Slide 10.16: Dynamic checkboxes: Java source code (cont.)

Dynamic Checkboxes: Java Code (Cont.)

CheckBox checkBox1 = new CheckBox( getApplicationContext( ) );: The method getApplicationContext returns the context of the single, global Application object of the current process, whereas this is usually associated with to the activity and can be destroyed if the activity is destroyed—there may be multiple activities (more than likely) with a single application.; The method setID sets the identifier for this view. The identifier does not have to be unique in this view’s hierarchy. The identifier should be a positive number.; The method setText sets the string value of the view.; The method setTextColor sets the text color for all the states (normal, selected, focused) to be this color. The Color class defines methods for creating and converting color ints. Colors are represented as packed ints, made up of 4 bytes: alpha, red, green, blue. For example, the black color is the constant value: -16777216 (0xFF000000).; The method addView adds a child view. If no layout parameters are already set on the child, the default parameters for this ViewGroup are set on the child.

DynamicCheckbox/app/src/main/java/com/ecs/wenchen/dynamiccheckbox/MainActivity.java

package com.ecs.wenchen.dynamiccheckbox;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.EditText;
import android.graphics.Color;

public class MainActivity extends Activity {
  LinearLayout linearBox;
  CheckBox     checkBox, checkBox1;

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

    linearBox = (LinearLayout) findViewById( R.id.linearBox );
    final EditText number = (EditText) findViewById( R.id.number );
    final EditText title  = (EditText) findViewById( R.id.title );
    final Button   button = (Button)   findViewById( R.id.add );

    button.setOnClickListener( new View.OnClickListener( ) {
      public void onClick( View v ) {
        checkBox1 = new CheckBox( getApplicationContext( ) );
        checkBox1.setId( Integer.parseInt( number.getText( ).toString( ) ) );
        checkBox1.setText( title.getText( ).toString( ) );
        checkBox1.setTextColor( Color.BLACK );
        checkBox1.setOnClickListener( getOnClickDoSomething( checkBox1 ) );
        linearBox.addView( checkBox1 );
      }
    } );

    final LinkedHashMap<String, String>
      alphabet = new LinkedHashMap<String, String>( );
    alphabet.put( "260", ".NET" );
    alphabet.put( "370", "Computer Architecture" );

    Set<?> set = alphabet.entrySet( );
    // Get an iterator.
    Iterator<?> i = set.iterator( );
    // Display elements.
    while ( i.hasNext( ) ) {
      @SuppressWarnings( "rawtypes" )
      Map.Entry me = ( Map.Entry ) i.next( );
      checkBox     = new CheckBox( this );
      checkBox.setId( Integer.parseInt( me.getKey( ).toString( ) ) );
      checkBox.setText( me.getValue( ).toString( ) );
      checkBox.setOnClickListener( getOnClickDoSomething( checkBox ) );
      linearBox.addView( checkBox );
    }
  }

  View.OnClickListener getOnClickDoSomething( final Button button ) {
    return new View.OnClickListener( ) {
      public void onClick( View v ) {
        final TextView tvView = (TextView) findViewById( R.id.textView3 );
        tvView.setText( button.getId( ) + ": " + button.getText( ).toString( ) );
      }
    };
  }
}