3. 編輯主程式

編輯src→com.demo.android.bmi→Main.java

完整API查詢：http://developer.android.com/reference/packages.html

package com.demo.android.bmi;

import java.text.DecimalFormat;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class Main extends Activity {
    private Button button_calc;
	private EditText field_height;
	private EditText field_weight;
	private TextView view_result;
	private TextView view_good_weight;
	private TextView  view_suggest;


	/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        findviews();
        setListensers();
        
    }

	private void findviews() {
		button_calc = (Button)findViewById(R.id.submit);
		field_height=(EditText)findViewById(R.id.height);
		field_weight=(EditText)findViewById(R.id.weight);
		view_result=(TextView)findViewById(R.id.result);
		view_suggest=(TextView)findViewById(R.id.suggest);
		view_good_weight=(TextView)findViewById(R.id.goodWeight);
		
	}
	
    private void setListensers() {
    	button_calc.setOnClickListener(calcBMI);

	}


	private  OnClickListener calcBMI = new OnClickListener(){
    	public void onClick(View v){
    		DecimalFormat nf = new DecimalFormat("0.0");
    		try{
        		
        		double height = Double.parseDouble( field_height.getText().toString() ) / 100;
        		double weight = Double.parseDouble( field_weight.getText().toString() );
        		double BMI=weight / ( height * height );
        		
        		view_result.setText( getText( R.string.bmi_result  ) + nf.format(BMI) );

        		double min_weight=20 * ( height * height );
        		double max_weight=25 * ( height * height );
        		view_good_weight.setText(getText(R.string.goodWeight) + nf.format(min_weight) +"~" + nf.format(max_weight));
        		
        		//建議    		
        		if(BMI > 25){
        			 view_suggest.setText(R.string.advice_heavy);
        		}else if(BMI < 20){
        			view_suggest.setText(R.string.advice_light);
        		}else{
        			view_suggest.setText(R.string.advice_average);
        		}
        		
        		openOptionsDialog();
    			
    		}catch(Exception obj){
    			
    			//隱現視窗，LENGTH_SHORT短訊息
    			Toast.makeText(Main.this, R.string.errMsg1, Toast.LENGTH_SHORT).show();
    			
    		}
    	}

		private void openOptionsDialog() {
			//建立具名實體，會佔記憶體到關閉程式為止 Main.this 是指建立在目前畫面之上
			/*
			AlertDialog.Builder dialog = new  AlertDialog.Builder(Main.this);
			dialog.setTitle("關於BMI App");
			dialog.setMessage("這只是我練習的一個小App啦~");
			dialog.show();
			*/
			
			//建立對話框匿名實體，結束就釋放記憶體，適合短暫秀出
			
			new  AlertDialog.Builder(Main.this)
			.setTitle(R.string.aboutTitle)
			.setMessage(R.string.aboutContent)
			.setPositiveButton(R.string.label_ok,
					new DialogInterface.OnClickListener() {
						public void onClick(DialogInterface dialog, int which) {
							
						}
					})
			.setNegativeButton(R.string.label_homepage,
					new DialogInterface.OnClickListener() {
						public void onClick(DialogInterface dialog, int which) {
							//連到某個網址，地圖可用 geo: 經度 , 緯度，電話tel:2130669
							// Uri.parse不支援資源識別符號，所以用getString()取得實際值
							Uri uri = Uri.parse( getString( R.string.label_homepage_url ) );
							//"意圖"實體，ACTION_VIEW 根據不同檔案類型，自動執行關聯軟體
							//ACTION_DIAL可撥電話
							Intent intent = new Intent(Intent.ACTION_VIEW , uri);
							//執行意圖
							startActivity(intent);
						}
					})		
			.show();
			
		}    	
    };
}