Question

正在研究一个基本的小费计算器并遇到以下程序崩溃。崩溃的日志是：

06-24 01:03:43.602: E/AndroidRuntime(27213): FATAL EXCEPTION: main
06-24 01:03:43.602: E/AndroidRuntime(27213): java.lang.NumberFormatException: Invalid double: "android.widget.EditText@41634f08"
06-24 01:03:43.602: E/AndroidRuntime(27213):    at java.lang.StringToReal.invalidReal(StringToReal.java:63)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at java.lang.StringToReal.initialParse(StringToReal.java:114)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at java.lang.StringToReal.parseDouble(StringToReal.java:263)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at java.lang.Double.parseDouble(Double.java:295)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at mkelleyjr.example.tippycalc.MainActivity$1.onClick(MainActivity.java:30)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at android.view.View.performClick(View.java:3540)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at android.view.View$PerformClick.run(View.java:14167)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at android.os.Handler.handleCallback(Handler.java:605)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at android.os.Handler.dispatchMessage(Handler.java:92)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at android.os.Looper.loop(Looper.java:137)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at android.app.ActivityThread.main(ActivityThread.java:4558)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at java.lang.reflect.Method.invokeNative(Native Method)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at java.lang.reflect.Method.invoke(Method.java:511)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-24 01:03:43.602: E/AndroidRuntime(27213):    at dalvik.system.NativeStart.main(Native Method)

activity_main.xml是：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="47dp"
    android:background="@android:color/holo_blue_light"
    android:text="Total Bill Amount"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:textColor="@android:color/holo_orange_dark" />

<TextView 
    android:id="@+id/res"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignRight="@+id/button1"
    android:layout_marginBottom="14dp"
    android:text="Result : "
    android:textAppearance="?android:attr/textAppearanceLarge" />


<Button 
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/res"
    android:layout_alignParentLeft="true"
    android:layout_alignRight="@+id/textView2"
    android:layout_marginBottom="34dp"
    android:background="@android:color/black"
    android:text="Calculate"
    android:textColor="@android:color/white" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/button1"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_marginBottom="96dp"
        android:background="@android:color/holo_green_dark"
        android:text="Enter Tip % :"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="@android:color/holo_red_dark" />

    <EditText
        android:id="@+id/bill_amt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@id/textView1"
        android:layout_marginTop="41dp"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <EditText
        android:id="@+id/bill_percent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/button1"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_marginBottom="22dp"
        android:ems="10" />

    </RelativeLayout>

MainActivity.java是：

package mkelleyjr.example.tippycalc;


import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


public class MainActivity extends Activity {

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

    final EditText amt = (EditText) findViewById(R.id.bill_amt);
    final EditText tip = (EditText) findViewById(R.id.bill_percent);
    final TextView result = (TextView) findViewById(R.id.res);

    Button calc = (Button) findViewById(R.id.button1);
            calc.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {

                    double amount = Double.parseDouble(amt.toString());
                    double tip_per = Double.parseDouble(tip.toString());
                    double tip_cal = (amount * tip_per) / 100;
                    result.setText("Result : " + Double.toString(tip_cal));

                }
            });

}

@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;
}

}

目前还不确定为什么它会崩溃说无效双。任何帮助是极大的赞赏！提前致谢！

Answer 1

 java.lang.NumberFormatException:
 Invalid double:"android.widget.EditText@41634f08"

您将editText Object的引用作为String的{{1}}方法parseDouble(String)和Double.parseDouble(amt.toString())传递，而不是

Double.parseDouble(tip.toString());

或

Double.parseDouble(editText.getText().toString())

代码。

Answer 2

 double amount = Double.parseDouble(amt.toString()); 
 double tip_per = Double.parseDouble(tip.toString());

错了

double amount = Double.parseDouble(amt.getText().toString());    
 double tip_per = Double.parseDouble(tip.getText().toString());

正确的方法

并添加

在EditText xml中

android:inputType="numberDecimal|numberSigned"

Answer 3

您以错误的方式从EditText获取文字。通过调用amt.toString()，您只需获得该类的默认Java字符串表示形式。正确的方法是：

EditText.getText().toString()

Answer 4

double amount = Double.parseDouble(amt.toString());

此处amt.toString()将返回amt EditText的字符串表示形式。我们需要在amt TextView中输入文本，因此请使用以下命令：

double amount = Double.parseDouble(amt.getText().toString());

Android Java NumberFormatException：提示计算器上的双倍无效

4 个答案: