这是logcat。我的程序是计算器，我不知道如何解决这个错误
E/AndroidRuntime(620): java.lang.RuntimeException: Unable to start activity ComponentInfo{calculator.tt/calculator.tt.CalculatorActivity}: java.lang.ClassCastException: android.widget.EditText cannot be cast to android.widget.Button
这是main.xml文件，我的布局有一个edittext和5个tablerow。在最后一个表格中，我使用相同的按钮比另一个按钮更大。
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/answer"
android:layout_width="match_parent"
android:layout_height="70dp"
android:ems="10"
android:gravity="right|center|end"
android:lines="1" >
<requestFocus />
</EditText>
<TableRow
android:id="@+id/TableRow02"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="left"
android:paddingLeft="5dp"
android:paddingTop="30dp" >
<Button
android:id="@+id/open"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="(" />
<Button
android:id="@+id/close"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text=")" />
<ImageButton
android:id="@+id/sqrt"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:src="@drawable/sqrt" />
<Button
android:id="@+id/add"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="+" />
</TableRow>
<TableRow
android:id="@+id/tableRow1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="5dp" >
<ImageButton
android:id="@+id/x2"
android:layout_width="77dp"
android:layout_height="match_parent"
android:src="@drawable/x2" />
<ImageButton
android:id="@+id/x3"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:src="@drawable/x3" />
<Button
android:id="@+id/giaithua"
android:layout_width="77dp"
android:layout_height="match_parent"
android:text="x!" />
<Button
android:id="@+id/sub"
android:layout_width="77dp"
android:layout_height="match_parent"
android:text="-" />
</TableRow>
<TableRow
android:id="@+id/TableRow03"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="5dp" >
<Button
android:id="@+id/key7"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="7" />
<Button
android:id="@+id/key8"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="8" />
<Button
android:id="@+id/key9"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="9" />
<Button
android:id="@+id/mul"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="*" />
</TableRow>
<TableRow
android:id="@+id/TableRow04"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="5dp" >
<Button
android:id="@+id/key4"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="4" />
<Button
android:id="@+id/key5"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="5" />
<Button
android:id="@+id/key6"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="6" />
<Button
android:id="@+id/div"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="/" />
</TableRow>
<TableRow
android:id="@+id/TableRow05"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="5dp" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<Button
android:id="@+id/key1"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="1" />
<Button
android:id="@+id/key2"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="2" />
<Button
android:id="@+id/key3"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="3" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<Button
android:id="@+id/dot"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="." />
<Button
android:id="@+id/key0"
android:layout_width="77dp"
android:layout_height="wrap_content"
android:text="0" />
<ImageButton
android:id="@+id/minus"
android:layout_width="77dp"
android:layout_height="match_parent"
android:src="@drawable/minus" />
</LinearLayout>
</LinearLayout>
<Button
android:id="@+id/Equal"
android:layout_width="77dp"
android:layout_height="95dp"
android:text="=" />
</TableRow>
</LinearLayout>
这是CalculatorActivity：
package calculator.tt;
import android.app.Activity;
import android.os.Bundle;
import android.text.InputType;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
public class CalculatorActivity extends Activity {
EditText answer1;
String as;
char c;
double a, b, e;
boolean k;
Button addbutton;
Button subbutton;
Button divbutton;
Button mulbutton;
