計算器的功能大家都是很熟悉的，這裏不用多說，直接貼代碼，覺得方便的話大夥就可以粘去用0.0
控件初始化和綁定監聽器使用了一個工具[link]https://www.buzzingandroid.com/tools/android-layout-finder/
效果演示
代碼
佈局是很隨意的，大家可以自己寫0.0
<?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"
tools:context=".MainActivity"
android:orientation="vertical"
>
<!--文本標籤-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_columnSpan="4"
android:layout_marginLeft="4px"
android:gravity="left"
android:text="0"
android:textSize="50dip"
/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<Button android:id="@+id/qingchu" android:text="C" android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="26sp"/>
<Button android:id="@+id/del" android:text="DEL" android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="26sp"/>
</LinearLayout>
<!--網格佈局-->
<GridLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:rowCount="4"
android:columnCount="4"
>
<Button android:id="@+id/button7" android:text="7" android:textSize="28sp" />
<Button android:id="@+id/button8" android:text="8" android:textSize="28sp" />
<Button android:id="@+id/button9" android:text="9" android:textSize="28sp" />
<Button android:id="@+id/reduce" android:text="-" android:textSize="28sp" />
<Button android:id="@+id/button4" android:text="4" android:textSize="28sp" />
<Button android:id="@+id/button5" android:text="5" android:textSize="28sp" />
<Button android:id="@+id/button6" android:text="6" android:textSize="28sp" />
<Button android:id="@+id/add" android:text="+" android:textSize="28sp" />
<Button android:id="@+id/button1" android:text="1" android:textSize="28sp" />
<Button android:id="@+id/button2" android:text="2" android:textSize="28sp" />
<Button android:id="@+id/button3" android:text="3" android:textSize="28sp" />
<Button android:id="@+id/cheng" android:text="×" android:textSize="28sp" />
<Button android:id="@+id/dian" android:text="." android:textSize="28sp" />
<Button android:id="@+id/button0" android:text="0" android:textSize="28sp" />
<Button android:id="@+id/equal" android:text="=" android:textSize="28sp" />
<Button android:id="@+id/chu" android:text="÷" android:textSize="28sp" />
</GridLayout>
</LinearLayout>
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private static final String TAG = MainActivity.class.getSimpleName();
private Button qingchu;
private Button del;
private Button button7;
private Button button8;
private Button button9;
private Button reduce;
private Button button4;
private Button button5;
private Button button6;
private Button add;
private Button button3;
private Button button2;
private Button button1;
private Button cheng;
private Button dian;
private Button button0;
private Button equal;
private Button chu;
private TextView textView;
private List<Character> strs;//用來存當前輸入要計算的數字
private double last=-1000;//用來記錄每次計算後上一次的數值
private double current;//用來記錄當前輸入要計算的數字，從strs中轉化而來
private double sum=-1000;//用來記錄當前計算後的值，之後賦值給last
private char lastChar='1';//用來記錄上一次輸入的計算符號
private boolean isFirst =true;//第一次輸入或者每次清空後 sum的值在第一次要有current賦值給他 不然完成last = sum會產生錯誤結果
private boolean isYunsuan =false;//判斷是否要進行計算
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViews();
setListener();
}
/**
* Find the Views in the layout<br />
* <br />
* Auto-created on 2019-03-16 20:49:35 by Android Layout Finder
* (http://www.buzzingandroid.com/tools/android-layout-finder)
*/
private void findViews() {
qingchu = (Button)findViewById( R.id.qingchu );
del = (Button)findViewById( R.id.del );
button7 = (Button)findViewById( R.id.button7 );
button8 = (Button)findViewById( R.id.button8 );
button9 = (Button)findViewById( R.id.button9 );
reduce = (Button)findViewById( R.id.reduce );
button4 = (Button)findViewById( R.id.button4 );
button5 = (Button)findViewById( R.id.button5 );
button6 = (Button)findViewById( R.id.button6 );
add = (Button)findViewById( R.id.add );
button3 = (Button)findViewById( R.id.button3 );
button2 = (Button)findViewById( R.id.button2 );
button1 = (Button)findViewById( R.id.button1 );
cheng = (Button)findViewById( R.id.cheng );
dian = (Button)findViewById( R.id.dian );
button0 = (Button)findViewById( R.id.button0 );
