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安卓——主要错误：无法启动活动组件信息

javaandroidfatal-errorclasscastexceptionruntimeexception
5
我的问题是，当我在安卓模拟器上运行我的应用程序时，应用程序启动后很快就会崩溃，并显示弹出窗口："Unfortunately, TipCalculator has stopped." 我已经查看了代码，也在互联网上进行了彻底的搜索。是的，我是一个新手在安卓开发方面。我查看了由LogCat生成的错误，但不知道问题所在以及根据收到的错误在哪里找到它。
这是我的代码:
TipCalc.java package com.troysantry.tipcalculator;
import android.os.Bundle;
import android.app.Activity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.widget.EditText;

public class TipCalc extends Activity {

    public static final String TOTAL_BILL = "TOTAL_BILL";
    public static final String CURRENT_TIP = "CURRENT_TIP";
    public static final String BILL_WITHOUT_TIP = "BILL_WITHOUT_TIP";

    public double billBeforeTip;
    public double tipAmount;
    public double finalBill;

    EditText txtBillBeforeTip;
    EditText txtTipAmount;
    EditText txtFinalBill;

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

        if(savedInstanceState==null){

            billBeforeTip=0.0;
            tipAmount=0.15;
            finalBill=0.0;
        }
        else{

            billBeforeTip=savedInstanceState.getDouble(BILL_WITHOUT_TIP);
            tipAmount=savedInstanceState.getDouble(CURRENT_TIP);
            finalBill=savedInstanceState.getDouble(TOTAL_BILL);

        }
            txtBillBeforeTip = (EditText) findViewById(R.id.txtBill);
            txtTipAmount=(EditText) findViewById(R.id.txtTip);
            txtFinalBill=(EditText) findViewById(R.id.txtFinal);

            txtBillBeforeTip.addTextChangedListener(billBeforeTipListener);     
    }

    private TextWatcher billBeforeTipListener = new TextWatcher(){

        @Override
        public void afterTextChanged(Editable arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {

            try{
                billBeforeTip = Double.parseDouble(s.toString());

            }
            catch(NumberFormatException e){
                billBeforeTip=0.0;
            }

            UpdateTipAndFinalBill();    
        }
    };

    protected void onSaveInstanceState(Bundle outState){

        super.onSaveInstanceState(outState);

        outState.putDouble(TOTAL_BILL, finalBill);
        outState.putDouble(CURRENT_TIP, tipAmount);
        outState.putDouble(BILL_WITHOUT_TIP, billBeforeTip);

    }

    private void UpdateTipAndFinalBill(){
        double tipAmount = Double.parseDouble(txtTipAmount.getText().toString());

        double finalBill = billBeforeTip + (billBeforeTip*tipAmount);

        txtFinalBill.setText(String.format("%.02f",finalBill));

    }
    @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_calc, menu);
        return true;
    }

}

activity_tip_calc.xml

<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=".TipCalc" >

    <TextView
        android:id="@+id/tvBill"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="19dp"
        android:layout_marginTop="14dp"
        android:text="@string/bill_text_view" />

    <TextView
        android:id="@+id/tvFinal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/txtBill"
        android:layout_below="@+id/txtBill"
        android:layout_marginRight="24dp"
        android:layout_marginTop="18dp"
        android:text="@string/final_text_view" />

    <EditText
        android:id="@+id/txtFinal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/tvFinal"
        android:layout_alignBottom="@+id/tvFinal"
        android:layout_alignRight="@+id/txtTip"
        android:layout_marginRight="25dp"
        android:ems="6"
        android:inputType="numberDecimal"
        android:text="@string/final_bill_edit_text" />

    <TextView
        android:id="@+id/tvTip"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/tvFinal"
        android:layout_centerHorizontal="true"
        android:text="@string/tip_text_view" />

    <EditText
        android:id="@+id/txtTip"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/tvTip"
        android:layout_alignBottom="@+id/tvTip"
        android:layout_toRightOf="@+id/tvTip"
        android:ems="5"
        android:inputType="numberDecimal"
        android:text="@string/tip_edit_text"
        android:textSize="16sp" />

    <EditText
        android:id="@+id/txtBill"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/tvBill"
        android:layout_alignBottom="@+id/tvBill"
        android:layout_toRightOf="@+id/tvBill"
        android:ems="5"
        android:inputType="numberDecimal"
        android:text="@string/bill_edit_text"
        android:textSize="16sp" />

