Step 05 - Research + New Control Layout

    We need radio buttons, some sort of selection/combo box + a progress bar. These can be found in various locations in the pallette:

    Step 05 - 图2

    … and we can bring in three fields into the class:

    2.   private ProgressBar  progressBar;
    3.   private NumberPicker amountPicker;

    We can also open up three pages of documentation - which we can reverse engineer from the package/class names:

    Note this time we have gone to the Activity class before actually creating the controls. We should do this now - and remember to use the same names (for the IDs) as we create the controls.

    Getting the layout +id names as shown above may take some practice. However, it is an essential skill to get on top of, even it it takes a lot of trial and error.

    For reference purposes (try to do it yourself first!), these are the relevant generated xml files:

    1. <?xml version="1.0" encoding="utf-8"?>
    2. <resources>
    4.     <string name="app_name">Donation</string>
    5.     <string name="action_settings">Settings</string>
    6.     <string name="donateTitle">Welcome Homer</string>
    7.     <string name="donateSubtitle">Please give generously</string>
    8.     <string name="donateButton">Button</string>
    9.     <string name="PayPal">PayPal</string>
    10.     <string name="Direct">Direct</string>
    12. </resources>

    If we have our naming conventions right - then we can bind to these new controls in onCreate:

    1. package com.example.donation;
    3. import android.os.Bundle;
    4. import android.util.Log;
    6. import android.view.View;
    7. import android.widget.Button;
    8. import android.widget.RadioGroup;
    9. import android.widget.NumberPicker;
    10. import android.widget.ProgressBar;
    13. public class Donate extends Activity
    14. {
    15.   private Button       donateButton;
    16.   private RadioGroup   paymentMethod;
    17.   private ProgressBar  progressBar;
    18.   private NumberPicker amountPicker;
    20.   @Override
    21.   protected void onCreate(Bundle savedInstanceState)
    22.   {
    23.     super.onCreate(savedInstanceState);
    24.     setContentView(R.layout.activity_donate);
    25.     donateButton  = (Button)       findViewById(R.id.donateButton);
    26.     paymentMethod = (RadioGroup)   findViewById(R.id.paymentMethod);
    27.     progressBar   = (ProgressBar)  findViewById(R.id.progressBar);
    28.     amountPicker  = (NumberPicker) findViewById(R.id.amountPicker);
    30.     amountPicker.setMinValue(0);
    31.     amountPicker.setMaxValue(1000);
    32.   }
    34.   @Override
    35.   public boolean onCreateOptionsMenu(Menu menu)
    36.   {
    37.     getMenuInflater().inflate(R.menu.donate, menu);
    38.     return true;
    39.   }
    41.   public void donateButtonPressed (View view) 
    42.   {
    43.     Log.v("Donate", "Donate Pressed!");
    45. }