焦点改变事件OnFocusChangeListener

效果图

1.MainActivity.java

 package com.example.app2;

 import android.support.v7.app.AppCompatActivity;

 import android.os.Bundle;

 import android.view.View;

 import android.widget.EditText;

 import android.widget.TextView;

 public class MainActivity extends AppCompatActivity {

     private TextView textView;

     private EditText editText;

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_main);

         textView = (TextView) findViewById(R.id.tv_show);

         editText = (EditText) findViewById(R.id.et_mail1);

         editText.setOnFocusChangeListener(new View.OnFocusChangeListener() {

             @Override

             public void onFocusChange(View v, boolean hasFocus) {

                 String et_info = editText.getText().toString();

                 String reges="\\w+@\\w+(\\.\\w{2,3})*\\.\\w{2,3}";      //正则表达式验证邮箱是否正确

                 if(et_info.matches(reges)){

                     textView.setText("您输入的邮箱是："+et_info+"符合条件");

                 }else{

                     textView.setText("您输入的邮箱是："+et_info+"不符合条件");

                 }

             }

         });

     }

 }

2.activity_main.xml

 <?xml version="1.0" encoding="utf-8"?>

 <LinearLayout 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:paddingBottom="@dimen/activity_vertical_margin"

     android:paddingLeft="@dimen/activity_horizontal_margin"

     android:paddingRight="@dimen/activity_horizontal_margin"

     android:paddingTop="@dimen/activity_vertical_margin"

     tools:context="com.example.app2.MainActivity"

     android:orientation="vertical"

     >

     <TextView

         android:layout_width="wrap_content"

         android:layout_height="wrap_content"

         android:text="请输入您的邮箱" />

     <EditText

         android:id="@+id/et_mail1"

         android:hint="第一个文本输入框"

         android:layout_width="match_parent"

         android:layout_height="wrap_content" />

     <EditText

         android:id="@+id/et_mail2"

         android:hint="第二个文本输入框"

         android:layout_width="match_parent"

         android:layout_height="wrap_content" />

     <TextView

         android:id="@+id/tv_show"

         android:layout_width="wrap_content"

         android:layout_height="wrap_content" />

 </LinearLayout>