android项目编写计算器

效果：

 

步骤

  1、布局方式：网格布局（GridLayout）

6行4列，以、二两行是一行一列，其余四行是一行四列。

得到xml文件

main.xml

<RelativeLayout 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"
android:background="@drawable/image"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<GridLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:rowCount="6"
android:columnCount="4"
>
<EditText
android:id="@+id/tvResult"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_row="0"
android:layout_column="0"
android:layout_columnSpan="4"

android:textSize="25dp"
android:gravity="right"/>
<Button
android:id="@+id/btclean"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_row="1"
android:layout_column="0"
android:layout_columnSpan="4"
android:text="清除"
/>
<Button
android:id="@+id/bt7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="2"
android:layout_column="0"
android:text="7"
/>
<Button
android:id="@+id/bt8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="2"
android:layout_column="1"
android:text="8"
/>
<Button
android:id="@+id/bt9"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="2"
android:layout_column="2"
android:text="9"
/>
<Button
android:id="@+id/btDive"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="2"
android:layout_column="3"
android:text="%"
android:layout_gravity="fill_horizontal"
/>
<Button
android:id="@+id/bt4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="3"
android:layout_column="0"
android:text="4"
/>
<Button
android:id="@+id/bt5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="3"
android:layout_column="1"
android:text="5"
/>
<Button
android:id="@+id/bt6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="3"
android:layout_column="2"
android:text="6"
/>
<Button
android:id="@+id/btMulti"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="3"
android:layout_column="3"
android:text="*"
android:layout_gravity="fill_horizontal"
/>

<Button
android:id="@+id/bt1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="4"
android:layout_column="0"
android:text="1"
/>
<Button
android:id="@+id/bt2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="4"
android:layout_column="1"
android:text="2"
/>
<Button
android:id="@+id/bt3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="4"
android:layout_column="2"
android:text="3"
/>
<Button
android:id="@+id/btMinu"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="4"
android:layout_column="3"
android:text="-"
android:layout_gravity="fill_horizontal"
/>
<Button
android:id="@+id/bt_"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="5"
android:layout_column="0"
android:text="."
/>
<Button
android:id="@+id/bt0"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="5"
android:layout_column="1"
android:text="0"
/>
<Button
android:id="@+id/btEqual"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="5"
android:layout_column="2"
android:text="="
/>
<Button
android:id="@+id/btAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_row="5"
android:layout_column="3"
android:text="+"
android:layout_gravity="fill_horizontal"
/>

</GridLayout>


</RelativeLayout>

 demin.xml

<resources>

    <!-- Default screen margins, per the Android Design guidelines. -->
    <dimen name="activity_horizontal_margin">16dp</dimen>
    <dimen name="activity_vertical_margin">16dp</dimen>

</resources>

2、给button按钮注册监听器，三种类别：a，数字和小数点；b，加减乘除；c，等于号

Activity.java

package android.test;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


public class Laborary2Activity extends Activity {
/** Called when the activity is first created. */
EditText displayText=null;
double num1=0,num2=0,result=0;
int calType=0;
boolean flag=false;
Button bt0,bt1,bt2,bt3,bt4,bt5,bt6,bt7,bt8,bt9,bt_;
Button btEqual,btAdd,btMinu,btMulti,btDive,btclean;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
}
private void init() {
// TODO Auto-generated method stub
bt0=(Button)findViewById(R.id.bt0);
bt1=(Button)findViewById(R.id.bt1);
bt2=(Button)findViewById(R.id.bt2);
bt3=(Button)findViewById(R.id.bt3);
bt4=(Button)findViewById(R.id.bt4);
bt5=(Button)findViewById(R.id.bt5);
bt6=(Button)findViewById(R.id.bt6);
bt7=(Button)findViewById(R.id.bt7);
bt8=(Button)findViewById(R.id.bt8);
bt9=(Button)findViewById(R.id.bt9);
bt_=(Button)findViewById(R.id.bt_);
btEqual=(Button)findViewById(R.id.btEqual);
btAdd=(Button)findViewById(R.id.btAdd);
btMinu=(Button)findViewById(R.id.btMinu);
btMulti=(Button)findViewById(R.id.btMulti);
btDive=(Button)findViewById(R.id.btDive);
displayText=(EditText)findViewById(R.id.tvResult);
btclean=(Button)findViewById(R.id.btclean);
btclean.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
displayText.setText(null);
}


});
btAdd.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
CharSequence temp=displayText.getText();
if(temp.equals(null))
return;
String myString=temp.toString();
if(myString.equals("")||myString==null){
Toast.makeText(Laborary2Activity.this, "请输入被加数", Toast.LENGTH_LONG).show();
}
else{
num1=Double.parseDouble(myString);
calType=1;
displayText.setText(null);
}
}});
btMinu.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
CharSequence temp=displayText.getText();
if(temp.equals(null))
return;

String myString=temp.toString();
if(myString.equals("")||myString==null){
Toast.makeText(Laborary2Activity.this, "请输入被减数", Toast.LENGTH_LONG).show();
}else {num1=Double.parseDouble(myString);
calType=2;
displayText.setText(null);
}
}});
btMulti.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
CharSequence temp=displayText.getText();
if(temp.equals(null))
return;

String myString=temp.toString();
if(myString.equals("")||myString==null){
Toast.makeText(Laborary2Activity.this, "请输入乘数", Toast.LENGTH_LONG).show();
}
else
{
num1=Double.parseDouble(myString);
calType=3;
displayText.setText(null);
}
}});
btDive.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
CharSequence temp=displayText.getText();
if(temp.equals(null))
return;

String myString=temp.toString();
if(myString.equals("")||myString==null){
Toast.makeText(Laborary2Activity.this, "请输入被除数", Toast.LENGTH_LONG).show();
}
else
{num1=Double.parseDouble(myString);
calType=4;
displayText.setText(null);
}
}});
btEqual.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
CharSequence temp=displayText.getText();
if(temp.equals(null))return;
String myString=temp.toString();
if(myString.equals("")||myString==null){
Toast.makeText(Laborary2Activity.this, "你要计算什么？", Toast.LENGTH_LONG).show();
}
else{
num2=Double.parseDouble(myString);
switch(calType){
case 1:
{
result=num1+num2;
break;
}
case 2:
{
result=num1-num2;
break;
}
case 3:
{
result=num1*num2;
break;
}
case 4:
{
result=num1/num2;
break;
}
default:
{
result=0;
break;

}

}
String tempResult=String.valueOf(result);
displayText.setText(tempResult);
flag=true;
}
}});
bt_.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+".";
displayText.setText(myString);
}
});
bt9.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}

CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"9";
displayText.setText(myString);

}
});
bt8.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"8";
displayText.setText(myString);
}
});
bt7.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"7";
displayText.setText(myString);
}
});
bt6.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"6";
displayText.setText(myString);
}
});
bt5.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"5";
displayText.setText(myString);
}
});
bt4.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"4";
displayText.setText(myString);
}
});
bt3.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"3";
displayText.setText(myString);
}
});
bt2.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"2";
displayText.setText(myString);
}
});
bt1.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"1";
displayText.setText(myString);
}
});
bt0.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(flag){
displayText.setText(null);
flag=false;
}
CharSequence temp=displayText.getText();
String myString=temp.toString();
myString=myString+"0";
displayText.setText(myString);

}
});

}
}