java - 如何从 ArrayList 获取值

Question

如何从 ArrayList<String[]> 获取或打印字符串？

ArrayList<String[]> arrayList = new ArrayList<>();
arrayList.add(new String[]{"A1","A1","A3"});
arrayList.add(new String[]{"B1","B1","B3"});
arrayList.add(new String[]{"C1","C1","C3"});

System.out.println("*** 1 ***");
System.out.println(arrayList);

System.out.println("*** 2 ***");
for (int i = 0; i < arrayList.size(); i++) {
    System.out.println((String[])arrayList.get(i));
}

System.out.println("*** 3 ***");
for (int i = 0; i < arrayList.size(); i++) {
    System.out.println(arrayList.get(i).toString());
}

System.out.println("*** 4 ***");
for (int i = 0; i < arrayList.size(); i++) {
    String[] strings = arrayList.get(i);
    System.out.println(strings);
}

输出:

*** 1 ***
[[Ljava.lang.String;@2a85f3d6, [Ljava.lang.String;@404b7c69, [Ljava.lang.String;@1bd4f279]

*** 2 ***
[Ljava.lang.String;@2a85f3d6
[Ljava.lang.String;@404b7c69
[Ljava.lang.String;@1bd4f279
*** 3 ***
[Ljava.lang.String;@2a85f3d6
[Ljava.lang.String;@404b7c69
[Ljava.lang.String;@1bd4f279
*** 4 ***
[Ljava.lang.String;@2a85f3d6
[Ljava.lang.String;@404b7c69
[Ljava.lang.String;@1bd4f279

Answer 1

遗憾的是，java 对于数组的默认 toString() 是无用的。您必须使用实用程序方法 Arrays.toString() 。这将起作用:

for (String[] strings : arrayList)
    System.out.println(Arrays.toString(strings));