Java流如何在List的嵌套List中添加值

Question

我有一个 List<List<Object>>类型数据。我需要在 List 列表中添加相同的值。我尝试了以下但它不起作用，因为它的类型是 List<Boolean> .

List<List<Object>> data = ...;
data.stream().map(v -> v.add("test")).collect(Collectors.toList());

我怎样才能得到相同类型的 List<List<Object>> ？

我有以下数据:

"data": [
        [
            5,
            "Johnny",
            "Lollobrigida"                
        ],
        [
            6,
            "Bette",
            "Nicholson"               
        ],
        [
            7,
            "Grace",
            "Mostel"                
        ],
        [
            8,
            "Matthew",
            "Johansson"                
        ]
     ]

我想把它改成:

"data": [
        [
            5,
            "Johnny",
            "Lollobrigida",
            "test"
        ],
        [
            6,
            "Bette",
            "Nicholson",
            "test"               
        ],
        [
            7,
            "Grace",
            "Mostel" ,
            "test"               
        ],
        [
            8,
            "Matthew",
            "Johansson",
            "test"                
        ]
     ]

Answer 1

@Boris the Spider 是对的:使用 forEach :

data.forEach(v -> v.add("test"));