

C++ 将每个数组元素初始化为默认状态(为每个数组元素调用默认构造函数)- Java 不会。

你需要这样的东西:

FEATUREINFO[] p_featureNode = initializeWithDefaultFEATUREINFOInstances(100);
...

public static FEATUREINFO[] initializeWithDefaultFEATUREINFOInstances(int length)
{
    FEATUREINFO[] array = new FEATUREINFO[length];
    for (int i = 0; i < length; i++)
    {
        array[i] = new FEATUREINFO();
    }
    return array;
}