键盘事件OnKeyListener

1.效果图：就是在文本框中输入A，则显示A，输入B，则显示B....

(1)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.app3.MainActivity"
     android:orientation="vertical">

     <EditText
         android:id="@+id/et"
         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"
         android:text="" />
 </LinearLayout>

(2)MainAcivity.java

 package com.example.app3;

 import android.content.DialogInterface;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.KeyEvent;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.TextView;

 public class MainActivity extends AppCompatActivity {
     private EditText editText;
     private TextView textView;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         editText = (EditText) findViewById(R.id.et);
         textView = (TextView) findViewById(R.id.tv_show);

         editText.setOnKeyListener(new View.OnKeyListener() {
             @Override
             public boolean onKey(View v, int keyCode, KeyEvent event) {         //注意这里参数的变化
                 switch (event.getKeyCode()){
                     case KeyEvent.KEYCODE_A:
                         textView.setText("点击了A");
                         break;
                     case KeyEvent.KEYCODE_B:
                         textView.setText("点击了B");
                         break;
                     case KeyEvent.KEYCODE_C:
                         textView.setText("点击了C");
                         break;
                 }
                 return false;
             }
         });

     }
 }

2.效果图：实现输入银行卡号，输入一个数，显示一个数，直到输出所有的银行卡号，四位显示一个空格

（1）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.app3.MainActivity"
     android:orientation="vertical">

     <EditText
         android:id="@+id/et"
         android:hint="请输入您的银行卡号"
         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"
         android:text="" />
 </LinearLayout>

(2)MainAcivity.java

 package com.example.app3;

 import android.content.DialogInterface;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.KeyEvent;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.TextView;

 public class MainActivity extends AppCompatActivity {
     private EditText editText;
     private TextView textView;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         editText = (EditText) findViewById(R.id.et);
         textView = (TextView) findViewById(R.id.tv_show);

         editText.setOnKeyListener(new View.OnKeyListener() {
             @Override
             public boolean onKey(View v, int keyCode, KeyEvent event) {
             editText.setOnKeyListener(new View.OnKeyListener() {
                 @Override
                 public boolean onKey(View v, int keyCode, KeyEvent event) {
                     switch (event.getAction()){
                         case KeyEvent.ACTION_UP:
                             String info = editText.getText().toString();
                             textView.setText("您输入的银行卡号是："+subs(info));
                         case  KeyEvent.ACTION_DOWN:
                             break;
                     }
                     return false;
                 }
             });
                 return false;
             }
         });

     }

     public String subs(String info){
         String mess="";
         for(int i =0;i<=info.length()/4;i++){
             if(i*4+4<info.length()){
                 mess=mess+info.substring(i*4,i*4+4)+"  ";
             }else{
                 mess=mess+info.substring(i*4,info.length());
             }
         }
         return mess;
     }
 }