android 开发 简单的小计算器
↑大致效果
项目构成：
随便写的，用的线性布局
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="top|center"
android:orientation="vertical"
android:padding="5dp">
<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"
android:showDividers="middle"> <LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"> <TextView
android:layout_marginBottom="20dp"
android:id="@+id/tv_result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="right|bottom"
android:lines="3"
android:maxLines="3"
android:scrollbars="vertical"
android:textColor="#000000"
android:textSize="38dp" />
</LinearLayout> <LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:showDividers="middle"> <LinearLayout
android:layout_width="match_parent"
android:layout_height="75dp"
android:orientation="horizontal"
android:showDividers="middle"> <Button
android:id="@+id/btn_cancel"
style="@style/btn_cal"
android:text="CE" /> <Button
android:id="@+id/btn_clear"
style="@style/btn_cal"
android:text="C" /> <Button
android:id="@+id/btn_sqrt"
style="@style/btn_cal"
android:text="√" /> <Button
android:id="@+id/btn_plus"
style="@style/btn_cal"
android:text="＋" />
</LinearLayout> <LinearLayout
android:layout_width="match_parent"
android:layout_height="75dp"
android:orientation="horizontal"
android:showDividers="middle"> <Button
android:id="@+id/btn_seven"
style="@style/btn_cal"
android:text="7" /> <Button
android:id="@+id/btn_eight"
style="@style/btn_cal"
android:text="8" /> <Button
android:id="@+id/btn_nine"
style="@style/btn_cal"
android:text="9" /> <Button
android:id="@+id/btn_minus"
style="@style/btn_cal"
android:text="－" /> </LinearLayout> <LinearLayout
android:layout_width="match_parent"
android:layout_height="75dp"
android:orientation="horizontal"
android:showDividers="middle"> <Button
android:id="@+id/btn_four"
style="@style/btn_cal"
android:text="4" /> <Button
android:id="@+id/btn_five"
style="@style/btn_cal"
android:text="5" /> <Button
android:id="@+id/btn_six"
style="@style/btn_cal"
android:text="6" /> <Button
android:id="@+id/btn_multiply"
style="@style/btn_cal"
android:text="×" />
</LinearLayout> <LinearLayout
android:layout_width="match_parent"
android:layout_height="75dp"
android:orientation="horizontal"
android:showDividers="middle"> <Button
android:id="@+id/btn_one"
style="@style/btn_cal"
android:text="1" /> <Button
android:id="@+id/btn_two"
style="@style/btn_cal"
android:text="2" /> <Button
android:id="@+id/btn_three"
style="@style/btn_cal"
android:text="3" /> <Button
android:id="@+id/btn_divide"
style="@style/btn_cal"
android:text="÷" />
</LinearLayout> <LinearLayout
android:layout_width="match_parent"
android:layout_height="75dp"
android:orientation="horizontal"
android:showDividers="middle"> <Button
android:id="@+id/btn_zero"
style="@style/btn_cal"
android:layout_weight="2"
android:text="0" /> <Button
android:id="@+id/btn_dot"
style="@style/btn_cal"
android:text="．" /> <Button
android:id="@+id/btn_equal"
style="@style/btn_cal"
android:text="＝" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
</ScrollView>
</LinearLayout>
</android.support.constraint.ConstraintLayout>
Main_activiity类：
package com.example.myapplication6; 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; public class MainActivity extends AppCompatActivity {
double sum = 0.0;
double temp = 0.0;
int op = -1;
double step = 1;
boolean positive = true;
boolean flag = true;
TextView tv = null;
Button sqrt = null;
Button C = null;
Button CE = null;
Button dot = null;
Button num1 = null;
Button num2 = null;
Button num3 = null;
Button num4 = null;
Button num5 = null;
Button num6 = null;
Button num7 = null;
Button num8 = null;
Button num9 = null;
Button num0 = null;
Button plus = null;
Button subtract = null;
Button multiply = null;
Button divide = null;
Button equal = null;
NumUtil numUtil = new NumUtil();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final TextView tv=(TextView) findViewById(R.id.tv_result);
num0 = (Button) findViewById(R.id.btn_zero);
num0.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(temp < 0.00000001 && temp > 0.0)
tv.setText("0");
else{
if(flag){
temp *= 10;
}else {
step /= 10;
}
tv.setText(numUtil._tv(temp));
}
}
});
num1 = (Button) findViewById(R.id.btn_one);
num1.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 1;
}else {
step /= 10;
temp += step * 1.0;
}
tv.setText(numUtil._tv(temp));
}
});
num2 = (Button) findViewById(R.id.btn_two);
num2.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 2;
}else {
step /= 10;
temp += step * 2;
}
tv.setText(numUtil._tv(temp));
}
});
num3 = (Button) findViewById(R.id.btn_three);
num3.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 3;
}else {
step /= 10;
temp += step * 3;
}
tv.setText(numUtil._tv(temp));
