Java 8.将Object []转换为String [] [] [英] Java 8. Casting Object[] to String[][]

问题描述

我正在尝试将文件中的数据加载到JTable中。因此，使用Java 8流可以很容易地将文件加载到字符串数组中：

I'm trying to load data from file into JTable. So, using Java 8 streams it is very easy to load file into array of strings:

BufferedReader br = new BufferedReader(new FileReader(f));
Object[] data = br.lines().map((s)->{
            String[] res = {s,"1"}; // Here's some conversion of line into String[] - elements of one row
            return res;
        }).toArray();
TableModel m = new DefaultTableModel( (String[][])data, cols);

但最后一行导致错误：线程AWT-EventQueue-0中的异常java.lang .ClassCastException：[Ljava.lang.Object;无法转换为[[Ljava.lang.Object。
如何将数据转换为String [] []？

But the last line results in error: Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [[Ljava.lang.Object. How can I cast data to String[][]?

推荐答案

如果使用 指定者（字符串[] [] :: new） 而不是 toArray（）它将返回 String [] [] 而不是 Object [] ，你根本不需要把它强制转换（如果你把它分配给 String [ ] [] ）。

If you use toArray(String[][]::new) instead of toArray() it will return a String[][] instead of an Object[] and you wont need to cast it at all (if you assign it to a String[][]).

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