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

public class MainActivity extends Activity {

    private TextView factor;
    private EditText factor1;
    private EditText factor2;
    private Button result;

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

        factor = (TextView)findViewById(R.id.factor);
        factor1 = (EditText)findViewById(R.id.factor1);
        factor2 = (EditText)findViewById(R.id.factor2);
        result = (Button)findViewById(R.id.result);
        factor.setText(R.string.factor);
        result.setText(R.string.result);
        //綁定一個(gè)監(jiān)聽(tīng)器到該按鈕
        result.setOnClickListener(new onResultClickListener());
    }

    //該函數(shù)其實(shí)是一個(gè)回調(diào)函數(shù)，但在系統(tǒng)中按下了menu按鈕時(shí)會(huì)自動(dòng)調(diào)用這個(gè)函數(shù)
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        //要在返回代碼之前加入
        menu.add(0, 1, 1, R.string.exit);
        menu.add(0, 2, 2, R.string.about);
        return super.onCreateOptionsMenu(menu);   
    }

    //菜單項(xiàng)選擇函數(shù)重寫
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if( 1 == item.getItemId() )
   finish();
        return super.onOptionsItemSelected(item);
    }

    //創(chuàng)建一個(gè)監(jiān)聽(tīng)器
    class onResultClickListener implements OnClickListener{

        public void onClick(View v) {
   //獲取2個(gè)edit輸入的數(shù)字
   String factor1_str = factor1.getText().toString();
   String factor2_str = factor2.getText().toString();
   //建立intent，并將數(shù)據(jù)傳入，且激活ResultActivity
   Intent intent = new Intent();
   intent.putExtra("factor1", factor1_str);
   intent.putExtra("factor2", factor2_str);
   intent.setClass(MainActivity.this, ResultActivity.class);
   //啟動(dòng)intent
   MainActivity.this.startActivity(intent);
        }

    }
}

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

public class ResultActivity extends Activity {

    private TextView result_dis;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_result);

        result_dis = (TextView)findViewById(R.id.result_view);
        Intent intent = getIntent();
        String factor_str1 = intent.getStringExtra("factor1");
        String factor_str2 = intent.getStringExtra("factor2");
        //java中將字符串轉(zhuǎn)換成整數(shù)的語(yǔ)法
        int factor_int1 = Integer.parseInt(factor_str1);
        int factor_int2 = Integer.parseInt(factor_str2);
        int result = factor_int1 * factor_int2;
        //java運(yùn)算中只要2者其中有一個(gè)為字符型，則會(huì)自動(dòng)將另一個(gè)也轉(zhuǎn)換成字符串
        result_dis.setText(result + "");

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_result, menu);
        return true;
    }
}

activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/factor1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        /> 
    <TextView
        android:id="@+id/factor"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />   
    <EditText
        android:id="@+id/factor2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />
    <Button
        android:id="@+id/result"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />

</LinearLayout>

    <TextView
        android:id="@+id/result_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
    ></TextView>

</RelativeLayout>