Android如何實現簡單計算器

這篇文章主要介紹了Android如何實現簡單計算器，具有一定借鑒價值，感興趣的朋友可以參考下，希望大家閱讀完這篇文章之后大有收獲，下面讓小編帶著大家一起了解一下。

具體內容如下

功能

1、加減乘除四則運算
2、歸0
3、回退
4、即時運算

配置

在build.gradle(app) 中加入下面的代碼

buildFeatures {
        viewBinding = true
    }

加入位置如下所示

compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
buildFeatures {
    viewBinding = true
}

布局

<?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:orientation="vertical"
    >
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="4"
        android:layout_margin="5dp"
        android:text="計算器\nby csdn weixin_44423317 "
        android:textSize="20sp"
        android:gravity="right|center"
        android:padding="6dp"
        />
    <View
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:layout_marginLeft="1dp"
        android:layout_marginRight="1dp"
        android:background="#ADADAD"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="8"
        android:orientation="vertical"
        android:gravity="center_horizontal"
        >
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:orientation="horizontal">
            <Button
                android:id="@+id/ac"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:text="AC"
                android:background="@color/white"/>
            <Button
                android:layout_weight="1"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:background="#00FFFFFF"/>
            <Button
                android:layout_weight="1"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:background="#00FFFFFF"/>
            <ImageButton
                android:id="@+id/dec"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:layout_gravity="right"
                android:background="@color/white"
                android:src="@drawable/ic_baseline_backspace_24"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:orientation="horizontal">
            <Button
                android:id="@+id/qi"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:text="7"
                android:background="@color/white"/>
            <Button
                android:id="@+id/ba"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:text="8"
                android:background="@color/white"/>
            <Button
                android:id="@+id/jiu"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:text="9"
                android:textSize="20sp"
                android:background="@color/white"/>
            <Button
                android:id="@+id/mul"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:text="x"
                android:background="@color/white"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:orientation="horizontal">
            <Button
                android:id="@+id/si"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:textSize="20sp"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:text="4"
                android:background="@color/white"/>
            <Button
                android:id="@+id/wu"
                android:textSize="20sp"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:text="5"
                android:background="@color/white"/>
            <Button
                android:id="@+id/liu"
                android:textSize="20sp"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:text="6"
                android:background="@color/white"/>
            <Button
                android:id="@+id/div"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:textSize="20sp"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:text="/"
                android:background="@color/white"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:orientation="horizontal">
            <Button
                android:id="@+id/yi"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:textSize="20sp"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:text="1"
                android:background="@color/white"/>
            <Button
                android:id="@+id/er"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textSize="20sp"
                android:textColor="@color/black"
                android:text="2"
                android:background="@color/white"/>
            <Button
                android:id="@+id/san"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:textSize="20sp"
                android:text="3"
                android:background="@color/white"/>
            <Button
                android:id="@+id/sub"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:textSize="20sp"
                android:text="-"
                android:background="@color/white"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:orientation="horizontal">
            <Button
                android:id="@+id/zero"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:textSize="20sp"
                android:text="0"
                android:background="@color/white"/>
            <Button
                android:id="@+id/point"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:textSize="20sp"
                android:text="."
                android:background="@color/white"/>
            <Button
                android:id="@+id/equal"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:textSize="20sp"
                android:text="="
                android:background="@color/white"/>
            <Button
                android:id="@+id/add"
                android:layout_width="0dp"
                android:layout_weight="1"
                android:layout_height="match_parent"
                android:textColor="@color/black"
                android:textSize="20sp"
                android:text="+"
                android:background="@color/white"/>
        </LinearLayout>
    </LinearLayout>
</LinearLayout>

