CARA MEMBUAT KALKULATOR SEDERHANA MENGGUNAKAN ANDROID STUDIO

Halo, kali ini saya akan membahas sedikit tentang penggunaan Android Studio dengan membuat aplikasi kalkulator sederhana. 

Ikuti saja langkah-langkah berikut

Pertama-tama, kita deklarasikan semua komponen dan fungsi layout yang kita gunakan menggunakan code seperti berikut.

package com.almer.alkalkulator;

        import android.support.v7.app.AppCompatActivity;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.Button;
        import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private Button zero;
    private Button one;
    private Button two;
    private Button three;
    private Button four;
    private Button five;
    private Button six;
    private Button seven;
    private Button eight;
    private Button nine;
    private Button add;
    private Button sub;
    private Button mul;
    private Button div;
    private Button equal;
    private Button clear;
    private TextView info;
    private TextView result;
    private final char ADDITION = '+';
    private final char SUBSTRACTION = '-';
    private final char MULTIPLY = '*';
    private final char DIVISION = '/';
    private final char EQU = 0;
    private double val1 = Double.NaN;
    private double val2;
    private char ACTION;


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

        setupUIViews();

        zero.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "0");
            }
        });

        one.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "1");
            }
        });

        two.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "2");
            }
        });

        three.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "3");
            }
        });

        four.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "4");
            }
        });

        five.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "5");
            }
        });

        six.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "6");
            }
        });
        seven.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "7");
            }
        });

        eight.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "8");
            }
        });

        nine.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                info.setText(info.getText().toString() + "9");
            }
        });

        add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                compute();
                ACTION = ADDITION;
                result.setText(String.valueOf(val1) + "+");
                info.setText(null);
            }
        });

        sub.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                compute();
                ACTION = SUBSTRACTION;
                result.setText(String.valueOf(val1) + "-");
                info.setText(null);
            }
        });

        mul.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                compute();
                ACTION = MULTIPLY;
                result.setText(String.valueOf(val1) + "*");
                info.setText(null);
            }
        });

        div.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                compute();
                ACTION = DIVISION;
                result.setText(String.valueOf(val1) + "/");
                info.setText(null);
            }
        });

        equal.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                compute();
                ACTION = EQU;
                result.setText(result.getText().toString() + String.valueOf(val2) + "=" + String.valueOf(val1));
                info.setText(null);
            }
        });

        clear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(info.getText().length() > 0){
                    CharSequence name = info.getText().toString();
                    info.setText(name.subSequence(0, name.length()-1));
                }
                else{
                    val1 = Double.NaN;
                    val2 = Double.NaN;
                    info.setText(null);
                    result.setText(null);
                }
            }
        });
    }

    private void setupUIViews(){

        zero = (Button)findViewById(R.id.btn0);
        one = (Button)findViewById(R.id.btn1);
        two = (Button)findViewById(R.id.btn2);
        three = (Button)findViewById(R.id.btn3);
        four = (Button)findViewById(R.id.btn4);
        five = (Button)findViewById(R.id.btn5);
        six = (Button)findViewById(R.id.btn6);
        seven = (Button)findViewById(R.id.btn7);
        eight = (Button)findViewById(R.id.btn8);
        nine = (Button)findViewById(R.id.btn9);
        add = (Button)findViewById(R.id.btnadd);
        sub = (Button)findViewById(R.id.btnsub);
        mul = (Button)findViewById(R.id.btnmul);
        div = (Button)findViewById(R.id.btndiv);
        equal = (Button)findViewById(R.id.btnequal);
        clear = (Button)findViewById(R.id.btnclr);
        info = (TextView)findViewById(R.id.tvctrl);
        result = (TextView)findViewById(R.id.tvrslt);
    }

    private void compute(){
        if(!Double.isNaN(val1)){
            val2 = Double.parseDouble(info.getText().toString());

            switch(ACTION){
                case ADDITION:
                    val1 = val1 + val2;
                    break;
                case SUBSTRACTION:
                    val1 = val1 - val2;
                    break;
                case MULTIPLY:
                    val1 = val1 * val2;
                    break;
                case DIVISION:
                    val1 = val1 / val2;
                    break;
                case EQU:
                    break;
            }
        }
        else{
            val1 = Double.parseDouble(info.getText().toString());
        }
    }
}

lalu buat kodingan .xml seperti code dibawah ini :

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="com.almer.alkalkulator.MainActivity">

<Button
    android:id="@+id/btn9"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/btn4"
    android:layout_alignStart="@+id/tvctrl"
    android:text="9" />

<Button
    android:id="@+id/btn8"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/btn9"
    android:layout_toEndOf="@+id/btn9"
    android:text="8"
    tools:text="8" />

<Button
    android:id="@+id/btn7"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/btn9"
    android:layout_toEndOf="@+id/btn8"
    android:text="7"
    tools:text="7" />

<Button
    android:id="@+id/btn6"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/btn3"
    android:layout_alignStart="@+id/btn9"
    android:text="6"
    tools:text="6" />

<Button
    android:id="@+id/btn5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/btn6"
    android:layout_toEndOf="@+id/btn9"
    android:text="5" />

<Button
    android:id="@+id/btn4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/btn7"
    android:layout_alignTop="@+id/btn6"
    android:text="4"
    tools:text="4" />

<Button
    android:id="@+id/btn3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/btnclr"
    android:layout_alignStart="@+id/btn9"
    android:text="3" />

<Button
    android:id="@+id/btn2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/btn3"
    android:layout_toEndOf="@+id/btn9"
    android:text="2" />

<Button
    android:id="@+id/btn1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/btn7"
    android:layout_alignTop="@+id/btn3"
    android:text="1" />

<Button
    android:id="@+id/btnclr"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignStart="@+id/btn9"
    android:layout_marginBottom="52dp"
    android:text="CLR" />

<Button
    android:id="@+id/btn0"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/btnclr"
    android:layout_toEndOf="@+id/btn9"
    android:text="0" />

<Button
    android:id="@+id/btnequal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/btnclr"
    android:layout_alignStart="@+id/btn7"
    android:text="=" />

<Button
    android:id="@+id/btndiv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentEnd="true"
    android:layout_alignTop="@+id/btn9"
    android:layout_marginEnd="11dp"
    android:text="/" />

<Button
    android:id="@+id/btnmul"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/btndiv"
    android:layout_alignTop="@+id/btn6"
    android:text="*" />

<Button
    android:id="@+id/btnadd"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/btndiv"
    android:layout_alignTop="@+id/btn3"
    android:text="+" />

<Button
    android:id="@+id/btnsub"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/btndiv"
    android:layout_alignTop="@+id/btn0"
    android:text="-" />

<TextView
    android:id="@+id/tvctrl"
    android:layout_width="match_parent"
    android:layout_height="56dp"
    android:layout_alignParentEnd="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="200dp" />

<TextView
    android:id="@+id/tvrslt"
    android:layout_width="match_parent"
    android:layout_height="57dp"
    android:layout_alignParentEnd="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="132dp" />

</RelativeLayout>


Ini adalah hasil compilenya :

Seperti itulah penjelasan singkat mengenai cara membuat aplikasi kalkulator sederhana dengan menggunakan Android Studio. Semoga bermanfaat!