Membuat aplikasi kalkulator balok
hello temen2,
yuk kita buat aplikasi sederhana..
yaitu aplikasi menghitung balok..
1. langkah pertama, kita buat layoutnya...
<?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:padding="16dp"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/length"/>
<EditText
android:id="@+id/edt_length"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal"
android:lines="1"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/width"/>
<EditText
android:id="@+id/edt_width"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal"
android:lines="1"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/height"/>
<EditText
android:id="@+id/edt_height"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal"
android:lines="1"/>
<Button
android:id="@+id/btn_calculate"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/calculate"/>
<TextView
android:id="@+id/tv_result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="@string/result"
android:textSize="24sp"
android:textStyle="bold"/>
</LinearLayout>
2. langkah kedua, kita buat folder stringnya..
res > value > string
<resources>
<string name="app_name">VolumeBalok</string>
<string name="length">Panjang</string>
<string name="width">Lebar</string>
<string name="height">Tinggi</string>
<string name="calculate">Hitung</string>
<string name="result">Hasil</string>
</resources>
ini akan otomatis ada bila sudah kita konfigurasikan...
3. langkah ketiga, kita atur di bagian main activitynya
package com.example.volumebalok;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private EditText edtWidth, edtHeight, edtLength;
private Button btnCalculate;
private TextView tvResult;
private static final String STATE_RESULT = "state_result";
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString(STATE_RESULT, tvResult.getText().toString());
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edtWidth = findViewById(R.id.edt_width);
edtHeight = findViewById(R.id.edt_height);
edtLength = findViewById(R.id.edt_length);
btnCalculate = findViewById(R.id.btn_calculate);
tvResult = findViewById(R.id.tv_result);
btnCalculate.setOnClickListener(this);
if (savedInstanceState != null){
String result = savedInstanceState.getString(STATE_RESULT);
tvResult.setText(result);
}
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.btn_calculate){
String inputLength = edtLength.getText().toString().trim();
String inputWidth = edtWidth.getText().toString().trim();
String inputHeight = edtHeight.getText().toString().trim();
boolean isEmptyFields = false;
boolean isInvalidDouble = false;
if (TextUtils.isEmpty(inputLength)){
isEmptyFields = true;
edtLength.setError("Field ini tidak boleh kosong");
}
if (TextUtils.isEmpty(inputWidth)){
isEmptyFields = true;
edtWidth.setError("Field ini tidak boleh kosong");
}
if (TextUtils.isEmpty(inputHeight)){
isEmptyFields = true;
edtHeight.setError("Field ini tidak boleh kosong");
}
Double length = toDouble(inputLength);
Double width = toDouble(inputWidth);
Double height = toDouble(inputHeight);
if (length == null){
isInvalidDouble = true;
edtLength.setError("Field ini harus berupa nomer");
}
if (width == null){
isInvalidDouble = true;
edtWidth.setError("Field ini harus berupa nomer");
}
if (height == null){
isInvalidDouble = true;
edtHeight.setError("Field ini harus berupa nomer");
}
if (!isEmptyFields && !isInvalidDouble){
double volume = length * width * height;
tvResult.setText(String.valueOf(volume));
}
}
}
private Double toDouble(String str) {
try {
return Double.valueOf(str);
} catch (NumberFormatException e){
return null;
}
}
}
bila sudah, maka akan tampil aplikasi seperti dibawah,
tampilan aplikasi kita bila sudah jadi...
selamat mencoba...
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