如何控制 Android 中默认警告框的高度和宽度?
androidapps/applicationsmobile development
此示例演示了如何控制 Android 中默认警告框的高度和宽度。
步骤 1 − 在 Android Studio 中创建一个新项目，前往"文件"->"新建项目"，并填写所有必需信息以创建新项目。
步骤 2 − 将以下代码添加到 res/layout/activity_main.xml。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/relativeLayout" tools:context=".MainActivity"> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Show Alert Dialog" android:layout_centerInParent="true" /> </RelativeLayout>
步骤 3 − 将以下代码添加到 src/MainActivity.java
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.RelativeLayout;
public class MainActivity extends AppCompatActivity{
Button button;
RelativeLayout relativeLayout;
Context context;
Activity myActivity;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
relativeLayout = findViewById(R.id.relativeLayout);
context = getApplicationContext();
button = findViewById(R.id.button);
myActivity = MainActivity.this;
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(myActivity);
builder.setTitle("My Action Bar");
builder.setMessage("This is my custom Action bar, do you like it?");
builder.setPositiveButton("Yes", null);
builder.setNegativeButton("No", null);
AlertDialog alertDialog = builder.create();
alertDialog.show();
WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams();
layoutParams.copyFrom(alertDialog.getWindow().getAttributes());
layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
layoutParams.height = WindowManager.LayoutParams.MATCH_PARENT;
alertDialog.getWindow().setAttributes(layoutParams);
}
});
}
}
步骤 4 − 将以下代码添加到 androidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
让我们尝试运行您的应用程序。假设您已将实际的 Android 移动设备连接到电脑。要从 Android Studio 运行该应用程序，请打开项目的某个活动文件，然后点击工具栏中的 
运行图标。选择您的移动设备作为选项，然后勾选将显示默认屏幕的移动设备。 –
