在自定义 ArrayList Java 中创建 toString 方法

Question

我正在创建自己的ArrayList并停留在toString()方法中，你能帮我在打印最后一项后摆脱逗号吗？

toString()方法：

    @Override
    public String toString() {  
    StringBuilder sb = new StringBuilder();
    if(store == null) {
        return "[]";
    } else {

    for (int i = 0; i < size; i++) {
        sb.append(store[i].toString() + ", ");
    }

    return "[" + sb.toString() + "]";
    }
}

Main方法：

public static void main(String[] args) {
    MyArrayList<String> fruits = new MyArrayList<>();

    System.out.println("My array list with fruits :)");

    fruits.add("Bananas");
    fruits.add("Apples");
    fruits.add("Pineapple");
    fruits.add("Peaches");
    fruits.add("Pears");
    fruits.add("Plum");

    System.out.println("The list of fruits : " + fruits);

    fruits.clear();

    System.out.println("All fruits have been eaten =) " + fruits);

输出：

[Bananas, Apples, Pineapple, Peaches, Pears, Plum, ]

Answer 1

在字符串的开头连接逗号并在索引 1 处开始循环

if(store.length > 0) {
   sb.append(store[0].toString());
}

for (int i = 1; i < store.length; i++) {
   sb.append(", " + store[i].toString());
}

Answer 2

只需添加一个 if 条件以仅在索引i不等于for循环接受的最后一个索引时添加逗号

@Override
    public String toString() {  
    StringBuilder sb = new StringBuilder();
    if(store == null) {
        return "[]";
    } else {

    for (int i = 0; i < size; i++) {
        sb.append(store[i].toString());
        if(i != size - 1) sb.append(",");
    }

    return "[" + sb.toString() + "]";
    }
}