[Do it! Android] 도전! 2. SMS 입력 화면 만들고 글자 수 표시하기

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:id="@+id/activity_main"
    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="org.androidtown.a2_2.MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/bytenumber"
        android:layout_alignParentTop="true"
        android:layout_margin="15dp"
        android:background="#88000000"
        android:gravity="left|top"
        android:textSize="25dp" />

    <TextView
        android:id="@+id/bytenumber"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/btgroup"
        android:layout_gravity="right"
        android:layout_marginTop="10dp"
        android:gravity="right"
        android:textSize="18dp"/>

    <LinearLayout
        android:id="@+id/btgroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/send"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="전송"/>

        <Button
            android:id="@+id/exit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="닫기" />

    </LinearLayout>
</RelativeLayout>

MainActivity.java

package org.androidtown.a2_2;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.UnsupportedEncodingException;

public class MainActivity extends AppCompatActivity {

    private final int LIMIT = 80;
    private EditText editText;
    private TextView byteLabel;

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

        editText = (EditText)findViewById(R.id.editText);
        byteLabel = (TextView)findViewById(R.id.bytenumber);
        Button send = (Button)findViewById(R.id.send);
        Button exit = (Button)findViewById(R.id.exit);

        editText.addTextChangedListener(new TextWatcher(){
            String beforeText;

            @Override
            public void beforeTextChanged(CharSequence charSequence, int start, int count, int after){
                beforeText = charSequence.toString();
            }

            @Override
            public void onTextChanged(CharSequence charSequence, int start, int before, int count){

            }

            @Override

            public void afterTextChanged(Editable editable){
                int length = showBytes();
                if(length > LIMIT)
                    editText.setText(beforeText);
            }

        });

        send.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                Toast.makeText(getApplicationContext(), "전송되었습니다.", Toast.LENGTH_LONG).show();
            }
        });

        exit.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                MainActivity.this.finish();
            }
        });
        showBytes();
    }
    private int showBytes(){
        try{
            int length = editText.getText().toString().getBytes("EUC-KR").length;
            byteLabel.setText(length + " / 80 바이트");
            return length;
        }catch(UnsupportedEncodingException e){
            e.printStackTrace();
        }
        return -1;
    }
}