Android Open Source - android-tip-calculator Tip Calculator

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From Project

Back to project page android-tip-calculator.

License

The source code is released under:

MIT License

Java Source Code

package com.gemmakbarlow.androidtipcalculator;
/*from   w w w .j a v  a  2  s  . com*/
import java.math.BigDecimal;
import java.util.Locale;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.view.Gravity;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class TipCalculator extends Activity {

  final int NUMBER_OF_DECIMAL_PLACES_FOR_USD = 2;
  final float TEN_PERCENT_FLOAT_MULTIPLIER = 0.10f;
  final float FIFTEEN_PERCENT_FLOAT_MULTIPLIER = 0.15f;
  final float TWENTY_PERCENT_FLOAT_MULTIPLIER = 0.20f;
  final float MIN_COST_VALUE = 1.0f;
  final float MAX_COST_VALUE = 1000000.0f;
  
  private EditText etEnterCost;
  private TextView tvFinalTip;
  private TextView tvOverallCost;
  private Toast invalidCostEnteredToast;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tip_calculator);
        
        // Initialize UI elements
        setEtEnterCost((EditText)findViewById(R.id.etTipInput));
        setTvFinalTip((TextView)findViewById(R.id.tvFinalTipValue));
        setTvOverallCost((TextView)findViewById(R.id.tvOverallValue));
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.tip_calculator, menu);
        return true;
    }

    private void calculateFinalTipFromPercentage(float percentageMultiplier) {
      
      // Only do something if a cost has been entered
      String cost = this.etEnterCost.getText().toString();
      if(cost.length() > 0) {
        
        float costValue = Float.parseFloat(cost);
        if(costValue > MIN_COST_VALUE && costValue <= MAX_COST_VALUE) {
          float tipValue = costValue * percentageMultiplier;
          float roundedTipValue = round(tipValue, NUMBER_OF_DECIMAL_PLACES_FOR_USD);
          
          String finalTipText = String.format(Locale.US, "$ \t%.2f USD", roundedTipValue); 
          this.tvFinalTip.setText(finalTipText);
          
          float roundedOverallValue = round(costValue + tipValue, NUMBER_OF_DECIMAL_PLACES_FOR_USD);
          String finalOverallText = String.format(Locale.US, "$ \t%.2f USD", roundedOverallValue);
          this.tvOverallCost.setText(finalOverallText);
        }
        else {
          showInvalidCostToast();
        }
      }
      else {
        showInvalidCostToast();
      }
    }
    
    
    /*
     * Helper Methods
     */
    
    private void resetInput() {
      this.etEnterCost.setText("");
      this.tvFinalTip.setText("");
      this.tvOverallCost.setText("");
      this.invalidCostEnteredToast.cancel();
    }
    
    private void showInvalidCostToast() {
      
      if(this.invalidCostEnteredToast == null) {
        invalidCostEnteredToast = new Toast(this);
      }
      else {
        invalidCostEnteredToast.cancel();
      }
      
      Context context = getApplicationContext();
      int duration = Toast.LENGTH_SHORT;
      invalidCostEnteredToast = Toast.makeText(context, R.string.tvInvalidValueEnteredString, duration);
      invalidCostEnteredToast.setGravity(Gravity.TOP|Gravity.CENTER, 0, 100);  
      invalidCostEnteredToast.show();
    }
    
    /**
     * From http://bit.ly/17aht8Y
     * 
     * @param valueToRound Value to round up or down
     * @param numDecimalPlaces Number of decimal places desired in result. 
     * @return float rounded to the correct number of decimal places
     */
    public static float round(float valueToRound, int numDecimalPlaces) {
        BigDecimal bd = new BigDecimal(Float.toString(valueToRound));
        bd = bd.setScale(numDecimalPlaces, BigDecimal.ROUND_HALF_UP);
        return bd.floatValue();
    }
    
    /*
     * Actions
     */
    
    /** Called when the user touches the button */
    public void btn10PercentTapped(View button) {
        calculateFinalTipFromPercentage(this.TEN_PERCENT_FLOAT_MULTIPLIER);
    }
    
    /** Called when the user touches the button */
    public void btn15PercentTapped(View button) {
      calculateFinalTipFromPercentage(this.FIFTEEN_PERCENT_FLOAT_MULTIPLIER);
    }
    
    
    /** Called when the user touches the button */
    public void btn20PercentTapped(View button) {
        calculateFinalTipFromPercentage(this.TWENTY_PERCENT_FLOAT_MULTIPLIER);
    }
    
    /** Called when the user touches the button */
    public void btnClearInputTapped(View button) {
        resetInput();
    }
   
    
    /*
     * Getters / Setters
     */

  public EditText getEtEnterCost() {
    return etEnterCost;
  }


  public void setEtEnterCost(EditText etEnterCost) {
    this.etEnterCost = etEnterCost;
  }


  public TextView getTvFinalTip() {
    return tvFinalTip;
  }


  public void setTvFinalTip(TextView tvFinalTip) {
    this.tvFinalTip = tvFinalTip;
  }


  public TextView getTvOverallCost() {
    return tvOverallCost;
  }


  public void setTvOverallCost(TextView tvOverallCost) {
    this.tvOverallCost = tvOverallCost;
  }
 
}

Java Source Code List

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