equal = (Button)findViewById( R.id.equal );
chu = (Button)findViewById( R.id.chu );
textView = (TextView)findViewById(R.id.tv);
strs = new ArrayList<>();
}
private void setListener() {
qingchu.setOnClickListener( this );
del.setOnClickListener( this );
button7.setOnClickListener( this );
button8.setOnClickListener( this );
button9.setOnClickListener( this );
reduce.setOnClickListener( this );
button4.setOnClickListener( this );
button5.setOnClickListener( this );
button6.setOnClickListener( this );
add.setOnClickListener( this );
button3.setOnClickListener( this );
button2.setOnClickListener( this );
button1.setOnClickListener( this );
cheng.setOnClickListener( this );
dian.setOnClickListener( this );
button0.setOnClickListener( this );
equal.setOnClickListener( this );
chu.setOnClickListener( this );
}
/**
* Handle button click events<br />
* <br />
* Auto-created on 2019-03-16 20:49:35 by Android Layout Finder
* (http://www.buzzingandroid.com/tools/android-layout-finder)
*/
@Override
public void onClick(View v) {
if ( v == qingchu ) {//清除操作要把值初始化
// Handle clicks for qingchu
textView.setText("0");
strs = new ArrayList<>();
isFirst = true;
current = 0;
lastChar='1';
} else if ( v == del ) {
// Handle clicks for del
if (strs.size()>0&&strs!=null) {
strs.remove(strs.size() - 1);
update('0');
if (strs.size()==0){//剩下一個數減的話就置爲0
textView.setText("0");
}
}
} else if ( v == button7 ) {
// Handle clicks for button7
strs.add('7');
update('0');
} else if ( v == button8 ) {
// Handle clicks for button8
strs.add('8');
update('0');
} else if ( v == button9 ) {
// Handle clicks for button9
strs.add('9');
update('0');
} else if ( v == reduce ) {
// Handle clicks for reduce
update('-');
} else if ( v == button4 ) {
// Handle clicks for button4
strs.add('4');
update('0');
} else if ( v == button5 ) {
// Handle clicks for button5
strs.add('5');
update('0');
} else if ( v == button6 ) {
// Handle clicks for button6
strs.add('6');
update('0');
} else if ( v == add ) {
// Handle clicks for add
update('+');
} else if ( v == button3 ) {
// Handle clicks for button3
strs.add('3');
update('0');
} else if ( v == button2 ) {
// Handle clicks for button2
strs.add('2');
update('0');
} else if ( v == button1 ) {
// Handle clicks for button1
strs.add('1');
update('0');
} else if ( v == cheng ) {
// Handle clicks for cheng
update('×');
} else if ( v == dian ) {
// Handle clicks for dian
//這裏的操作是爲了避免輸入多個'.' 小數點只有一位
boolean isNone = true;
for (char c :strs){
if (c == '.'){
isNone = false;
}
}
if (isNone) {
strs.add('.');
update('0');
}
} else if ( v == button0 ) {
// Handle clicks for button0
strs.add('0');
update('0');
} else if ( v == equal ) {
// Handle clicks for equal
update('=');
} else if ( v == chu ) {
// Handle clicks for chu
update('÷');
}
}
private void update(char x) {
//遍歷集合 轉化爲String類型方便顯示
String str = "";
for(char c : strs){
str +=c;
}
//str！=''是因爲Double.valueof不是轉化“”這個字符串
if (x=='0'&&str!="") {
textView.setText(str);
current = Double.valueOf(str);
}
//第一次輸入的賦值，不這樣做下面的last = sum 會產生錯誤結果
if (isFirst){sum = current;}
//進行符號判斷並在textview顯示符號
if (x == '-'){
textView.setText("-");
strs = new ArrayList<>();isFirst = false;
}else if (x == '+'){
textView.setText("+");
strs = new ArrayList<>();isFirst = false;
}else if (x == '×'){
textView.setText("×");
strs = new ArrayList<>();isFirst = false;
}else if (x == '÷'){
textView.setText("÷");
strs = new ArrayList<>();isFirst = false;
}
/**
* lastChar！=‘1’是爲了保證在獲得符號才進入計算
* isYuansuan 比如要輸入11x11 這個運算 因爲我們這個函數是每次輸入一個char（數字）就會更新一次，我們希望
* 不會再輸入到11x1 的時候 就進入這個運算判斷，而是等到我們輸入到11x11 後面再接一個符號才運算，
* isYunsuan也是在這個時候爲true的，這樣才能保證運算正確
*/
if (lastChar!='1'&&isYunsuan&&x!='0'){
//計算值
if (lastChar=='-'){
sum = last - current;
}else if (lastChar=='+'){
sum = last + current;
}else if (lastChar=='×'){
sum = (last * current);
}else if (lastChar=='÷'){
sum = (last / current);
}
isYunsuan = false;//運算完成後置位false
}
last = sum;//保存當前計算結果到last 用於下一次的計算
if (x!='0') {
lastChar = x;
isYunsuan = true;
}
//當按‘=’的時候，進行輸出結果
if (x=='='){
textView.setText(sum+"");
lastChar = '1';
strs = new ArrayList<>();
}
}
}