添加到ArrayList

Question

我无法弄清楚为什么我不能将项添加到ArrayList.我尝试了几种不同的方式添加项目,但它们不起作用.

class Problem {
public ArrayList<String> problems = new ArrayList<String>();
public ArrayList<String> answers = new ArrayList<String>();

private String question1 = "What is 2+2?";
private String question2 = "What is the square root of 25";
private String question3 = "What is the next number in the sequence? {2, 4, 6}";
private String question4 = "What is 8*8?";



String[] temp1 = {question1, question2, question3, question4};


for (String s : temp1)
    problems.add(s);

}

我也试过了

problems.add(question1);
problems.add(question2);
problems.add(question3);
problems.add(question4);

这也不起作用.

编译器说标识符是预期的.

Answer 1

尝试添加import java.util.ArrayList;到文件的顶部.

您还需要一个main运行方法,其签名如下:

public static void main(String[] args)

此外,如果您不打算更改它们,则应该使字符串常量final(和/或static).

最后,temp1是默认("朋友")可见性.

我假设这是一个代码片段而不是你实际运行的代码片段.