1. Not much to say, directly to the renderings
Simple operations such as addition, subtraction, multiplication and division, square, reciprocal, and square root can be performed
2. Java code
package com.example.onlinestudyhelper.activity;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import com.example.onlinestudyhelper.R;
public class CalculatorActivity extends AppCompatActivity implements View.OnClickListener{
private TextView tv_result;
private String firstNum = "";
private String operator = "";
private String secondNum = "";
//当前计算结果
private String result = "";
//显示文本内容
private String showText = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calculator);
tv_result = findViewById(R.id.tv_result);
//为每个按钮控件设置点击监听
findViewById(R.id.btn_cancel).setOnClickListener(this);
findViewById(R.id.btn_divide).setOnClickListener(this);
findViewById(R.id.btn_multiply).setOnClickListener(this);
findViewById(R.id.btn_clear).setOnClickListener(this);
findViewById(R.id.btn_seven).setOnClickListener(this);
findViewById(R.id.btn_eight).setOnClickListener(this);
findViewById(R.id.btn_nine).setOnClickListener(this);
findViewById(R.id.btn_plus).setOnClickListener(this);
findViewById(R.id.btn_four).setOnClickListener(this);
findViewById(R.id.btn_five).setOnClickListener(this);
findViewById(R.id.btn_six).setOnClickListener(this);
findViewById(R.id.btn_minus).setOnClickListener(this);
findViewById(R.id.btn_one).setOnClickListener(this);
findViewById(R.id.btn_two).setOnClickListener(this);
findViewById(R.id.btn_three).setOnClickListener(this);
findViewById(R.id.btn_sqrt).setOnClickListener(this);
findViewById(R.id.btn_1_x).setOnClickListener(this);
findViewById(R.id.btn_zero).setOnClickListener(this);
findViewById(R.id.btn_dot).setOnClickListener(this);
findViewById(R.id.btn_equal).setOnClickListener(this);
}
@Override
public void onClick(View view){
//得到内容
String inputText;
inputText = ((TextView) view).getText().toString();
switch (view.getId()){
case R.id.btn_clear:
clear();
break;
case R.id.btn_cancel:
double pf_result = Double.parseDouble(firstNum) *Double.parseDouble(firstNum);
refreshOperate(String.valueOf(pf_result));
refreshText(showText + "²=" +result);
break;
case R.id.btn_plus:
case R.id.btn_minus:
case R.id.btn_multiply:
case R.id.btn_divide:
operator = inputText;
refreshText(showText+operator);
break;
case R.id.btn_equal:
double caculate_result = caculateFour();
refreshOperate(String.valueOf(caculate_result));
refreshText(showText + "=" +result);
break;
case R.id.btn_sqrt:
double sqrt_result = Math.sqrt(Double.parseDouble(firstNum));
refreshOperate(String.valueOf(sqrt_result));
refreshText(showText + "√=" +result);
break;
case R.id.btn_1_x:
double reciprocal_result = 1.0 / Double.parseDouble(firstNum);
refreshOperate(String.valueOf(reciprocal_result));
refreshText(showText + "/=" +result);
break;
default:
//上次结果已算出
if(result.length() > 0 && operator.equals("")){
clear();
}
if(operator.equals("")){
firstNum = firstNum + inputText;
}else {
secondNum = secondNum + inputText;
}
if (showText.equals("0")&& !inputText.equals(".")){
refreshText(inputText);
}else
{
refreshText(showText + inputText);
}
break;
}
}
//四则运算
private double caculateFour() {
switch (operator){
case "+":
return Double.parseDouble(firstNum) + Double.parseDouble(secondNum);
case "-":
return Double.parseDouble(firstNum) - Double.parseDouble(secondNum);
case "×":
return Double.parseDouble(firstNum) * Double.parseDouble(secondNum);
default:
return Double.parseDouble(firstNum) / Double.parseDouble(secondNum);
}
}
private void clear() {
refreshOperate("");
refreshText("");
}
//刷新运算结果
private void refreshOperate(String new_result){
result = new_result;
firstNum = result;
secondNum = "";
operator = "";
}
private void refreshText(String text){
showText = text;
tv_result.setText(showText);
}
}
3. Page layout
<?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:background="@color/pink"
android:padding="5dp"
android:orientation="horizontal"
tools:context=".activity.CalculatorActivity">
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="@string/lzh_calculator"
android:textColor="#CD7EB6EC"
android:textSize="20sp" />
<TextView
android:id="@+id/tv_result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/white"
android:gravity="right|bottom"
android:lines="3"
android:text="@string/zero"
android:textColor="@color/black"
android:textSize="25sp" />
<GridLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:columnCount="4"
android:rowCount="5">
<Button
android:id="@+id/btn_cancel"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/cancel"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_divide"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/divide"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_multiply"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/multiply"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_clear"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/clear"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_seven"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/seven"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_eight"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/eight"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_nine"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/nine"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_plus"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/plus"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_four"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/four"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_five"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/five"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_six"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/six"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_minus"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/minus"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_one"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/one"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_two"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/two"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_three"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/three"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_sqrt"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/sqrt"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_1_x"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/reciprocal"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_zero"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/zero"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_dot"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/dot"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
<Button
android:id="@+id/btn_equal"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_columnWeight="1"
android:gravity="center"
android:text="@string/equal"
android:textColor="@color/black"
android:textSize="30sp">
</Button>
</GridLayout>
</LinearLayout>
</ScrollView>
</LinearLayout>