activity_main.xml 코드
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
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"
android:orientation="vertical"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="30dp"
android:text="난수 :"
android:gravity="center">
</TextView>
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="난수 생성"
android:textSize="30dp"
android:onClick="makeRandom">
</Button>
</LinearLayout>
MainActivity.JAVA 코드
package com.example.random_num;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
private TextView tv; // 수정
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = findViewById(R.id.textView); // 수정
}
public void makeRandom(View v) {
Random rn = new Random();
int num = rn.nextInt(100)+1;
tv.setText("난수 : " + num);
}
}