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我跟着this youtube tutorial 创建一个基本的计算应用程序。基本计算应用程序崩溃
我能在我的手机上调试它，它运行良好。但是，当我插入数字并按计算，应用程序冻结和崩溃。
这是我的布局：
<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/lblTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="66dp"
android:text="Basic Calculate"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/display"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/btnCalculate"
android:layout_below="@+id/btnCalculate"
android:layout_marginTop="23dp"
android:textAppearance="?android:attr/textAppearanceMedium" />
<EditText
android:id="@+id/num"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/btnCalculate"
android:layout_alignLeft="@+id/btnCalculate"
android:layout_marginBottom="20dp"
android:ems="5"
android:inputType="numberDecimal|numberSigned" />
<Button
android:id="@+id/btnCalculate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="Calculate" />
</RelativeLayout>
这是我的Activity类：
package com.danielkim.danielkimcalculator;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.*;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button calc = (Button)findViewById(R.id.btnCalculate);
calc.setOnClickListener(new View.OnClickListener() {
public void onClick(View v)
{
EditText number = (EditText)findViewById(R.id.num);
TextView display = (TextView)findViewById(R.id.display);
double num = Double.parseDouble(number.getText().toString());
num = Double.parseDouble(samplecalc.multNum(num));
display.setText(num + "");
}
});
}
@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;
}
}
这是我samplecalc类做了计算：
package com.danielkim.danielkimcalculator;
public class samplecalc {
private double Num = 0;
public samplecalc(double number) {
Num = number;
}
public static String multNum(double x) {
String re = "";
double num = x * 5;
re = num + "";
return re;
}
public double multNum2() {
double re = Num * 5;
return re;
}
}
的logcat的说：
01-24 18:56:59.760: I/Adreno200-EGLSUB(12532): <ConfigWindowMatch:2081>: Format RGBA_8888.
01-24 18:57:29.640: W/dalvikvm(12532): threadid=1: thread exiting with uncaught exception (group=0x40acc1f8)
01-24 18:57:29.650: E/AndroidRuntime(12532): FATAL EXCEPTION: main
01-24 18:57:29.650: E/AndroidRuntime(12532): java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText
01-24 18:57:29.650: E/AndroidRuntime(12532): at com.danielkim.danielkimcalculator.MainActivity$1.onClick(MainActivity.java:23)
01-24 18:57:29.650: E/AndroidRuntime(12532): at android.view.View.performClick(View.java:3511)
01-24 18:57:29.650: E/AndroidRuntime(12532): at android.view.View$PerformClick.run(View.java:14105)
01-24 18:57:29.650: E/AndroidRuntime(12532): at android.os.Handler.handleCallback(Handler.java:605)
01-24 18:57:29.650: E/AndroidRuntime(12532): at android.os.Handler.dispatchMessage(Handler.java:92)
01-24 18:57:29.650: E/AndroidRuntime(12532): at android.os.Looper.loop(Looper.java:137)
01-24 18:57:29.650: E/AndroidRuntime(12532): at android.app.ActivityThread.main(ActivityThread.java:4429)
01-24 18:57:29.650: E/AndroidRuntime(12532): at java.lang.reflect.Method.invokeNative(Native Method)
01-24 18:57:29.650: E/AndroidRuntime(12532): at java.lang.reflect.Method.invoke(Method.java:511)
01-24 18:57:29.650: E/AndroidRuntime(12532): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
01-24 18:57:29.650: E/AndroidRuntime(12532): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
01-24 18:57:29.650: E/AndroidRuntime(12532): at dalvik.system.NativeStart.main(Native Method)
尝试清洗和重新执行？ – PopoFibo
嘿，这是我做了视频。尝试再次运行它。输入'5'并进行计算。 LogCat之后是否一样？ –
在clicklistners或其他事件侦听器中定义对象并不是一件好事，但这可能不是问题，但您最好纠正它以更好地使用您的代码。 – user2469133