Dialog相关学习

---

1.如何在点击确定或取消按钮时，不取消弹窗

使用场景:在弹窗输入参数后，需要对参数进行校验是否合法时。如果不规范则提示用户重新输入

使用AlertDialog.Builder创建的Dialog，在调用setPositiveButton相关的按钮时，会自动隐藏弹窗。若不想隐藏则需要再获取一次Button设置监听事件

public class CustomDialog extends DialogFragment {
    private EditText mUserName;
    private EditText mPassword;
    
    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        LayoutInflater inflater = requireActivity().getLayoutInflater();
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        View view = inflater.inflate(R.layout.custom_dialog, null);
        mUserName = view.findViewById(R.id.username);
        mPassword = view.findViewById(R.id.password);
        builder.setView(view).setPositiveButton("确定", null).setNegativeButton("取消", null);
        AlertDialog dialog = builder.create();
		// 必须调用show方法，否则下面获取到的button为null
        dialog.show();
        dialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener(v -> {
            if (TextUtils.isEmpty(mUserName.getText().toString())) {
                Toast.makeText(getActivity(), "用户名为空", Toast.LENGTH_SHORT).show();
                return;
            } else {
                dialog.dismiss();
            }
        });
        return dialog;
    }
}

2.DialogFragment在显示时提示Theme错误

java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
      at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:696)
      at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
      at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:552)

该问题属于没有给DialogFragment弹窗依赖的Activity没有使用AppCompat的Theme.

---

解决方案：

1. 使用的Activity直接继承Activity而不用继承AppCompatActivity
2. 在AndroidManifest对应的Activity的主题改为使用AppCompat的主题

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>