第一个作业（计算器）

activity-main主界面：

核心代码：

<?xml version="1.0" encoding="utf-8"?>
<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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.example.administrator.myapplication.MainActivity">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:weightSum="1">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/factorOne" />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:text="乘以"
            android:id="@+id/symbol"
            android:layout_weight="0.10" />

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/factorTwo"
            android:layout_gravity="center_horizontal" />

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="计算"
            android:id="@+id/calculate"
            android:layout_gravity="center_horizontal"
            android:layout_weight="0.04" />

    </LinearLayout>
</RelativeLayout>

resultactivity界面：

核心代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="526dp"
        android:weightSum="1">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="3dp"
            android:id="@+id/resultView"
            android:layout_gravity="center_horizontal"
            android:layout_weight="0.10"
            android:text="result" />
    </LinearLayout>
</LinearLayout>

MainActivity.java
核心代码：
package com.example.administrator.myapplication;

import android.content.DialogInterface;
import android.content.Intent;
import android.support.v4.media.MediaMetadataCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private EditText factorOne;
    private EditText factorTwo;
    private TextView symbol;
    private Button calculate;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        factorOne = (EditText)findViewById(R.id.factorOne);
        factorTwo = (EditText)findViewById(R.id.factorTwo);
        symbol = (TextView)findViewById(R.id.symbol);
        calculate = (Button)findViewById(R.id.calculate);

        symbol.setText(R.string.symbol);
        calculate.setText(R.string.calculate);
        calculate.setOnClickListener(new CalculateListener());
    }

    class CalculateListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            String factorOneStr = factorOne.getText().toString();
            String factorTwoStr = factorTwo.getText().toString();

            Intent intent = new Intent();
            intent.putExtra("one",factorOneStr);
            intent.putExtra("two",factorTwoStr);
            intent.setClass(MainActivity.this,ResultActivity.class);
            MainActivity.this.startActivity(intent);
        }

    }


}
第一次做的小程序，感觉还是挺不错的，很有成就感，虽然遇到很多问题。