java – 使用Streams映射到2d数组
发布时间:2020-12-15 08:26:32 所属栏目:Java 来源:网络整理
导读:我正在尝试使用Streams创建一个2d的String数组: String[] fruit1DArray;String[][] fruit2DArray;MapString,String fruitMap = new HashMap();fruitMap.put("apple","red");fruitMap.put("pear","green");fruitMap.put("orange","orange");fruit1DArray = f
我正在尝试使用Streams创建一个2d的String数组:
String[] fruit1DArray; String[][] fruit2DArray; Map<String,String> fruitMap = new HashMap<>(); fruitMap.put("apple","red"); fruitMap.put("pear","green"); fruitMap.put("orange","orange"); fruit1DArray = fruitMap.entrySet() .stream() .map(key -> key.getKey()) .toArray(size -> new String[size]); fruit2DArray = fruitMap.entrySet() .stream() .map(entry-> new String[]{entry.getKey()}) .toArray(size -> new String[size][1]); System.out.println(Arrays.deepToString(fruit1DArray)); System.out.println(Arrays.deepToString(fruit2DArray)); 输出是: [orange,apple,pear] [[orange],[apple],[pear]] 我之后的输出是: [orange,pear] [[orange,orange],[apple,red],[pear,green]] 我指的是https://stackoverflow.com/a/47397601/887235 解决方法
您忘记从输入Map中获取值:
fruit2DArray = fruitMap.entrySet() .stream() .map(e -> new String[]{e.getKey(),e.getValue()}) .toArray(String[][]::new); 输出: [[orange,green]] (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |