[Java] DataBinding + LiveData + BindingAdapter

DataBinding  +  LiveData  +  BindingAdapter

---

build.gradle (Module: app)

android {
    dataBinding {
        enabled = true
    }
}

 

 

 

 

 

 

 

 

BindingAdapters.java

package com.jwsoft.javaproject;

import android.view.View;

import androidx.annotation.ColorInt;
import androidx.databinding.BindingAdapter;

public class BindingAdapters {

    @BindingAdapter("android:visibleJW")
    public static void setVisible(View view, Boolean bool) {
        if (bool) view.setVisibility(View.VISIBLE);
        else view.setVisibility(View.INVISIBLE);
    }

    @BindingAdapter("android:colorJW")
    public static void setColor(View view, @ColorInt int color) {
        view.setBackgroundColor(color);
    }

}

코틀린은 build.gradle (Module: app) 안에 

apply plugin: 'kotlin-kapt' 추가해야

@BindingAdapter 어노테이션 사용 가능

 

 

 

 

 

 

 

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>
    <data>
        <variable
            name="mainActivity"
            type="com.jwsoft.javaproject.MainActivity" />
    </data>

    <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:gravity="center"
        android:orientation="vertical"
        android:colorJW="@{mainActivity.liveColor}"
        tools:context=".MainActivity">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="혀가 길지 않은 개발자\nJames Kim"
            android:textSize="30dp"
            android:textStyle="bold"
            android:textAlignment="center"
            android:visibleJW="@{mainActivity.liveVisible}"
            />

        <Button
            android:id="@+id/btnVisible"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:textAllCaps="false"
            android:text="Visible"
            android:textSize="40dp"
            android:textStyle="italic|bold"
            android:layout_marginTop="30dp" />

        <Button
            android:id="@+id/btnInvisible"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:textAllCaps="false"
            android:text="Invisible"
            android:textSize="40dp"
            android:textStyle="italic|bold" />

        <Button
            android:id="@+id/btnChange"
            android:layout_width="300dp"
            android:layout_height="wrap_content"
            android:textAllCaps="false"
            android:text="Change Background Color"
            android:textSize="20dp"
            android:textStyle="italic|bold"
            android:layout_marginTop="100dp"/>

    </LinearLayout>

</layout>

activity_main.xml

 

 

 

 

 

 

MainActivity.java

package com.jwsoft.javaproject;

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;
import androidx.lifecycle.MutableLiveData;

import android.graphics.Color;
import android.os.Bundle;
import android.view.View;

import com.jwsoft.javaproject.databinding.ActivityMainBinding;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    private ActivityMainBinding binding;
    public MutableLiveData<Boolean> liveVisible = new MutableLiveData<>();
    public MutableLiveData<Integer> liveColor = new MutableLiveData<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setMainActivity(this);
        binding.setLifecycleOwner(this);

        binding.btnVisible.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                liveVisible.setValue(true);
            }
        });

        binding.btnInvisible.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                liveVisible.setValue(false);
            }
        });

        binding.btnChange.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int r = new Random().nextInt(256);
                int g = new Random().nextInt(256);
                int b = new Random().nextInt(256);
                liveColor.setValue(Color.argb(255, r, g, b));
            }
        });
    }

}

에러 발생

liveVisible 변수가 null 값이라 에러 발생.

코틀린은 초기화 안 해도 BindingAdapter에 자동으로 false 값 넘어감.

 

 

 

 

 

 

 

MainActivity.java

package com.jwsoft.javaproject;

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;
import androidx.lifecycle.MutableLiveData;

import android.graphics.Color;
import android.os.Bundle;
import android.view.View;

import com.jwsoft.javaproject.databinding.ActivityMainBinding;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    private ActivityMainBinding binding;
    public MutableLiveData<Boolean> liveVisible = new MutableLiveData<>();
    public MutableLiveData<Integer> liveColor = new MutableLiveData<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setMainActivity(this);
        binding.setLifecycleOwner(this);

        liveVisible.setValue(false);        // 초기화 안 해주면 에러 발생.

        binding.btnVisible.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                liveVisible.setValue(true);
            }
        });

        binding.btnInvisible.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                liveVisible.setValue(false);
            }
        });

        binding.btnChange.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int r = new Random().nextInt(256);
                int g = new Random().nextInt(256);
                int b = new Random().nextInt(256);
                liveColor.setValue(Color.argb(255, r, g, b));
            }
        });
    }

}

실행 결과

 

 

 

 

색상 랜덤 추출 참고

stackoverflow.com/questions/5280367/android-generate-random-color-on-click

Android: Generate random color on click?