Android 更改活动时应用程序崩溃
由于我有编程经验，我自愿帮助一个社区开发Android应用程序。此应用程序的一部分是需要从一个活动更改为另一个活动。当我尝试运行代码执行此操作时，程序崩溃，LogCat中出现以下异常：Android 更改活动时应用程序崩溃,android,Android,由于我有编程经验，我自愿帮助一个社区开发Android应用程序。此应用程序的一部分是需要从一个活动更改为另一个活动。当我尝试运行代码执行此操作时，程序崩溃，LogCat中出现以下异常： 03-16 20:25:29.164: ERROR/AndroidRuntime(497): FATAL EXCEPTION: main 03-16 20:25:29.164: ERROR/AndroidRuntime(497): java.lang.RuntimeException: Unable t
03-16 20:25:29.164: ERROR/AndroidRuntime(497): FATAL EXCEPTION: main
03-16 20:25:29.164: ERROR/AndroidRuntime(497): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.a.android.app/com.a.android.app.Card}: java.lang.InstantiationException: com.a.android.app.Card
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.ActivityThread.performLaunchActivity(A ctivityThread.java:2585)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.ActivityThread.handleLaunchActivity(Ac tivityThread.java:2679)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.ActivityThread.access$2300(ActivityThr ead.java:125)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.ActivityThread$H.handleMessage(Activit yThread.java:2033)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.os.Handler.dispatchMessage(Handler.java:99 )
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.os.Looper.loop(Looper.java:123)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.ActivityThread.main(ActivityThread.jav a:4627)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at java.lang.reflect.Method.invokeNative(Native Method)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at java.lang.reflect.Method.invoke(Method.java:521)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at com.android.internal.os.ZygoteInit$MethodAndArgsCa ller.run(ZygoteInit.java:868)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at com.android.internal.os.ZygoteInit.main(ZygoteInit .java:626)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at dalvik.system.NativeStart.main(Native Method)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): Caused by: java.lang.InstantiationException: com.a.android.app.Card
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at java.lang.Class.newInstanceImpl(Native Method)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at java.lang.Class.newInstance(Class.java:1429)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.Instrumentation.newActivity(Instrument ation.java:1021)
03-16 20:25:29.164: ERROR/AndroidRuntime(497): at android.app.ActivityThread.performLaunchActivity(A ctivityThread.java:2577)
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".Main"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:icon="@drawable/icon" android:name="Card" android:label="@string/app_name"></activity>
</application>
public class Card extends Activity
{
private int m_Id;
private EditText m_SearchText;
public Card(Bundle savedInstanceState)
{
try
{
super.onCreate(savedInstanceState);
setContentView(R.layout.card);
Bundle extras = getIntent().getExtras();
if(extras == null)
{
// nothing to do here
return;
}
m_Id = extras.getInt("id");
m_SearchText = (EditText)findViewById(R.id.txtSearch2);
m_SearchText.setText(extras.getString("searchText"));
Button search = (Button)findViewById(R.id.btnSearch2);
search.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ReturnToMain(m_SearchText.getText());
}
});
m_SearchText.addTextChangedListener(new TextWatcher(){
public void afterTextChanged(Editable s) { }
public void beforeTextChanged(CharSequence s, int start, int count, int after)
{
ReturnToMain(s);
}
public void onTextChanged(CharSequence s, int start, int before, int count) {}
});
new LongOperation().execute(this);
}
catch(Exception ex)
{
ShowError(ex.getMessage() + "\n" + ex.toString(), "Create Card");
ex.printStackTrace();
}
}
private void ReturnToMain(CharSequence s)
{
Intent i = new Intent();
i.putExtra("searchText", s);
setResult(RESULT_OK, i);
}
private void ShowError(String message, String title)
{
new AlertDialog.Builder(this)
.setTitle("Error! - " + title)
.setMessage(message)
.setNeutralButton("Ok",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) { }
})
.show();
}
private class LongOperation extends AsyncTask<Context, Void, String> {