代碼

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private String tv="0";
    private ActivityMainBinding inflate;
    private String count="";
    private boolean isMax=false;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        inflate = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(inflate.getRoot());
        inflate.zero.setOnClickListener(this);
        inflate.yi.setOnClickListener(this);
        inflate.er.setOnClickListener(this);
        inflate.san.setOnClickListener(this);
        inflate.si.setOnClickListener(this);
        inflate.wu.setOnClickListener(this);
        inflate.liu.setOnClickListener(this);
        inflate.qi.setOnClickListener(this);
        inflate.ba.setOnClickListener(this);
        inflate.jiu.setOnClickListener(this);
        inflate.add.setOnClickListener(this);
        inflate.sub.setOnClickListener(this);
        inflate.mul.setOnClickListener(this);
        inflate.div.setOnClickListener(this);
        inflate.point.setOnClickListener(this);
        inflate.equal.setOnClickListener(this);
        inflate.dec.setOnClickListener(this);
        inflate.ac.setOnClickListener(this);
    }
    private void jisuanqi(){
        List<String> strs=new ArrayList<>();
        StringBuilder f= new StringBuilder();
        for(int i=0;i<tv.length();i++) {
            if(String.valueOf(tv.charAt(i)).equals("-")) {
                if(!f.toString().equals("")){
                    strs.add(f.toString());
                    strs.add("-");
                    f = new StringBuilder();
                }else{
                    f.append("-");
                }
                continue;
            }
            if(String.valueOf(tv.charAt(i)).matches("(\\d+)|(\\.)")) {
                f.append(String.valueOf(tv.charAt(i)));
            }else {
                strs.add(f.toString());
                strs.add(String.valueOf(tv.charAt(i)));
                f = new StringBuilder();
            }
        }
        if(!f.toString().equals("")) {
            strs.add(f.toString());
        }
        if(!strs.get(strs.size()-1).matches("(\\-|)?\\d+(\\.\\d*)?$")){
            strs.remove(strs.size()-1);
        }
        double ans=number(strs,0);
        if(ans==0||ans%(int)ans==0){
            count=(int)ans+"";
        }else {
            BigDecimal bigdecimal=new BigDecimal(ans);
            String a=bigdecimal.setScale(12,5).toString();
            if(ans-(int)ans!=0) {
                while (String.valueOf(a.charAt(a.length() - 1)).equals("0")){
                    a=a.substring(0,a.length()-1);
                }
            }
            count=a;
        }
        if(isMax){
            isMax=false;
            count="∞";
        }
        showText();
    }
    private void showText(){
        inflate.tv.setText(tv);
        SpannableString spanText  =  new SpannableString(count);
        spanText.setSpan(new AbsoluteSizeSpan(30, true), 0, spanText.length(),
                Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        inflate.tv.append("\n");
        inflate.tv.append(spanText);
    }
    private double number(List<String> n,int v) {
        double con = 0;
        int j=0;
        con=Double.valueOf(n.get(0));
        if(v==0) {
            for(int i=0;i<n.size();i++) {
                if(n.get(i).matches("(\\-|)?\\d+(\\.\\d+)?$")) {//55+5*5/5-5=
                    con=Double.valueOf(n.get(i));
                    if(n.size()>i+1) {
                        j=i+1;
                    }
                }
                if(n.get(j).equals("x")){
                    n.set(i, String.valueOf(con*Double.valueOf(n.get(i+2))));
                    n.remove(i+1);
                    n.remove(i+1);
                    return number(n,0);
                }else if(n.get(j).equals("/")){
                    if(Double.valueOf(n.get(i+2))==0){
                        isMax=true;
                        return 10;
                    }
                    n.set(i, String.valueOf(con/Double.valueOf(n.get(i+2))));
                    n.remove(i+1);
                    n.remove(i+1);
                    return number(n,0);
                }
            }
        }
        for(int i=0;i<n.size();i++) {
            if(n.get(i).matches("(\\-|)?\\d+(\\.\\d+)?$")) {//55+5*5/5-5=
                con=Double.valueOf(n.get(i));
                if(n.size()>i+1) {
                    j=i+1;
                }
            }
            if(n.get(j).equals("+")){
                n.set(i, String.valueOf(con+Double.valueOf(n.get(i+2))));
                n.remove(i+1);
                n.remove(i+1);
                return number(n,1);

            }else if(n.get(j).equals("-")){
                n.set(i, String.valueOf(con-Double.valueOf(n.get(i+2))));
                n.remove(i+1);
                n.remove(i+1);
                return number(n,1);
            }

        }
        return con;
    }

    @SuppressLint("NonConstantResourceId")
    @Override
    public void onClick(View v) {

        switch (v.getId()){
            case R.id.point:
                if(String.valueOf(tv.charAt(tv.length()-1)).matches("\\d+")){
                    tv+=".";
                    inflate.tv.setText(tv);
                }
                break;
            case R.id.zero:
            case R.id.yi:
            case R.id.er:
            case R.id.san:
            case R.id.si:
            case R.id.wu:
            case R.id.liu:
            case R.id.qi:
            case R.id.ba:
            case R.id.jiu:
                if(tv.equals("0")){
                    tv="";
                }
                Button bt_digit=findViewById(v.getId());
                tv+=bt_digit.getText();
                inflate.tv.setText(tv);
                count=tv;
                jisuanqi();
                break;
            case R.id.sub:
                if(String.valueOf(tv.charAt(0)).equals("0")){
                    tv="-";
                }else {
                    if(String.valueOf(tv.charAt(tv.length()-1)).equals(".")){
                        tv += "0";
                    }
                    tv+="-";
                }
                showText();
                break;
            case R.id.add:
            case R.id.mul:
            case R.id.div:
                Button bt_operator=findViewById(v.getId());
                String laststr=String.valueOf(tv.charAt(tv.length()-1));
                if(!laststr.matches("(\\d+)") ) {
                    tv = tv.substring(0, tv.length() - 1) + bt_operator.getText();
                }else {
                    if(laststr.equals(".")) {
                        tv += "0";
                    }
                    tv+=bt_operator.getText();
                }

                showText();
                break;
            case R.id.ac:
                tv="0";
                inflate.tv.setText(tv);
                break;
            case R.id.dec:
                if(tv.length()>1) {
                    tv = tv.substring(0, tv.length() - 1);
                }else {
                    tv="0";
                }
                jisuanqi();
                break;
            case R.id.equal:
                if(!String.valueOf(tv.charAt(tv.length()-1)).matches("(\\d+)")){
                    tv = tv.substring(0, tv.length() - 1);
                }
                count=tv;
                jisuanqi();
                tv=count;
                inflate.tv.setText(tv);
                break;
        }
    }
 }

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