返回的 hashmap 值为 null
我将自己限制在问题中我出错的部分。我有一个双精度值数组;我将数组中所有非零值放入哈希映射中,但是当我尝试在哈希映射中显示值时,我得到空值。 需要帮助。我无法弄清楚这是否与 Java 集合有关。
Map 是在 for 循环之外创建的。
for(int i=0;i<aray.length;i++) {
if(aray[i]!=0) {
//non zero array values get divided by some random number not too big number.
aray[i]=aray[i]/somenumber;
hashmap.put(i,aray[i]);
System.out.println(hashmap.get(i));
//if I display aray[i] its a non zero number but hashmap.get(i) is returning null values.
}
}
I am restricting myself to just to the part of the question where I am going wrong. I have an array of double values; I put all the values of the array which are non zero into the hash map but when I am trying to display the values in my hashmap I get null values.
Help needed.I have not been able to figure out if this has got something to with Java Collections.
The Map is created outside the for loop.
for(int i=0;i<aray.length;i++) {
if(aray[i]!=0) {
//non zero array values get divided by some random number not too big number.
aray[i]=aray[i]/somenumber;
hashmap.put(i,aray[i]);
System.out.println(hashmap.get(i));
//if I display aray[i] its a non zero number but hashmap.get(i) is returning null values.
}
}
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对我有用。
程序
输出
正如预期的那样,任何地方都没有空值。我看不出地图会返回空值,因为您刚刚添加了该值。
Works for me.
Program
Output
No null values anywhere, as expected. I don't see any way the map would be returning nulls, since you've just added the value.