如何在java中的arraylist中的单词中间添加字符?

问题描述

我正在练习 ArrayList 的.我试图做到这样，每次 is 在 ArrayList 中时，后面跟着 not.例如[is sky, is, this is blue, is, is not] 运行该方法后，结果为[is not sky, is not, this is not blue, is不是不是，不是不是].但是，现在我的代码不会改变.我是 Java 新手，所以我非常感谢您的指点！

I'm practicing ArrayList's. I'm trying to make it so that every time is is in the ArrayList, it is then followed with not. For instance [is sky, is, this is blue, is is, is not] after running through the method comes out as [is not sky, is not, this is not blue, is not is not, is not not]. However, with my code right now it does not change. I am new to Java, so I would really appreciate any pointers!

class Main {
    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<String>();

        list.add("is sky");
        list.add("is");
        list.add("this is blue");
        list.add("is is");
        list.add("is not");

        System.out.println(replace(list));
    }

    public static ArrayList<String> replace(ArrayList<String> list) {
        for (int i = 0; i < list.size(); i++) {
            if (list.subList(i, i + 1).equals("is")) {
                list.add(i + 1, " not");
            }
        }
        return list;
    }
}

推荐答案

先解决最简单的情况.暂时忘记列表，只用一个 String 进行替换.

First solve the simplest case. Forget the list for a moment and do the substitution with just one String.

String replaceOne(String original) {
    return original.replace("is", "is not");
}

测试这个方法.

String replaced = replaceOne("sky is");

如果这个replaced变量等于sky is not，则测试通过.

The test passes if this replaced variable is equal to sky is not.

一旦你保证了这一点，就用一个列表来处理一般情况.

Once you've guaranteed that, move on to the general case, with a list.

void replaceMany(ArrayList<String> original) {
    for (int i = 0; i < original.size(); i++) {
        original.set(i, replaceOne(original.get(i)));
    }
}

请注意，如果您在静态方法中运行它，则上述方法必须是静态的(即 static void、static String).

Note that if you're running this inside a static method, the above methods need to be static (i.e. static void, static String).

使用 Java 8，您还可以以不同的方式解决这个问题.除了在数组列表上使用 set 方法之外，您还可以使用 lambdas 和收集器来获取修改后的列表(保留原始列表并使用修改后的字符串获取另一个列表).类似的东西:

With Java 8 you could also solve this problem differently. Instead of using the set method on the array list, you could use lambdas and a collector to get a modified list (preserve the original and get another list with the modified strings). Something like:

List<String> replaced = original.stream()
    .map(s -> replaceOne(s))
    .collect(Collectors.toList());

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