ImageButton x2button;
ImageButton x3button;
ImageButton sqrtbutton;
Button gtbutton;
Button opbutton;
Button clbutton;
Button dotbutton;
ImageButton minusbutton;
Button key0button;
Button key1button;
Button key2button;
Button key3button;
Button key4button;
Button key5button;
Button key6button;
Button key7button;
Button key8button;
Button key9button;
Button equalbutton;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/*Khai báo các lớp cho các button*/
answer1 = (EditText)findViewById(R.id.answer);
answer1.setInputType(InputType.TYPE_NULL);
addbutton = (Button)findViewById(R.id.add);
addbutton.setOnClickListener(new AddbuttonHandler());
subbutton = (Button)findViewById(R.id.sub);
subbutton.setOnClickListener(new SubbuttonHandler());
divbutton = (Button)findViewById(R.id.div);
divbutton.setOnClickListener(new DivbuttonHandler());
mulbutton = (Button)findViewById(R.id.mul);
mulbutton.setOnClickListener(new MulbuttonHandler());
equalbutton = (Button)findViewById(R.id.answer);
equalbutton.setOnClickListener(new EqualbuttonHandler());
sqrtbutton = (ImageButton)findViewById(R.id.sqrt);
sqrtbutton.setOnClickListener(new SqrtbuttonHandler());
x2button = (ImageButton)findViewById(R.id.x2);
x2button.setOnClickListener(new X2buttonHandler());
x3button = (ImageButton)findViewById(R.id.x3);
x3button.setOnClickListener(new X3buttonHandler());
minusbutton = (ImageButton)findViewById(R.id.minus);
minusbutton.setOnClickListener(new MinusbuttonHandler());
gtbutton = (Button)findViewById(R.id.giaithua);
gtbutton.setOnClickListener(new GtbuttonHandler());
dotbutton = (Button)findViewById(R.id.dot);
dotbutton.setOnClickListener(new DotbuttonHandler());
key0button = (Button)findViewById(R.id.key0);
key0button.setOnClickListener(new key0buttonHandler());
key1button = (Button)findViewById(R.id.key1);
key1button.setOnClickListener(new key1buttonHandler());
key2button = (Button)findViewById(R.id.key2);
key2button.setOnClickListener(new key2buttonHandler());
key3button = (Button)findViewById(R.id.key3);
key3button.setOnClickListener(new key3buttonHandler());
key4button = (Button)findViewById(R.id.key4);
key4button.setOnClickListener(new key4buttonHandler());
key5button = (Button)findViewById(R.id.key5);
key5button.setOnClickListener(new key5buttonHandler());
key6button = (Button)findViewById(R.id.key6);
key6button.setOnClickListener(new key6buttonHandler());
key7button = (Button)findViewById(R.id.key7);
key7button.setOnClickListener(new key7buttonHandler());
key8button = (Button)findViewById(R.id.key8);
key8button.setOnClickListener(new key8buttonHandler());
key9button = (Button)findViewById(R.id.key9);
key9button.setOnClickListener(new key9buttonHandler());
Log.e("Đang chạy đến đây","Xong khai bao cac lop");
}
/* Các lớp cho button*/
private class X2buttonHandler implements OnClickListener{
public void onClick (View v){
k=true;
a = Double.parseDouble(answer1.getText().toString());
answer1.setText(a*a+"");
}
}
private class X3buttonHandler implements OnClickListener{
public void onClick (View v){
k=true;
a = Double.parseDouble(answer1.getText().toString());
answer1.setText(a*a*a+"");
}
}
private class MinusbuttonHandler implements OnClickListener{
public void onClick (View v){
a = Double.parseDouble(answer1.getText().toString());
answer1.setText(-a+"");
}
}
/*Tính căn bậc 2*/
private class SqrtbuttonHandler implements OnClickListener{
public void onClick (View v){
k=true;
a = Double.parseDouble(answer1.getText().toString());
b = Math.sqrt(a);
answer1.setText(b+"");
}
}
/*Tinh giai thua*/
private class GtbuttonHandler implements OnClickListener{
public void onClick (View v){
k=true;
a = Double.parseDouble(answer1.getText().toString());
b=1;
for (int i=1;i<a+1;i++)
{
b=b*i;
}
answer1.setText(b+"");
}
}
private class DotbuttonHandler implements OnClickListener{
public void onClick (View v){
int i;
as = answer1.getText().toString();
if (k)
answer1.setText("");
k=false;
/*Chi cho duy nhat 1 dau cham xuat hien*/
for (i=0;i<as.length();i++)