}
});
num4 = (Button) findViewById(R.id.btn_four);
num4.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 4;
}else {
step /= 10;
temp += step * 4;
}
tv.setText(numUtil._tv(temp));
}
});
num5 = (Button) findViewById(R.id.btn_five);
num5.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 5;
}else {
step /= 10;
temp += step * 5;
}
tv.setText(numUtil._tv(temp));
}
});
num6 = (Button) findViewById(R.id.btn_six);
num6.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 6;
}else {
step /= 10;
temp += step * 6;
}
tv.setText(numUtil._tv(temp));
}
});
num7 = (Button) findViewById(R.id.btn_seven);
num7.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 7;
}else {
step /= 10;
temp += step * 7;
}
tv.setText(numUtil._tv(temp));
}
});
num8 = (Button) findViewById(R.id.btn_eight);
num8.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 8;
}else {
step /= 10;
temp += step * 8;
}
tv.setText(numUtil._tv(temp));
}
});
num9 = (Button) findViewById(R.id.btn_nine);
num9.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
temp *= 10;
temp += 9;
}else {
step /= 10;
temp += step * 9;
}
tv.setText(numUtil._tv(temp));
}
});
dot = (Button) findViewById(R.id.btn_dot);
dot.setOnClickListener(new View.OnClickListener() { @Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
flag = false;
tv.setText(numUtil._tv(temp)+".");
}
}
});
equal = (Button) findViewById(R.id.btn_equal);
equal.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(op == -1){
sum = temp;
}else if(op == 1){
sum += temp;
}else if(op == 2){
sum -= temp;
}else if(op == 3){
sum *= temp;
}else if(op == 4){
sum /= temp;
}
tv.setText(numUtil._tv(sum));
positive = true;
flag = true;
sum = 0.0;
temp = 0.0;
step = 1.0;
op = -1;
}
});
plus = (Button) findViewById(R.id.btn_plus);
plus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
tv.setText("+");
if(op == -1){
sum = temp;
temp = 0.0;
}else{
if(op == 1){
sum += temp;
}else if(op == 2){
sum -= temp;
}else if(op == 3){
sum *= temp;
}else if(op == 4){
sum /= temp;
}
}
op = 1;
temp = 0.0;
positive = true;
flag = true;
}
});
subtract = (Button) findViewById(R.id.btn_minus);
subtract.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
tv.setText("-");
if(op == -1){
sum = temp;
temp = 0.0;
}else{
if(op == 1){
sum += temp;
}else if(op == 2){
sum -= temp;
}else if(op == 3){
sum *= temp;
}else if(op == 4){
sum /= temp;
}
}
op = 2;
temp = 0.0;
positive = true;
flag = true;
}
});
multiply = (Button) findViewById(R.id.btn_multiply);
multiply.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
tv.setText("×");
if(op == -1){
sum = temp;
temp = 0.0;
}else{
if(op == 1){
sum += temp;
}else if(op == 2){
sum -= temp;
}else if(op == 3){
sum *= temp;
}else if(op == 4){
sum /= temp;
}
}
op = 3;
temp = 0.0;
positive = true;
flag = true;
}
});
divide = (Button) findViewById(R.id.btn_divide);
divide.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
tv.setText("÷");
if(op == -1){
sum = temp;
temp = 0.0;
}else{
if(op == 1){
sum += temp;
}else if(op == 2){
sum -= temp;
}else if(op == 3){
sum *= temp;
}else if(op == 4){
sum /= temp;
}
}
op = 4;
temp = 0.0;
positive = true;
flag = true;
}
});
C = (Button) findViewById(R.id.btn_cancel);
C.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
tv.setText(" ");
positive = true;
flag = true;
temp = 0.0;
}
});
CE = (Button) findViewById(R.id.btn_clear);
CE.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
tv.setText(" ");
positive = true;
flag = true;
sum = 0.0;
temp = 0.0;
step = 1.0;
op = -1;
}
});
sqrt = (Button) findViewById(R.id.btn_sqrt);
sqrt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(op == -1){
sum = temp;
}else if(op == 1){
sum += temp;
}else if(op == 2){
sum -= temp;
}else if(op == 3){
sum *= temp;
}else if(op == 4){
sum /= temp;
}
sum = Math.sqrt(sum);
tv.setText(numUtil._tv(sum));
positive = true;
flag = true;
sum = 0.0;
temp = 0.0;
step = 1.0;
op = -1;
}
});
} }
NumUtil工具类：
package com.example.myapplication6;
public class NumUtil {
public double toDouble(String str){
return 0.0;
}
public String _tv(double x){
double t = x - (int) x;
if(t < 0)
t = -t;
if(t < 0.00000001)
return String.valueOf((int)x);
else{
String temp = String.format("%.7f", x);
for(int i = temp.length() -1; i >= 0; i--){
if(temp.substring(i,i+1).equals("0")){
continue;
}else{
if(i + 1 < temp.length()){
temp = temp.substring(0,i+1);
}
break;
}
}
return temp;
}
}
}
按钮的垃圾设定
<style name="btn_cal">
<item name="android:layout_marginLeft">3dp</item>
<item name="android:layout_width">wrap_content</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:background">#EEA9B8</item>
<item name="android:textSize">30px</item>
</style>
不太好弄的地方就是对于小数点后的处理了，剩下的随便写写就完事了
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