1

当我运行此代码时，我收到异常：无法启动活动 ComponentInfo...AdminSettingsActivity：Java.lang.NullPointerExcepiton。任何人都知道，什么会导致这个问题/异常？我有以下代码：

import android.app.AlertDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.preference.PreferenceActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;

public class AdminSettingsActivity extends PreferenceActivity {

private Dialog dialog;
Button btn_ok;
Button btn_cancel;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.admin_preferences);

    showPasswordDialog();
}

private void showPasswordDialog() {
    // create dialog

    dialog = new Dialog(this);

    dialog.setContentView(R.layout.password_dialog);
    dialog.setTitle("Type password...");



    btn_ok = (Button) findViewById(R.id.btn_ok_pass_dialog);

    btn_ok.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            dialog.dismiss();
            Log.d("", "dismis");
        }
    });
    /*
    btn_cancel = (Button) findViewById(R.id.btn_cancel_pass_dialog);
    btn_cancel.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            dialog.dismiss();
            Log.d("", "ok");
        }
    });
    */
    dialog.show();

}
}

并且有 admin_preference.xml：

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

<Preference android:title="title_web_page" >
    <intent android:action="cz.example.k2.PASSWORD_DIALOG" />
</Preference>

</PreferenceScreen>

和password_dialog.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<EditText
    android:id="@+id/edit_text_pass_dialog"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="textPassword" />

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal" >

    <Button
        android:id="@+id/btn_cancel_pass_dialog"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Zrušit" />

    <Button
        android:id="@+id/btn_ok_pass_dialog"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="OK" />
</LinearLayout>

</LinearLayout>

清单.xml：

...
    <activity
        android:name="cz.example.k2.AdminSettingsActivity"
        android:label="@string/admin_settings_activity_label" >
        <intent-filter>
            <action android:name="cz.example.k2.ADMIN_SETTINGS" />

            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>
...
4

1 回答 1

0

我的猜测是错误就在这里，您试图从主布局而不是对话框布局中获取按钮：

btn_ok = (Button) findViewById(R.id.btn_ok_pass_dialog);

你应该膨胀你的对话框布局，然后从中获取按钮

LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.password_dialog, null);
dialog.setContentView(view);
btn_ok = (Button) view.findViewById(R.id.btn_ok_pass_dialog);
于 2013-01-02T10:48:09.367 回答