第一个入门小程序加法器

MainActivity:
 1 package com.example.plus;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    private Button Count;
    private EditText Plus1;
    private EditText Plus2;

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

        Plus1 = (EditText) findViewById(R.id.plusone);
        Plus2 = (EditText) findViewById(R.id.plustwo);

        Count = (Button) findViewById(R.id.count);
        Count.setText("Count");

        TextView SymbolPlus = (TextView) findViewById(R.id.symbol);
        SymbolPlus.setText(R.string.symbol);

        Count.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                String Plus1str = Plus1.getText().toString();
                String Plus2str = Plus2.getText().toString();

                // 把控件的值放到Intent的Extra里面
                Intent ToResult = new Intent();
                ToResult.putExtra("one", Plus1str);
                ToResult.putExtra("two", Plus2str);

                ToResult.setClass(MainActivity.this, Result.class);
                MainActivity.this.startActivity(ToResult);

            }
        });
    }
}

Resule:

package com.example.plus;

import android.os.Bundle;
import android.widget.TextView;
import android.app.Activity;
import android.content.Intent;

public class Result extends Activity {
    private TextView answer;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.result);

        answer = (TextView) findViewById(R.id.Answer);

        Intent intent = getIntent();

        String Plus1 = intent.getStringExtra("one");
        String Plus2 = intent.getStringExtra("two");

        int num1 = Integer.parseInt(Plus1);
        int num2 = Integer.parseInt(Plus2);

        int result = num1 + num2;

        answer.setText(result + "");
    }
}

Main.xml

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

    <EditText
        android:id="@+id/plusone"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:inputType="none" />

    <TextView
        android:id="@+id/symbol"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

    <EditText
        android:id="@+id/plustwo"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:inputType="none" />

    <Button
        android:id="@+id/count"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

</LinearLayout>