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>