概述
本文用AndroidStudio制作一个非常简单的计算器app。目的是熟悉前端设计元素和后端代码执行逻辑,以及二者的整合。
演示
能实现最简单的四则运算:
![](http://images.phyjack.com/calculator_show.gif)
代码
前端:activity_main.xml
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| <?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=".MainActivity" android:background="@color/whole_bg">
<LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical">
<TextView android:layout_width="match_parent" android:layout_height="50dp" android:text="Calculator" android:textSize="35dp" android:gravity="center"></TextView>
<TextView android:id="@+id/tv_display" android:layout_width="match_parent" android:layout_height="90dp" android:text="" android:textSize="60dp" android:background="#C5BEBE" android:layout_margin="5dp" android:gravity="right" ></TextView>
<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical">
<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:weightSum="4" android:padding="10dp"> <Button android:id="@+id/btn_7" android:text="7" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_8" android:text="8" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_9" android:text="9" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_add" android:text="+" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/operator_bg" android:layout_margin="5dp"></Button> </LinearLayout>
<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:weightSum="4" android:padding="10dp"> <Button android:id="@+id/btn_4" android:text="4" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_5" android:text="5" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_6" android:text="6" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_minus" android:text="-" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/operator_bg" android:layout_margin="5dp"></Button> </LinearLayout>
<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:weightSum="4" android:padding="10dp"> <Button android:id="@+id/btn_1" android:text="1" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_2" android:text="2" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_3" android:text="3" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_multiple" android:text="x" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/operator_bg" android:layout_margin="5dp"></Button> </LinearLayout>
<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:weightSum="4" android:padding="10dp"> <Button android:id="@+id/btn_ac" android:text="C" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_0" android:text="0" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_cal" android:text="=" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/button_bg" android:layout_margin="5dp"></Button> <Button android:id="@+id/btn_divide" android:text="/" android:textSize="30dp" android:layout_width="0dp" android:layout_weight="1" android:layout_height="80dp" android:background="@color/operator_bg" android:layout_margin="5dp"></Button> </LinearLayout>
</LinearLayout>
<ImageView android:id="@+id/iv_ad" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/fish" android:layout_margin="5dp" ></ImageView>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
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后端:MainActivity.java
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| package com.example.myproject02;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.TextView; import android.widget.Toast;
public class MainActivity extends AppCompatActivity { TextView tv_display; Button btn_0,btn_1,btn_2,btn_3,btn_4,btn_5,btn_6,btn_7,btn_8,btn_9; Button btn_add,btn_minus,btn_multiple,btn_divide; Button btn_ac, btn_cal; float f_temp1, f_temp2, res; String operator;
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);
f_temp1 = 0.0f; f_temp2 = 0.0f; res = 0.0f; operator = "";
tv_display = findViewById(R.id.tv_display); btn_0 = findViewById(R.id.btn_0); btn_1 = findViewById(R.id.btn_1); btn_2 = findViewById(R.id.btn_2); btn_3 = findViewById(R.id.btn_3); btn_4 = findViewById(R.id.btn_4); btn_5 = findViewById(R.id.btn_5); btn_6 = findViewById(R.id.btn_6); btn_7 = findViewById(R.id.btn_7); btn_8 = findViewById(R.id.btn_8); btn_9 = findViewById(R.id.btn_9); btn_add = findViewById(R.id.btn_add); btn_minus = findViewById(R.id.btn_minus); btn_multiple = findViewById(R.id.btn_multiple); btn_divide = findViewById(R.id.btn_divide); btn_ac = findViewById(R.id.btn_ac); btn_cal = findViewById(R.id.btn_cal);
ClickAddString click_addstr = new ClickAddString(); ClickAdd click_add = new ClickAdd(); ClickMinus click_minus = new ClickMinus(); ClickMultiple click_multip = new ClickMultiple(); ClickDivide click_divide = new ClickDivide(); ClickAc click_ac = new ClickAc(); ClickCal click_cal = new ClickCal(); btn_0.setOnClickListener(click_addstr); btn_1.setOnClickListener(click_addstr); btn_2.setOnClickListener(click_addstr); btn_3.setOnClickListener(click_addstr); btn_4.setOnClickListener(click_addstr); btn_5.setOnClickListener(click_addstr); btn_6.setOnClickListener(click_addstr); btn_7.setOnClickListener(click_addstr); btn_8.setOnClickListener(click_addstr); btn_9.setOnClickListener(click_addstr); btn_add.setOnClickListener(click_add); btn_minus.setOnClickListener(click_minus); btn_multiple.setOnClickListener(click_multip); btn_divide.setOnClickListener(click_divide); btn_ac.setOnClickListener(click_ac); btn_cal.setOnClickListener(click_cal); }
class ClickAddString implements View.OnClickListener { @Override public void onClick(View v) { String str = tv_display.getText().toString(); Button btn_this = (Button) v; str = str + ((Button) v).getText(); tv_display.setText(str); } }
class ClickAdd implements View.OnClickListener{ @Override public void onClick(View v) { String s1 = tv_display.getText().toString(); f_temp1 = Float.parseFloat(s1); operator = "+"; tv_display.setText(""); } }
class ClickMinus implements View.OnClickListener{ @Override public void onClick(View v) { String s1 = tv_display.getText().toString(); f_temp1 = Float.parseFloat(s1); operator = "-"; tv_display.setText(""); } }
class ClickMultiple implements View.OnClickListener{ @Override public void onClick(View v) { String s1 = tv_display.getText().toString(); f_temp1 = Float.parseFloat(s1); operator = "x"; tv_display.setText(""); } }
class ClickDivide implements View.OnClickListener{ @Override public void onClick(View v) { String s1 = tv_display.getText().toString(); f_temp1 = Float.parseFloat(s1); operator = "/"; tv_display.setText(""); } }
class ClickAc implements View.OnClickListener{ @Override public void onClick(View v) { tv_display.setText(""); f_temp1 = 0.0f; f_temp2 = 0.0f; operator = ""; } }
class ClickCal implements View.OnClickListener{ @Override public void onClick(View v) { String s2 = tv_display.getText().toString(); f_temp2 = Float.parseFloat(s2); float res = calculate(); tv_display.setText(Float.toString(res)); } }
float calculate(){ switch(operator){ case "+": res = f_temp1 + f_temp2; break; case "-": res = f_temp1 - f_temp2; break; case "x": res = f_temp1 * f_temp2; break; case "/": res = f_temp1 / f_temp2; break; default: res = -11111111.0f; Toast.makeText(MainActivity.this, "error", Toast.LENGTH_SHORT).show(); } return res; }
}
|
额外定义的颜色:values/colors.xml
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| <?xml version="1.0" encoding="utf-8"?> <resources> <color name="black">#FF000000</color> <color name="white">#FFFFFFFF</color> <color name="whole_bg">#BAF1A6</color> <color name="button_bg">#DB2D9C</color> <color name="operator_bg">#FF5722</color> </resources>
|
AndroidManifest.xml
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| <?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.MyProject02" tools:targetApi="31"> <activity android:name=".MainActivity" android:exported="true"> <intent-filter> <action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application>
</manifest>
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