小编The*_*Egg的帖子

对于我的CS赋值,我需要编写一个实现容器接口的通用Bag对象.Bag应该只能容纳实现Thing界面的项目.我的问题是,当我尝试编译时,我得到了这个......

Bag.java:23: error: cannot find symbol
    if (thing.getMass() + weight >= maxWeight) {
symbol:   method getMass()
location: variable thing of type Thing
where thing is a type-variable:
  Thing extends Object declared in class Bag

getMass()方法在Thing界面中有明确定义,但我无法让Bag对象找到它.这是我的班级文件......

public interface Thing {
    public double getMass();
}

public class Bag<Thing> implements Container<Thing> {
    private ArrayList<Thing> things = new ArrayList<Thing>();
    private double maxWeight = 0.0;
    private double weight = 0.0;

    public void create(double maxCapacity) {
    maxWeight = maxCapacity;
    }

    public void insert(Thing thing) throws OutOfSpaceException …

我试图在C中通过引用传递结构,以便我可以修改函数内的值.这是我到目前为止的代码,但它会产生一些警告和一个错误.

main.c中

#include <stdio.h>
#include "myfunctions.h"
#include "structures.h"

int main(int argc, char const *argv[] {

    struct MyStruct data;

    data.value = 6;

    printf("Before change: %d\n", data.value);

    changeData(data);

    printf("After change: %d\n", data.value);

}

myfunctions.c

#include "structures.h"

void changeData(MyStruct data) {
    data.value = 7;
}

myfunctions.h

#ifndef MyStruct
#define MyStruct

void changeData(MyStruct data);

#endif

structures.h

typedef struct {

    int value;

} MyStruct;

产生的错误

In file included from main.c:2:0:
myfunctions.h:4:1: warning: parameter names (without types) in function declaration
 void changeData(MyStruct data);
 ^
In file …