[java] 로또 랜덤 숫자 뽑기

 

미리보기

▷ 숫자만들기 버튼을 클릭하면 1부터 45 사이의 랜덤한 숫자가 나오게 하기

 

 

▽ 레이아웃.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/output1"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_marginTop="224dp"
        android:background="@drawable/circle"
        android:gravity="center"
        android:text="1"
        android:textSize="34sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="숫자만들기"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.499" />
</androidx.constraintlayout.widget.ConstraintLayout>

 

 

▽ MainActivity.java

package com.example.test4;

import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.TextView;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

public class MainActivity extends AppCompatActivity {

    TextView output1;

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

    void init() {
        output1 = findViewById(R.id.output1);

        Button btn = findViewById(R.id.button);
        btn.setOnClickListener(v -> {
            makeNumbers();
        });
    } //init()

    void makeNumbers() {
        double num1 = Math.random();
        double num2 = Math.ceil(num1 * 45);
        int num3 = new Double(num2).intValue();
//        Log.d("Main", "Maked Num: " + num1);
//        Log.d("Main", "Maked Num: " + num2);
//        Log.d("Main", "Maked Num: " + num3);
        output1.setText("" + num3);
    } //makeNumbers()

} //Main