String cardNumber;
String sortName;
String cardName;
String cardType;
String tr3CardType;
String attribute;
String level;
String icon;
String atk;
String def;
String cardText;
String cardRulings;
Context currentContext;
@Override
protected String doInBackground(Context... params) {
try {
currentContext = params[0];
// search the database for everything with given id
DataBaseHelper myHelper = new DataBaseHelper(currentContext);
try
{
myHelper.createDataBase();
}
catch(IOException ioe)
{
ShowError(ioe.getMessage(), "CDB");
}
try
{
myHelper.openDataBase();
}
catch(SQLException sqle)
{
ShowError(sqle.getMessage(), "ODB");
}
Cursor results = myHelper.ExecSql("SELECT [CardNumber], [SortName], [CardName], [CardType], [Tr3CardType], [Attribute], [Level], [Icon], [ATK], [DEF], [CardText], [CardRulings] FROM Card WHERE _id = " + String.valueOf(m_Id), null);
results.moveToPosition(0);
cardNumber = results.getString(1);
sortName = results.getString(2);
cardName = results.getString(3);
cardType = results.getString(4);
tr3CardType = results.getString(5);
attribute = results.getString(6);
level = results.getString(7);
icon = results.getString(8);
atk = results.getString(9);
def = results.getString(10);
cardText = results.getString(11);
cardRulings = results.getString(12);
results.close();
results = myHelper.ExecSql("SELECT [CardName], [CardRulings] FROM Card WHERE CardRulings LIKE '%" + cardName + "%'", null);
results.moveToFirst();
while(!results.isAfterLast())
{
String[] individualRulings = results.getString(2).split("<br>");
for (int i = 0; i < individualRulings.length; i++)
{
if (individualRulings[i].contains(cardName))
{
cardRulings += "\n\n[" + results.getString(1) + "]: " + individualRulings[i];
}
}
results.moveToNext();
}
results.close();
myHelper.close();
} catch (Exception e) {
ShowError(e.toString() + "\n" + e.getMessage(), "Thread");
}
return "";
}
/* (non-Javadoc)
* @see android.os.AsyncTask#onPostExecute(java.lang.Object)
*/
@Override
protected void onPostExecute(String result) {
try {
// execution of result of Long time consuming operation
((TextView)findViewById(R.id.lblSortName)).setText(sortName);
((TextView)findViewById(R.id.lblCardName)).setText(cardName);
((TextView)findViewById(R.id.lblCardText)).setText(cardText);
((TextView)findViewById(R.id.lblCardNum)).setText("(" + cardNumber + ")");
((TextView)findViewById(R.id.lblCardRulings)).setText(cardRulings);
if(tr3CardType == "Monster")
{
((TextView)findViewById(R.id.lblCardLevelAttr)).setText(", " + level + ", " + attribute);
((TextView)findViewById(R.id.lblCardType)).setText(cardType + ", " + atk + "/" + def);
}
else
{
((TextView)findViewById(R.id.lblCardLevelAttr)).setText("");
if (icon != "")
{
((TextView)findViewById(R.id.lblCardType)).setText(cardType + " (" + icon + ")");
}
else
{
((TextView)findViewById(R.id.lblCardType)).setText(cardType);
}
}
} catch (Exception e) {
ShowError(e.getMessage() + "\n" + e.toString(), "After Thread");
e.printStackTrace();
}
}
/* (non-Javadoc)
* @see android.os.AsyncTask#onPreExecute()
*/
@Override
protected void onPreExecute() {
// Things to be done before execution of long running operation. For example showing ProgessDialog
}
/* (non-Javadoc)
* @see android.os.AsyncTask#onProgressUpdate(Progress[])
*/
@Override
protected void onProgressUpdate(Void... values) {
// Things to be done while execution of long running operation is in progress. For example updating ProgessDialog
}
}
}
公共类卡扩展活动
{
私人国际货币单位Id；
私人编辑文本m_SearchText；
公共卡（捆绑存储状态）
{
尝试
{
super.onCreate（savedInstanceState）；
setContentView（R.layout.card）；
Bundle extras=getIntent（）.getExtras（）；
如果（附加==null）
{
//这里没什么可做的
返回；
}
m_Id=extras.getInt（“Id”）；
m_SearchText=（EditText）findViewById（R.id.txtSearch2）；
m_SearchText.setText（extras.getString（“SearchText”）；
按钮搜索=（按钮）findViewById（R.id.btnSearch2）；
search.setOnClickListener（新视图.OnClickListener（）{
公共void onClick（视图v）{
ReturnToMain（m_SearchText.getText（））；
}
});
m_SearchText.addTextChangedListener（新的TextWatcher（）{
公共无效后文本更改（可编辑的s）{}
更改前文本之前的公共void（字符序列s、int start、int count、int after）
{
海洛托明(s);；
}
public void onTextChanged（字符序列，int start，int before，int count）{}
});
new LongOperation（）。执行（此）；
}
捕获（例外情况除外）
{
淋浴错误（例如getMessage（）+“\n”+例如toString（），“创建卡”）；
