Eclipse 中的错误：使用 EditText 未定义运算符，双精度

Question

我正在尝试制作一个简单的小费计算器，并有一个 EditText 文本字段，您可以在其中输入您的总账单金额，然后单击您要在小费中计算的百分比按钮（例如 10%），然后单击该 % 按钮的 onClickListener 将计算提示并将结果放入自身下方的不同 TextView 字段中。

但是，我知道我必须将我的总帐单的 EditText 从一个字符串更改为一个双字节，并包含为此的代码，但是当我尝试将总帐单乘以 10% 的小费时，我仍然得到错误.为什么？

这是我的代码：

package com.example.nonitips;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    public EditText totalBill;
    public double billWithTip;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        totalBill = (EditText)findViewById(R.id.totalBill);
    }

    public void onTen (View v) {
        Toast.makeText(this, "Tipping at 10%", Toast.LENGTH_SHORT).show();

        totalBill.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double bill = Double.parseDouble(totalBill.getText().toString());
                bill = (totalBill * 0.10) + totalBill; //Error on this line.
            }
        });

    }

    public void onFifteen (View v) {
        Toast.makeText(this, "Tipping at 15%", Toast.LENGTH_SHORT).show();
    }

    public void onTwenty (View v) {
        Toast.makeText(this, "Tipping at 20%", Toast.LENGTH_SHORT).show();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

Answer 1

更改您的 EditText 点击代码：

     totalBill.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        double bill = Double.parseDouble(totalBill.getText().toString());
                        billWithTip= (bill * 0.10) + billWithTip; 

     Toast.makeText(this, "Updated billWithTip"+billWithTip, Toast.LENGTH_SHORT).show();
billWithTip.setText(String.valueOf(billWithTip));
                    }
                });

Double 到 String 的转换示例：

double total = 44; 
String total2 = String.valueOf(total);

Answer 2

您正在尝试将多个 EditText 与 double 值。使用以下代码。

totalBill.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double bill = Double.parseDouble(totalBill.getText().toString());
                billWithTip= (bill * 0.10) + billWithTip; 
            }
        });

Answer 3

        try this one..
        totalBill.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                     //   double bill = Double.parseDouble(totalBill.getText().toString());
                      //  bill = (totalBill * 0.10) + totalBill; //Error on this line.



    try {
    String bills= totalBill.getText().toString();
  Double protein = Double.parseDouble(bills); // Make use of autoboxing.It's also easier to read.
    } catch (NumberFormatException e) {
      // p did not contain a valid double
    }

        if(protein == null || protein.isEmpty()) {

          bill = 0.0;

        } else {

          bills= Double.parseDouble(noKids.getText().toString());
        Double protein = Double.parseDouble(bills);
          bill = (protein * 0.10) + protein ;
        }
                    }
                });

    thank you..

Answer 4

试试这个

totalBill.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            double bill = Double.parseDouble(totalBill.getText().toString());
            bill = (bill  * 0.10) + bill ); 
        }
    });