android利用spinner选择加减乘除进行运算！！！！

#android利用spinner选择加减乘除进行运算！！！！
##效果图

##代码部分
.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<EditText
android:id="@+id/edt_test1"
android:layout_width="60dip"
android:layout_height="40dip"
android:ems="10"
android:inputType="number"
android:textColor="#88e355"
android:textSize="20sp" />

<Spinner
android:id="@+id/spinner"
android:layout_width="60dip"
android:layout_height="40dip"/>

<EditText
android:id="@+id/edt_test2"
android:layout_width="60dip"
android:layout_height="40dip"
android:ems="10"
android:inputType="number"
android:textColor="#88e355"
android:textSize="20sp" />

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="=" />

<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="" />

</LinearLayout>

.java

package com.example.test1_2;

import android.app.Activity;
import android.app.AlertDialog;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;

public class MainActivity extends Activity {

private Spinner spinner;
private EditText editNum1;
private EditText editNum2;
private TextView result;
private Button button;
private String[] huansaun = {"+","-","×","÷"};
String flag;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

spinner = (Spinner) findViewById(R.id.spinner);
editNum1 = (EditText) findViewById(R.id.edt_test1);
editNum2 = (EditText) findViewById(R.id.edt_test2);
button = (Button) findViewById(R.id.button1);
result = (TextView) findViewById(R.id.tv);

ArrayAdapter<String> huansuan_adapter = new ArrayAdapter<String>(
this,android.R.layout.simple_spinner_dropdown_item,huansaun
);
spinner.setAdapter(huansuan_adapter);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
flag = spinner.getSelectedItem().toString();
Log.e("Dawangba", String.valueOf(position));
}

@Override
public void onNothingSelected(AdapterView<?> parent) {

}
});

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (flag.equals("+")){
AddListener addListener = new AddListener();
addListener.onClick(v);
}

if (flag.equals("-")){
SubListener subListener = new SubListener();
subListener.onClick(v);
}
if (flag.equals("×")){
MulListener mulListener = new MulListener();
mulListener.onClick(v);
}
if (flag.equals("÷")){
DivListener divListener = new DivListener();
divListener.onClick(v);
}
}
});
}

private void showDialog(){
AlertDialog.Builder dialog = new AlertDialog.Builder(this);
dialog.setTitle("错误");
dialog.setMessage("输入数字无效!");
dialog.setPositiveButton("确定",null);
dialog.show();
}

//加法操作
private class AddListener implements View.OnClickListener {

public void onClick(View v) {

if (TextUtils.isEmpty(editNum1.getText().toString()) || TextUtils.isEmpty(editNum2.getText().toString())){
showDialog();
} else {
float number1 = Float.parseFloat((editNum1.getText().toString()));
float number2 = Float.parseFloat((editNum2.getText().toString()));
result.setText(number1 + number2 + "");
}
}
}

//减法操作
private class SubListener implements View.OnClickListener {
public void onClick(View v) {
if (TextUtils.isEmpty(editNum1.getText().toString()) || TextUtils.isEmpty(editNum2.getText().toString())){
showDialog();
} else {
float number1 = Float.parseFloat((editNum1.getText().toString()));
float number2 = Float.parseFloat((editNum2.getText().toString()));
result.setText(number1 - number2 + "");
}
}
}
//乘法操作
private class MulListener implements View.OnClickListener {
public void onClick(View v) {
if (TextUtils.isEmpty(editNum1.getText().toString()) || TextUtils.isEmpty(editNum2.getText().toString())){
showDialog();
} else {
float number1 = Float.parseFloat((editNum1.getText().toString()));
float number2 = Float.parseFloat((editNum2.getText().toString()));
result.setText(number1 * number2 + "");
}
}
}
//除法操作
private class DivListener implements View.OnClickListener {
public void onClick(View v) {
if (TextUtils.isEmpty(editNum1.getText().toString()) || TextUtils.isEmpty(editNum2.getText().toString())){
showDialog();
} else {
float number1 = Float.parseFloat((editNum1.getText().toString()));
float number2 = Float.parseFloat((editNum2.getText().toString()));
if (number2 == 0){
showDialog();
} else {
result.setText(number1 / number2 + "");
}
}
}
}
}

部分参照网络，些许bug，可以简单实现！！！