深入浅出Android：传送数据到新的Activity(BMI)-优快云博客

本文介绍了一个简单的BMI计算器Android应用实现过程，包括MainActivity与Report两个页面的交互逻辑。该应用通过输入身高与体重计算BMI指数，并根据结果提供健康建议。

1、

MainActivity.java

  1 package example.bmi;
  2 
  3 import java.text.DecimalFormat;
  4 
  5 import android.net.Uri;
  6 import android.os.Bundle;
  7 import android.app.Activity;
  8 import android.app.AlertDialog;
  9 import android.content.ClipData.Item;
 10 import android.content.DialogInterface;
 11 import android.content.Intent;
 12 import android.view.Menu;
 13 import android.view.MenuItem;
 14 import android.view.View;
 15 import android.view.View.OnClickListener;
 16 import android.widget.Button;
 17 import android.widget.EditText;
 18 import android.widget.TextView;
 19 
 20 @SuppressWarnings("unused")
 21 public class MainActivity extends Activity {
 22 
 23     @Override
 24     protected void onCreate(Bundle savedInstanceState) {
 25         super.onCreate(savedInstanceState);
 26         setContentView(R.layout.activity_main);
 27         
 28         findViews();
 29         setListensers();
 30     }
 31     private Button button_calc;
 32     private EditText field_height;
 33     private EditText field_weight;
 34  //   private TextView view_result;
 35  //   private TextView view_suggest;
 36     private void findViews()
 37     {
 38         button_calc=(Button)findViewById(R.id.submit);
 39         field_height=(EditText)findViewById(R.id.height);
 40         field_weight=(EditText)findViewById(R.id.weight);
 41     //    view_result=(TextView)findViewById(R.id.result);
 42     //    view_suggest=(TextView)findViewById(R.id.suggest);
 43     }
 44     private void setListensers()
 45     {
 46         button_calc.setOnClickListener(calcBMI);
 47     }
 48     private Button.OnClickListener calcBMI=new Button.OnClickListener()
 49     {
 50         public void onClick(View v)
 51         {
 52             //switch to report page
 53             Intent intent = new Intent();
 54             intent.setClass(MainActivity.this, Report.class);
 55             startActivity(intent);
 56             Bundle bundle = new Bundle();
 57             bundle.putString("KEY_HEIGHT", field_height.getText().toString());
 58             bundle.putString("KEY_WEIGHT", field_weight.getText().toString());
 59             intent.putExtras(bundle);
 60             startActivity(intent);
 61         }    
 62     };
 63     protected static final int MENU_ABOUT = Menu.FIRST;
 64     protected static final int MENU_Quit = Menu.FIRST+1;
 65     
 66     @Override
 67     public boolean onCreateOptionsMenu(Menu menu)
 68     {
 69         super.onCreateOptionsMenu(menu);
 70         menu.add(0, MENU_ABOUT, 0, "关于");
 71         menu.add(0, MENU_Quit, 0, "结束");
 72         return true;
 73     }
 74     public boolean onOptionsItemSelected(MenuItem item)
 75     {
 76         super.onOptionsItemSelected(item);
 77         switch(item.getItemId())
 78         {
 79         case MENU_ABOUT:
 80             openOptionsDialog();
 81             break;
 82         case MENU_Quit:
 83             finish();
 84             break;
 85         }
 86         return true;
 87     }
 88     private void openOptionsDialog()
 89     {
 90         new AlertDialog.Builder(MainActivity.this)
 91             .setTitle(R.string.about_title)
 92             .setMessage(R.string.about_msg)
 93             .setPositiveButton(R.string.ok_label,
 94                     new DialogInterface.OnClickListener() {
 95                 public void onClick(
 96                         DialogInterface dialoginterface,int i){
 97                    }
 98                 
 99                 })
100             .setNegativeButton(R.string.homepage_label,
101                     new DialogInterface.OnClickListener() {
102                         
103                         @Override
104                         public void onClick(DialogInterface dialog, int which) {
105                             Uri uri=Uri.parse(getString(R.string.homepage_uri));
106                             Intent intent=new Intent(Intent.ACTION_VIEW,uri);
107                             startActivity(intent);
108                         }
109                     })
110             .show();
111     }
112 
113   /*  @Override
114     public boolean onCreateOptionsMenu(Menu menu) {
115         // Inflate the menu; this adds items to the action bar if it is present.
116         getMenuInflater().inflate(R.menu.activity_main, menu);
117         return true;
118     }
119     */
120 }

2、

report.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     xmlns:tools="http://schemas.android.com/tools"
 4     android:layout_width="match_parent"
 5     android:layout_height="match_parent"
 6     >
 7 
 8     <TextView android:id="@+id/result"
 9         android:layout_width="fill_parent"
10         android:layout_height="wrap_content"
11         android:text="" 
12         />
13     <TextView android:id="@+id/suggest"
14         android:layout_width="fill_parent"
15         android:layout_height="wrap_content"
16         android:text=""
17         android:layout_below="@id/result"
18         />
19     <Button android:id="@+id/report_back"
20         android:layout_width="wrap_content"
21         android:layout_height="wrap_content"
22         android:text="@string/report_back"
23         android:layout_below="@id/suggest"
24         />
25 </RelativeLayout>

3、

Report.java

 1 package example.bmi;
 2 
 3 import java.text.DecimalFormat;
 4 import android.app.Activity;
 5 import android.os.Bundle;
 6 import android.widget.Button;
 7 import android.widget.TextView;
 8 import android.view.View;
 9 
10 
11 public class Report extends Activity {
12     @Override
13     protected void onCreate(Bundle savedInstanceState) {
14         super.onCreate(savedInstanceState);
15         setContentView(R.layout.report);
16         
17         findViews();
18         setListeners();
19         showResults();
20     }
21     private Button button_back;
22     private TextView view_result;
23     private TextView view_suggest;
24     
25     private void findViews()
26     {
27         button_back=(Button)findViewById(R.id.report_back);
28         view_result=(TextView)findViewById(R.id.result);
29         view_suggest=(TextView)findViewById(R.id.suggest);
30     }
31     private void setListeners(){
32         button_back.setOnClickListener(backMain);
33     }
34     private Button.OnClickListener backMain = new Button.OnClickListener()
35     {
36         public void onClick(View v)
37         {
38             Report.this.finish();
39         }
40     };
41     private void showResults()
42     {
43         DecimalFormat nf=new DecimalFormat("0.00");
44         
45         Bundle bundle = this.getIntent().getExtras();
46         double height = Double.parseDouble(bundle.getString("KEY_HEIGHT"))/100;
47         double weight = Double.parseDouble(bundle.getString("KEY_WEIGHT"));
48         double BMI = weight/(height*height);
49         view_result.setText(getString(R.string.bmi_result)+nf.format(BMI));
50         //give health advice
51         if(BMI>25)
52         {
53             view_suggest.setText(R.string.advice_heavy);
54         }
55         else if(BMI<20)
56         {
57             view_suggest.setText(R.string.advice_light);
58         }
59         else
60         {
61             view_suggest.setText(R.string.advice_average);
62         }
63     }
64 }