java无法使用replaceAll从字符串中删除单词

Question

if(containsAllWeather || containsAllWeather2){

            String weatherLocation = value.toString();

        if (weatherLocation != null){


                weatherLocation.replaceAll("how","")
                        .replaceAll("what","")
                        .replaceAll("weather", "")
                        .replaceAll("like", "")
                        .replaceAll(" in", "")
                        .replaceAll(" at", "")
                        .replaceAll("around", "");
        }

weatherLocation仍然准确地给出变量值包含的内容，并且不会删除上面列出的任何单词

当我将weatherLocation拆分为一个字符串数组（比如weatherLoc数组）时，这些代码行对weatherLoc起作用[1]

我做错了什么

Answer 1

字符串是不可变的。您需要将所有这些replaceAll调用的值分配给一个变量，这就是您想要的

weatherLocation = weatherLocation.replaceAll("how","")
                .replaceAll("what","")
                .replaceAll("weather", "")
                .replaceAll("like", "")
                .replaceAll(" in", "")
                .replaceAll(" at", "")
                .replaceAll("around", "");

Answer 2

String是immutable。因此String.replaceAll返回一个新的instance{}。所以你需要像下面这样使用

weatherLocation = weatherLocation.replaceAll("how","")
                .replaceAll("what","")
                .replaceAll("weather", "")
                .replaceAll("like", "")
                .replaceAll(" in", "")
                .replaceAll(" at", "")
                .replaceAll("around", "");

Answer 3

试试这个：

weatherLocation = weatherLocation.replaceAll("how","")
                        .replaceAll("what","")
                        .replaceAll("weather", "")
                        .replaceAll("like", "")
                        .replaceAll(" in", "")
                        .replaceAll(" at", "")
                        .replaceAll("around", "");

Answer 4

您需要将方法调用返回的值分配回字符串引用变量。每次执行replaceAll()操作时，它都会返回一个新的String对象，但weatherLocation变量仍在引用原始字符串

  weatherLocation = weatherLocation.replaceAll("how","")
                    .replaceAll("what","")
                    .replaceAll("weather", "")
                    .replaceAll("like", "")
                    .replaceAll(" in", "")
                    .replaceAll(" at", "")
                    .replaceAll("around", "");