我正在使用Android Studio，即使代码中没有错误，我的应用也会在打开模拟器时崩溃。
MainActivity.java
package com.example.ss.flashcash;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;
import java.text.DecimalFormat;
public class MainActivity extends ActionBarActivity {
double money;
double convert;
EditText txtMoney;
RadioButton radEuros, radPesos, radRupees;
TextView txtResult;
Button btnComputeCost;
DecimalFormat hundredth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txtMoney = (EditText) findViewById(R.id.txtMoney);
radEuros = (RadioButton) findViewById(R.id.radEuros);
radPesos = (RadioButton) findViewById(R.id.radPesos);
radRupees = (RadioButton) findViewById(R.id.radRupees);
btnComputeCost = (Button) findViewById(R.id.btnComputeCost);
txtResult = (TextView) findViewById(R.id.txtResult);
btnComputeCost.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculate();
}
});
}
public void calculate()
{
hundredth = new DecimalFormat("#.##");
money = Double.parseDouble(txtMoney.getText().toString());
if (radEuros.isChecked())
{
if (money < 100000)
{
convert = money * .92;
txtResult.setText("$" + hundredth.format(convert));
}
else Toast.makeText(this, "Enter less than 100,000", Toast.LENGTH_LONG).show();
}
if (radPesos.isChecked())
{
if (money < 100000)
{
convert = money * 15.02;
txtResult.setText("$" + hundredth.format(convert));
}
else Toast.makeText(this, "Enter less than 100,000", Toast.LENGTH_LONG).show();
}
if (radRupees.isChecked())
{
if (money < 100000)
{
convert = money * 62.32;
txtResult.setText("$" + hundredth.format(convert));
}
else Toast.makeText(this, "Enter less than 100,000", Toast.LENGTH_LONG).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.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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
activity_main.xml中
<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Currency Converter"
android:id="@+id/txtHeader"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="54dp"
android:typeface="sans"/>
<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/radioGroup"
android:layout_centerVertical="true">
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Euros"
android:id="@+id/radEuros"
android:layout_below="@+id/txtHeader"
android:layout_alignLeft="@+id/txtHeader"
android:layout_alignStart="@+id/txtHeader"
android:layout_marginTop="129dp"
android:checked="false"
android:textColor="#FF0000"
android:textSize="30dp" />
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Pesos"
android:id="@+id/radPesos"
android:layout_below="@+id/radEuros"
android:layout_alignLeft="@+id/radEuros"
android:layout_alignStart="@+id/radEuros"
android:checked="false"
android:textColor="#19FF19"
android:textSize="30dp" />
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Rupees"
android:id="@+id/radRupees"
android:checked="false"
android:layout_below="@+id/radPesos"
android:layout_alignLeft="@+id/radPesos"
android:layout_alignStart="@+id/radPesos"
android:textColor="#FFFF19"
android:textSize="30dp" />
</RadioGroup>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/txtMoney"
android:layout_above="@+id/radioGroup"
android:layout_centerHorizontal="true"
android:hint="Enter $Amount"
android:typeface="sans"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="CONVERT"
android:id="@+id/btnComputeCost"
android:layout_marginTop="45dp"
android:layout_below="@+id/radioGroup"
android:layout_toLeftOf="@+id/txtHeader"
android:layout_toStartOf="@+id/txtHeader" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/txtResult"
android:layout_alignParentBottom="true"
android:layout_alignLeft="@+id/btnComputeCost"
android:layout_alignStart="@+id/btnComputeCost"
android:typeface="sans"/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:src="@drawable/money3"
android:layout_alignBottom="@+id/btnComputeCost"
android:layout_toRightOf="@+id/radioGroup"
android:layout_toEndOf="@+id/radioGroup" />
</RelativeLayout>
的AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.ss.flashcash" >
<application
android:allowBackup="true"
android:icon="@drawable/moneypng"
android:label="@string/app_name"
android:theme="@style/AppTheme"
android:background="@color/blue">
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
logcat的：
03-22 22:48:25.005 1929-1929/com.example.ss.flashcash I/art﹕ Not late-enabling -Xcheck:jni (already on)
03-22 22:48:29.458 1929-1941/com.example.ss.flashcash I/art﹕ Background sticky concurrent mark sweep GC freed 2956(243KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 2045KB/2045KB, paused 1.594ms total 285.202ms
03-22 22:48:29.559 1929-1929/com.example.ss.flashcash D/AndroidRuntime﹕ Shutting down VM
03-22 22:48:29.559 1929-1929/com.example.ss.flashcash E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.ss.flashcash, PID: 1929
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ss.flashcash/com.example.ss.flashcash.MainActivity}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
at com.example.ss.flashcash.MainActivity.onCreate(MainActivity.java:30)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
非常感谢所有的帮助。
答案 0 :(得分：3)
可能会ClassCastException，因为这里：
txtMoney = (EditText) findViewById(R.id.txtMoney);
txtMoney是TextView的ID，但是尝试投放EditText
答案 1 :(得分：0)
查看您的布局文件。你写了：
...
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/txtMoney"
android:layout_above="@+id/radioGroup"
android:layout_centerHorizontal="true"
android:hint="Enter $Amount"
android:typeface="sans"/>
...
现在在您的活动中，您的代码：
txtMoney = (EditText) findViewById(R.id.txtMoney);
正在筹集ClassCastException，因为您正试图将TextView投放到EditText。
我希望你明白这一点。