</RelativeLayout>

LogCat（日志）
11-04 01:24:10.403: D/AndroidRuntime(1050): Shutting down VM
11-04 01:24:10.403: W/dalvikvm(1050): threadid=1: thread exiting with uncaught exception (group=0x41465700)
11-04 01:24:10.543: E/AndroidRuntime(1050): FATAL EXCEPTION: main
11-04 01:24:10.543: E/AndroidRuntime(1050): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.troysantry.tipcalculator/com.troysantry.tipcalculator.TipCalc}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.os.Looper.loop(Looper.java:137)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.ActivityThread.main(ActivityThread.java:5103)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at java.lang.reflect.Method.invokeNative(Native Method)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at java.lang.reflect.Method.invoke(Method.java:525)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at dalvik.system.NativeStart.main(Native Method)
11-04 01:24:10.543: E/AndroidRuntime(1050): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
11-04 01:24:10.543: E/AndroidRuntime(1050):     at com.troysantry.tipcalculator.TipCalc.onCreate(TipCalc.java:45)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.Activity.performCreate(Activity.java:5133)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-04 01:24:10.543: E/AndroidRuntime(1050):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
11-04 01:24:10.543: E/AndroidRuntime(1050):     ... 11 more
11-04 01:29:11.177: I/Process(1050): Sending signal. PID: 1050 SIG: 9
11-04 01:31:32.080: D/AndroidRuntime(1109): Shutting down VM
11-04 01:31:32.080: W/dalvikvm(1109): threadid=1: thread exiting with uncaught exception (group=0x41465700)
11-04 01:31:32.194: E/AndroidRuntime(1109): FATAL EXCEPTION: main
11-04 01:31:32.194: E/AndroidRuntime(1109): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.troysantry.tipcalculator/com.troysantry.tipcalculator.TipCalc}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.os.Looper.loop(Looper.java:137)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.ActivityThread.main(ActivityThread.java:5103)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at java.lang.reflect.Method.invokeNative(Native Method)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at java.lang.reflect.Method.invoke(Method.java:525)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at dalvik.system.NativeStart.main(Native Method)
11-04 01:31:32.194: E/AndroidRuntime(1109): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
11-04 01:31:32.194: E/AndroidRuntime(1109):     at com.troysantry.tipcalculator.TipCalc.onCreate(TipCalc.java:44)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.Activity.performCreate(Activity.java:5133)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-04 01:31:32.194: E/AndroidRuntime(1109):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
11-04 01:31:32.194: E/AndroidRuntime(1109):     ... 11 more
11-04 01:36:33.195: I/Process(1109): Sending signal. PID: 1109 SIG: 9
11-04 02:11:09.684: D/AndroidRuntime(1167): Shutting down VM
11-04 02:11:09.684: W/dalvikvm(1167): threadid=1: thread exiting with uncaught exception (group=0x41465700)
11-04 02:11:09.855: E/AndroidRuntime(1167): FATAL EXCEPTION: main
11-04 02:11:09.855: E/AndroidRuntime(1167): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.troysantry.tipcalculator/com.troysantry.tipcalculator.TipCalc}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.os.Looper.loop(Looper.java:137)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.ActivityThread.main(ActivityThread.java:5103)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at java.lang.reflect.Method.invokeNative(Native Method)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at java.lang.reflect.Method.invoke(Method.java:525)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at dalvik.system.NativeStart.main(Native Method)
11-04 02:11:09.855: E/AndroidRuntime(1167): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
11-04 02:11:09.855: E/AndroidRuntime(1167):     at com.troysantry.tipcalculator.TipCalc.onCreate(TipCalc.java:44)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.Activity.performCreate(Activity.java:5133)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-04 02:11:09.855: E/AndroidRuntime(1167):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
11-04 02:11:09.855: E/AndroidRuntime(1167):     ... 11 more
4
在从“项目”菜单中清除项目后，请尝试运行应用程序。 - ρяσѕρєя K
你能否尝试清理并构建项目，然后重新启动应用程序？ - Alexis C.
我同意@ρяσѕρєяK的观点，我尝试了你的代码，看起来运行良好。 - blitzen12
4个回答
4

由于： java.lang.ClassCastException: android.widget.TextView 无法转换为 android.widget.EditText

在 com.troysantry.tipcalculator.TipCalc.onCreate(TipCalc.java:45) 处发生。

LogCat 是您的好朋友。

您的布局中有一个 TextView，但是在代码中，您试图将其转换为 EditText。

重新阅读您的代码后，似乎没有问题，请尝试清理您的项目。

项目 -> 清理

3
R.id.txtBill, R.id.txtTip, R.id.txtFinal 是三个 EditText 的 ID。 - Raghunandan
请检查TipCalc.java文件中的第45行。 - harris
3

从我的经验来看，这是一个与RelativeLayout有关的问题。我不知道具体问题出在哪里，但以下两个解决方案适用于我。

  1. 清理你的项目并重新运行。如果这样仍然不成功，那么
  2. 将RelativeLayout改为LinearLayout（这需要删除相关属性，并进行一些布局的调整）。
将RelativeLayout更改为LinearLayout。相对布局有什么问题吗？没有必要使用它。清理并构建应该可以解决问题。 - Raghunandan
@Raghunandan: 是的，它应该可以工作。但是我不知道，有时候它不起作用。 - Nizam
@Nizam 你是对的... 清除(clean)没有起作用，但是将相对(relative)改为线性(linear)解决了问题。 - Madhav Kishore
0

你的布局中可能有一个 TextView，并且在代码中使用了一个 EditText。

11-04 01:24:10.543: E/AndroidRuntime(1050): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
2
R.id.txtBill，R.id.txtTip，R.id.txtFinal都是editText的ID。我之前回答时犯了一个错误，后来删除了它。 - Raghunandan
0

我曾经遇到过同样的问题。通过运行ant clean; ant debug来解决了这个问题。

当我修改res/layout/main.xml并立即执行ant debug时，就会出现这个错误。

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