if(as.charAt(i)==46)
{ i=1;
break;
}
if (i!=1)
answer1.append(".");
}
}
private class key0buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("0");
k=false;
}
}
private class key1buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("1");
k=false;
}
}
private class key2buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("2");
k=false;
}
}
private class key3buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("3");
k=false;
}
}
private class key4buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("4");
k=false;
}
}
private class key5buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("5");
k=false;
}
}
private class key6buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("6");
k=false;
}
}
private class key7buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("7");
k=false;
}
}
private class key8buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("8");
k=false;
}
}
private class key9buttonHandler implements OnClickListener{
public void onClick (View v){
if (k)
answer1.setText("");
answer1.append("9");
k=false;
}
}
private class AddbuttonHandler implements OnClickListener{
public void onClick (View v){
int i,z=0;
String a1=null,a2=null;
for (i=0;i<as.length();i++)
if (as.charAt(i)==43||as.charAt(i)==42||as.charAt(i)==45||as.charAt(i)==47){
a1 = as.substring(0,i-1);
a2 = as.substring(i+1,as.length());
z=as.charAt(i);
break;
}
a = Double.parseDouble(a1);
b = Double.parseDouble(a2);
if (z==43)
answer1.setText(a+b + "");
if (z==42)
answer1.setText(a*b + "");
if (z==45)
answer1.setText(a-b + "");
else answer1.setText(a/b + "");
answer1.append("+");
}
}
private class MulbuttonHandler implements OnClickListener{
public void onClick (View v){
int i,z=0;
String a1=null,a2=null;
for (i=0;i<as.length();i++)
if (as.charAt(i)==43||as.charAt(i)==42||as.charAt(i)==45||as.charAt(i)==47){
a1 = as.substring(0,i-1);
a2 = as.substring(i+1,as.length());
z=as.charAt(i);
break;
}
a = Double.parseDouble(a1);
b = Double.parseDouble(a2);
if (z==43)
answer1.setText(a+b + "");
if (z==42)
answer1.setText(a*b + "");
if (z==45)
answer1.setText(a-b + "");
else answer1.setText(a/b + "");
answer1.append("*");
}
}
private class SubbuttonHandler implements OnClickListener{
public void onClick (View v){
int i,z=0;
String a1=null,a2=null;
for (i=0;i<as.length();i++)
if (as.charAt(i)==43||as.charAt(i)==42||as.charAt(i)==45||as.charAt(i)==47){
a1 = as.substring(0,i-1);
a2 = as.substring(i+1,as.length());
z=as.charAt(i);
break;
}
a = Double.parseDouble(a1);
b = Double.parseDouble(a2);
if (z==43)
answer1.setText(a+b + "");
if (z==42)
answer1.setText(a*b + "");
if (z==45)
answer1.setText(a-b + "");
else answer1.setText(a/b + "");
answer1.append("-");
}
}
private class DivbuttonHandler implements OnClickListener{
public void onClick (View v){
int i,z=0;
String a1=null,a2=null;
for (i=0;i<as.length();i++)
if (as.charAt(i)==43||as.charAt(i)==42||as.charAt(i)==45||as.charAt(i)==47){
a1 = as.substring(0,i-1);
a2 = as.substring(i+1,as.length());
z=as.charAt(i);
break;
}
a = Double.parseDouble(a1);
b = Double.parseDouble(a2);
if (z==43)
answer1.setText(a+b + "");
if (z==42)
answer1.setText(a*b + "");
if (z==45)
answer1.setText(a-b + "");
else answer1.setText(a/b + "");
answer1.append("/");
}
}
private class EqualbuttonHandler implements OnClickListener{
public void onClick (View v){
int i,z=0;
String a1 = null, a2 = null;
k=true;
as = answer1.getText().toString();
for (i=0;i<as.length();i++)
if (as.charAt(i)==43||as.charAt(i)==42||as.charAt(i)==45||as.charAt(i)==47){
a1 = as.substring(0,i-1);
a2 = as.substring(i+1,as.length());
z=as.charAt(i);
break;
}
a = Double.parseDouble(a1);
b = Double.parseDouble(a2);
if (z==43)
answer1.setText(a+b + "");
if (z==42)
answer1.setText(a*b + "");
if (z==45)
answer1.setText(a-b + "");
else answer1.setText(a/b + "");
}
}
}
答案 0 :(得分：2)
在这条Java专栏中：
equalbutton =（Button）findViewById（R.id.answer）;
您正在查找由此XML定义的EditText：
＆LT;的EditText
机器人：ID = “@ + ID /答案”
看起来你打算这样写：
equalbutton =（Button）findViewById（R.id.Equal）;