[JAVA] Beginners try using android studio Part 2 (event processing)

Event processing with android app

Next, let's make a simple event processing application with android studio. See below for the Hello World app.

Beginners try using android studio Part 1 (Hello World)

launch android studio

First, start android studio and create a new project with ** Empty Activity **.

Operation screen

The operation result looks like this. Enter characters in the input field and press the send button to display the characters in the output field.

Event side coding

Describes the operation when the button is pressed.

MainActivity.java

package com.example.personal.sample_1_event;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    //object
    private Button   btnSend;
    private TextView textInput;
    private TextView textOutput;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //Layout loading
        setContentView(R.layout.activity_main);

        //Object acquisition
        btnSend    = findViewById(R.id.btnSend);
        textInput  = findViewById(R.id.textInput);
        textOutput = findViewById(R.id.textOutput);

        /////////////////////////////////////////////////////////////////////
        //Listener
        /////////////////////////////////////////////////////////////////////

        //button
        btnSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                //Get text
                //CharSequence text = textInput.getText();
                String text = textInput.getText().toString();

                //Text settings
                textOutput.setText(text);
            }
        });

    }

}

Coding of strings used on the screen

Register the character strings used on the screen in ** strings.xml **. Instead of writing the string directly on the screen, enter variables such as textBtnSend.

strings.xml

<resources>
    <string name="app_name">Sample_1_event</string>

    <!--Postscript-->
    <string name="textBtnSend"        >Send</string>
    <string name="textTextLabelInput" >input</string>
    <string name="textTextLabelOutput">output</string>
    <string name="textTextInput"      >Input</string>
    <string name="textTextOutput"     >Output</string>

</resources>

Screen-side coding

** Basically, I don't code directly (I think). ** ** Place parts such as text fields and buttons by dragging and dropping. The screen after placement looks like this.

How to arrange parts

1. 1. Select a button etc.
2. Place it on the screen by dragging and dropping.
3. 3. Select the placed part
4. Enter the ID at the top right of the screen (unique)
5. Press the + button at the position below the ID to determine the reference position. → Here, the left wall and upper wall are used as the standard.
6. In TextView-> text, enter the variable registered in strings.xml.

For the time being, I will also post the sauce.

activity_main.xml

<?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=".MainActivity"
    tools:layout_editor_absoluteY="81dp">

    <Button
        android:id="@+id/btnSend"
        android:layout_width="@dimen/btnSendWidth"
        android:layout_height="@dimen/btnSendHeight"
        android:layout_marginLeft="40dp"
        android:layout_marginStart="40dp"
        android:layout_marginTop="45dp"
        android:text="@string/textBtnSend"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textOutput" />

    <TextView
        android:id="@+id/textLabelInput"
        android:layout_width="40dp"
        android:layout_height="20dp"
        android:layout_marginLeft="40dp"
        android:layout_marginStart="40dp"
        android:layout_marginTop="50dp"
        android:text="@string/textTextLabelInput"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textLabelOutput"
        android:layout_width="40dp"
        android:layout_height="20dp"
        android:layout_marginLeft="40dp"
        android:layout_marginStart="40dp"
        android:layout_marginTop="40dp"
        android:text="@string/textTextLabelOutput"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textLabelInput" />

    <EditText
        android:id="@+id/textInput"
        android:layout_width="150dp"
        android:layout_height="40dp"
        android:layout_marginLeft="20dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="40dp"
        android:ems="10"
        android:hint="@string/textTextInput"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textLabelInput"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/textOutput"
        android:layout_width="150dp"
        android:layout_height="40dp"
        android:layout_marginLeft="20dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:ems="10"
        android:hint="@string/textTextOutput"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textLabelOutput"
        app:layout_constraintTop_toBottomOf="@+id/textInput" />

</android.support.constraint.ConstraintLayout>