java 打印出列表_在java w/o循環中以列表格式打印數組列表。

男娘i 2022-10-23 05:56 104阅读 0赞

I am trying to re-define the method toString(), which has to return a String, to print an array list called cards with type Card. Because toString() has to return a string I can't use a loop to print out each element one by one, yet I want to print the array list in a list format. Basically, does anyone know how to make toString() return the array list cards as a string without using a loop?

我正在嘗試重新定義方法toString()，它必須返回一個字符串，以打印一個名為cardwithtype Card的數組列表。因為toString()必須返回一個字符串，我不能使用循環將每個元素逐個打印出來，但是我想要以列表格式打印數組列表。基本上，有誰知道如何讓toString()將數組列表卡作為字符串返回，而不使用循環嗎?

cards array list definition

卡數組列表定義

ArrayList cards = new ArrayList();

Card class creator

卡類創造者

Card card1 = new Card(String suit, String rank, int value);

toString method

toString方法

public String deckToString()\{

return cards;

What it should print

應該打印

\[suit, rank, value\]

etc.

What it currently prints

目前打印什么

\[suit, rank, value\] \[suit, rank, value\] etc.

2 个解决方案

\#1

If I understand correctly, you want each value on its own line. In other words, join the values by a line break, instead of by comma.

如果我理解正確，您希望每個值都在自己的行上。換句話說，通過換行符來連接這些值，而不是用逗號。

public String deckToString() \{

return String.join("\\n", cards.stream().map(Card::toString).collect(Collectors.toList()));

\#2

public String deckToString()\{

temp="";

for (int i = 0;i

temp+=cards.get(i)+"\\n";

return temp;

This simply iterates through the cards and adds a newline for each card and adds it to the return string. This is similar to janos solution but is more visually simple.

這只是簡單地遍歷卡片並為每張卡片添加一個換行符，並將其添加到返回字符串。這與janos的解決方案類似，但在視覺上更簡單。