Fichier MainColorActivity.java

package com.example.organisation;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import androidx.appcompat.app.AppCompatActivity;

public class MainColorActivity extends AppCompatActivity {
    private View selectedView;

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

        findViewById(R.id.blueBox).setOnClickListener(v -> openColorPicker(v));
        findViewById(R.id.greenBox).setOnClickListener(v -> openColorPicker(v));
    }

    private void openColorPicker(View view) {
        selectedView = view;
        Intent intent = new Intent(this, ColorPickerActivity.class);
        startActivityForResult(intent, 1);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == 1 && resultCode == RESULT_OK && data != null) {
            int color = data.getIntExtra("selectedColor", 0);
            selectedView.setBackgroundColor(color);
        }
    }
}

Fichier ColorPickerActivity.java

package com.example.organisation;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import androidx.appcompat.app.AppCompatActivity;

public class ColorPickerActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_color_picker);
    }

    public void selectColor(View view) {
        int color = ((View) view).getSolidColor();
        Intent intent = new Intent();
        intent.putExtra("selectedColor", color);
        setResult(Activity.RESULT_OK, intent);
        finish();
    }
}

Fichier activity_main_color.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dp">

    <View
        android:id="@+id/blueBox"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:background="#33B5E5"
        android:onClick="openColorPicker"/>

    <View
        android:id="@+id/greenBox"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:background="#99CC00"
        android:onClick="openColorPicker"/>
</LinearLayout>

Fichier activity_color_picker.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:padding="20dp">

    <View
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:background="#FF0000"
        android:onClick="selectColor"/>

    <View
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:background="#00FF00"
        android:onClick="selectColor"/>

    <View
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:background="#0000FF"
        android:onClick="selectColor"/>
</LinearLayout>