[Java] android studio를 이용하여 별찍기

MainActivity3.java

package kr.or.aiai.app;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity3 extends AppCompatActivity {
    EditText etFirst;
    EditText etLast;
    TextView tvDisp;
    Button btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);

        etFirst = findViewById(R.id.etFirst);
        etLast = findViewById(R.id.etLast);
        tvDisp = findViewById(R.id.tvDisp);
        btn = findViewById(R.id.btn);

        btn.setOnClickListener(view -> {
            myclick();
        });
    }

    public void myclick(){

        String first = etFirst.getText().toString();
        int a = Integer.parseInt(first);
        String last =  etLast.getText().toString();
        int b = Integer.parseInt(last);

        String result = "";
        for(int i=a; i<=b; i++){
            for(int j=0; j<i; j++) {
                result += "*";
            }
            result += "\n";
        }
        tvDisp.setText(result);
    }
}

activity_main3

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity3">

    <LinearLayout
        android:layout_width="409dp"
        android:layout_height="729dp"
        android:orientation="vertical"
        tools:layout_editor_absoluteX="1dp"
        tools:layout_editor_absoluteY="1dp"
        tools:ignore="MissingConstraints">


        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/tvFirst"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:text="첫번째별수:"
                android:textSize="30dp" />

            <EditText
                android:id="@+id/etFirst"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:ems="10"
                android:inputType="text" />

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/tvLast"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:text="마지막별수:"
                android:textSize="30dp" />

            <EditText
                android:id="@+id/etLast"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:ems="10"
                android:inputType="text" />

        </LinearLayout>



        <Button
            android:id="@+id/btn"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="출력하기" />

        <TextView
            android:id="@+id/tvDisp"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="__" />


    </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyApp"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="false">
            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
        <activity
            android:name=".MainActivity3"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

</manifest>

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