Java 如何连接ArrayList<；字符串>；到另一个字符串？

我有一个包含这些字段的State类

String name;
City capital;
ArrayList<String> neighbors;

我正试图在州里测试这种方法

State ME = new State("ME", augusta, MEneighbors );

奥古斯塔是一座有明确定义的城市，梅内堡是一位具有

MEneighbors.add("NH");

这是我目前的测试

t.checkExpect(ME.toString(),
    "new State(ME, " + augusta.toString() + ", " + [NH] + ")");

我不太明白这为什么不起作用。它一直工作到ArrayList MEneighbors。如何将ArrayList添加为字符串

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非常感谢

定义toString方法时，调用ArrayList的方法，如下所示

public String toString(){
return ("new State(" + 
    this.name  + ", " + 
    this.capital + ", " + 
    this.neighbors.toString() + ")\n");
}

toString

方法

Returns a string representation of this collection. The string representation consists of 
a list of the collection's elements in the order they are returned by its iterator, 
enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", "
(comma and space). Elements are converted to strings as by String.valueOf(Object).

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即使您将代码修复为：

t.checkExpect(ME.toString(),
    "new State(ME, " + augusta.toString() + ", " + "[NH]" + ")");

注：括号内加引号

---

您仍然忘记在右侧添加“\n”！因为您的toString方法最后添加了“\n”

这甚至可以编译吗？它怎么不工作？您得到的输出是否不正确？异常消息？

+[NH]+

这在这个世界上永远不会编译。ArrayList的默认值是吗。toString（）不够？+[NH]+不编译，你想做什么

t.checkExpect(ME.toString(),
    "new State(ME, " + augusta.toString() + ", " + "[NH]" + ")");