从数组中删除空元素（Java）

Question

I'm trying to remove the empty element from the array by copying the existing element to a new array. However, initialization of the new array is causing my return value to be null even when I initialize it within the for loop.

public String[] wordsWithout(String[] words, String target) {
    for(int i = 0; i < words.length; i = i +1){
        String store[] = new String[words.length];
        if (words[i] == target){
            words[i] ="";
        }
        else if(words[i] != target){
            words[i] = store[i];
        }       
    }
    return words;
}

Answer 1

我实际上不确定你想要实现什么，但是如果你想从数组中删除一个空字符串，你可以使用java 8中的流和过滤器来完成它，如下所示：

String[] objects = Arrays.stream(new String[]{"This","", "will", "", "", "work"}).filter(x -> !x.isEmpty()).toArray(String[]::new);

Answer 2

Array are immutable so the size stays the same you need to create a new Array So if you create a new Array base on the Size of the Old array you will still have null elements

If you want to use arrays only you need to count the non null elements in the array to get the size of the new Array. It just easier to use a List/ArrayList

public String[] wordsWithout(String[] words, String target) {
    List<String> tempList=new ArrayList<String>();
    for(int i = 0; i < words.length; i = i +1){

        if (words[i]!=null||words[i].trim().length()>0){
            tempList.add(words[i]);
        }

    }
    return (String[]) tempList.toArray();
}

Answer 3

To check the equality use .equals() method ie string1.equals(string2) and to check non-equality you can use the same method but with not(!) operator ie. !string1.equals(string2). You should declare the store array outside the loop because in each iteration it makes a new object onamed store. In the else condition do this store[i] = words[i].

Answer 4

You shouldn't compare strings using == operator. This is incorrect, because strings are objects. Use .equals() method instead, this should fix your problem.

Rest part of your code is quite confusing, it's hard to understand what you are trying to achieve: you create new string array store each time in loop iterations, and then assign its null (by default) values to words[i] . You should elaborate your code and algorithm.

Answer 5

There are few things Which I am putting as points below. Hope you will get help from this.

1. String store[] = new String[words.length] instantiates an array of Strings but It does not instantiate any of the elements with any non null value. Default value is null so this is an array of null Strings.

2. (words[i] != target) should be replaced with

   (!words[i].equals(target))