java - Android：在 DialogInterface.OnClickListener() 中的 int 为 -1

Question

我不明白为什么会这样。我有以下代码：

AlertDialog.Builder builder = new AlertDialog.Builder(SettingsActivityNew.this);

builder.setTitle("Title");
builder.setSingleChoiceItems(R.array.example_arrays, 1, null);              
builder.setNegativeButton("Cancel", null);
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int which) {
        Toast.makeText(SettingsActivityNew.this, "which: " + which, Toast.LENGTH_LONG).show();
    }
});
builder.show();

出于某种奇怪的原因，int which 一直给我-1。为什么会这样？

Answer 1

从文档：

Parameters
dialog  The dialog that received the click.
which   The button that was clicked (e.g. BUTTON1) or the position of the item clicked.

---

BUTTON_POSITIVE ：

public static final int BUTTON_POSITIVE

Added in API level 3
The identifier for the positive button.

Constant Value: -1 (0xffffffff)

所以这并不奇怪，但完全正常。你每次都得到-1，因为你点击了positiveButton你的对话框:)