exam01--2

终于让我完整地做了一道题，哭泣器
效果图

esvaluesstring.xml

<resources>
    <string name="app_name">exam2</string>
    <string-array name="data">
        <item>+</item>
        <item>-</item>
        <item>*</item>
        <item>÷</item>
    </string-array>
</resources>

axtivity.xml

<?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">

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <EditText
            android:id="@+id/id_edittext1"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="2" />

        <TextView
            android:id="@+id/id_textview_symbol"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"/>

        <Spinner
            android:id="@+id/id_spinner"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">

        </Spinner>

        <EditText
            android:id="@+id/id_edittext2"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="2" />

        <Button
            android:id="@+id/id_btn"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="=" />

        <TextView
            android:id="@+id/id_textview_result"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="3"
            android:gravity="center"/>
    </LinearLayout>

    <ListView
        android:id="@+id/id_listview"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

MainActivity.java

package com.example.exam2;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;

import org.w3c.dom.Text;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private EditText editText1,editText2;
    private TextView textView_symbol,textView_result;
    private Spinner spinner;
    private Button btn_equal;
    private ListView listView;
    private List<String> list = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();

        //获取xml文件中字符串数组
        final String datas[] = getResources().getStringArray(R.array.data);
        //初始化适配器
        ArrayAdapter adapter1 = new ArrayAdapter(this,android.R.layout.simple_list_item_1,datas);
        final ArrayAdapter adapter2 = new ArrayAdapter(this,android.R.layout.simple_list_item_1,list);
        //绑定适配器
        spinner.setAdapter(adapter1);
        listView.setAdapter(adapter2);

        //spinner的点击事件
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                textView_symbol.setText(datas[position]);
            }

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

            }
        });
        //Button的点击事件
        btn_equal.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                textView_result.setText(cal(textView_symbol.getText()+"",editText1.getText()+"",editText2.getText()+""));
                String str = editText1.getText()+""+textView_symbol.getText()+editText2.getText()+"="+textView_result.getText();
                list.add(str);
                adapter2.notifyDataSetChanged();
            }
        });

    }

    public String cal(String symbol,String first,String second){
        double s=0;
        Double d1 = Double.parseDouble(first);
        Double d2 = Double.parseDouble(second);
        switch (symbol){
            case "+":
                s=d1+d2;
                break;
            case "-":
                s=d1-d2;
                break;
            case "*":
                s=d1*d2;
                break;
            case "÷":
                s=d1/d2;
                break;
        }
        return s+"";
    }
    public void initView(){
        editText1 = (EditText)findViewById(R.id.id_edittext1);
        editText2 = (EditText)findViewById(R.id.id_edittext2);
        textView_symbol = (TextView)findViewById(R.id.id_textview_symbol);
        textView_result = (TextView)findViewById(R.id.id_textview_result);
        spinner = (Spinner)findViewById(R.id.id_spinner);
        btn_equal = (Button)findViewById(R.id.id_btn);
        listView = (ListView)findViewById(R.id.id_listview);
    }
}