android警告对话框示例

本文概述

• Android AlertDialog示例

Android AlertDialog可用于通过“确定”和“取消”按钮显示对话框消息。它可用于打扰并询问用户有关他/她选择继续还是终止的信息。

Android AlertDialog由三个区域组成：标题，内容区域和操作按钮。

Android AlertDialog是Dialog类的子类。

AlertDialog类的方法

Android AlertDialog示例

让我们来看一个简单的android警报对话框示例。

activity_main.xml

你可以有多个组件，这里我们只有一个textview。

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="example.srcmini02.com.alertdialog.MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:text="Close app"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

strings.xml

（可选）你可以将对话框消息和标题存储在strings.xml文件中。

<resources>
    <string name="app_name">AlertDialog</string>
    <string name="dialog_message">Welcome to Alert Dialog</string>
    <string name="dialog_title">srcmini Alert Dialog</string>
</resources>

活动类

让我们编写代码来创建和显示AlertDialog。

package example.srcmini02.com.alertdialog;

import android.content.DialogInterface;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.app.AlertDialog;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    Button closeButton;
    AlertDialog.Builder builder;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        closeButton = (Button) findViewById(R.id.button);
        builder = new AlertDialog.Builder(this);
        closeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                //Uncomment the below code to Set the message and title from the strings.xml file
                builder.setMessage(R.string.dialog_message) .setTitle(R.string.dialog_title);

                //Setting message manually and performing action on button click
                builder.setMessage("Do you want to close this application ?")
                        .setCancelable(false)
                        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                finish();
                                Toast.makeText(getApplicationContext(), "you choose yes action for alertbox", Toast.LENGTH_SHORT).show();
                            }
                        })
                        .setNegativeButton("No", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                //  Action for 'NO' Button
                                dialog.cancel();
                                Toast.makeText(getApplicationContext(), "you choose no action for alertbox", Toast.LENGTH_SHORT).show();
                            }
                        });
                //Creating dialog box
                AlertDialog alert = builder.create();
                //Setting the title manually
                alert.setTitle("AlertDialogExample");
                alert.show();
            }
        });
    }
}

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