例如printStackTrace（）；
}
}
私有void ReturnToMain（字符序列）
{
意图i=新意图（）；
i、 putExtra（“搜索文本”，s）；
setResult（结果_OK，i）；
}
私有无效错误（字符串消息、字符串标题）
{
新建AlertDialog.Builder（此）
.setTitle（“错误！-”+标题）
.setMessage（消息）
.setNeutralButton（“确定”，
新建DialogInterface.OnClickListener（）{
public void onClick（DialogInterface dialog，int which）{}
})
.show（）；
}
私有类LongOperation扩展了异步任务{
字符串卡号；
字符串sortName；
字符串cardName；
字符串卡片类型；
字符串tr3CardType；
字符串属性；
字符串级；
字符串图标；
字符串atk；
字符串定义；
字符串文本；
串连裁决；
语境；
@凌驾
受保护字符串doInBackground（上下文…参数）{
试一试{
currentContext=params[0]；
//在数据库中搜索具有给定id的所有内容
DataBaseHelper myHelper=新的DataBaseHelper（currentContext）；
尝试
{
myHelper.createDataBase（）；
}
捕获（ioe异常ioe）
{
淋浴ROR（ioe.getMessage（），“CDB”）；
}
尝试
{
myHelper.openDataBase（）；
}
捕获（SQLException sqle）
{
淋浴错误（sqle.getMessage（），“ODB”）；
}
游标结果=myHelper.ExecSql（“从卡片中选择[CardNumber]、[SortName]、[CardName]、[CardType]、[Tr3CardType]、[Attribute]、[Level]、[Icon]、[ATK]、[DEF]、[CardText]、[CardRulings]，其中(u id=“+String.valueOf（m_id）），null）；
结果：运动定位（0）；
cardNumber=results.getString（1）；
sortName=results.getString（2）；
cardName=results.getString（3）；
cardType=results.getString（4）；
tr3CardType=results.getString（5）；
attribute=results.getString（6）；
级别=结果。getString（7）；
icon=results.getString（8）；
atk=results.getString（9）；
def=results.getString（10）；
cardText=results.getString（11）；
cardRulings=results.getString（12）；
结果：关闭（）；
结果=myHelper.ExecSql（“从卡片中选择[CardName]，[CardRulings]，其中CardRulings类似“%”“+CardName+“%”，null）；
结果：moveToFirst（）；
而（！results.isAfterLast（））
{
String[]individualRulings=results.getString（2）.split（“
”）；
for（int i=0；ipublic class Card extends Activity
{
private int m_Id;
private EditText m_SearchText;
public Card(Bundle savedInstanceState)
{
try
{
super.onCreate(savedInstanceState);
setContentView(R.layout.card);
Bundle extras = getIntent().getExtras();
if(extras == null)
{
// nothing to do here
return;
}
m_Id = extras.getInt("id");
m_SearchText = (EditText)findViewById(R.id.txtSearch2);
m_SearchText.setText(extras.getString("searchText"));
Button search = (Button)findViewById(R.id.btnSearch2);
search.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ReturnToMain(m_SearchText.getText());
}
});
m_SearchText.addTextChangedListener(new TextWatcher(){
public void afterTextChanged(Editable s) { }
public void beforeTextChanged(CharSequence s, int start, int count, int after)
{
ReturnToMain(s);
}
public void onTextChanged(CharSequence s, int start, int before, int count) {}
});
new LongOperation().execute(this);
}
catch(Exception ex)
{
ShowError(ex.getMessage() + "\n" + ex.toString(), "Create Card");
ex.printStackTrace();
}
}
private void ReturnToMain(CharSequence s)
{
Intent i = new Intent();
i.putExtra("searchText", s);
setResult(RESULT_OK, i);
}
private void ShowError(String message, String title)
{
new AlertDialog.Builder(this)
.setTitle("Error! - " + title)
.setMessage(message)
.setNeutralButton("Ok",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) { }
})
.show();
}
private class LongOperation extends AsyncTask<Context, Void, String> {
String cardNumber;
String sortName;
String cardName;
String cardType;
String tr3CardType;
String attribute;
String level;
String icon;
String atk;
String def;
String cardText;
String cardRulings;
Context currentContext;
@Override
protected String doInBackground(Context... params) {
try {
currentContext = params[0];
// search the database for everything with given id
DataBaseHelper myHelper = new DataBaseHelper(currentContext);
try
{
myHelper.createDataBase();
}
catch(IOException ioe)
{
ShowError(ioe.getMessage(), "CDB");
}
try
{
myHelper.openDataBase();
}
catch(SQLException sqle)
{
ShowError(sqle.getMessage(), "ODB");
}
Cursor results = myHelper.ExecSql("SELECT [CardNumber], [SortName], [CardName], [CardType], [Tr3CardType], [Attribute], [Level], [Icon], [ATK], [DEF], [CardText], [CardRulings] FROM Card WHERE _id = " + String.valueOf(m_Id), null);
results.moveToPosition(0);
cardNumber = results.getString(1);
sortName = results.getString(2);
cardName = results.getString(3);
cardType = results.getString(4);
tr3CardType = results.getString(5);
attribute = results.getString(6);
level = results.getString(7);
icon = results.getString(8);
atk = results.getString(9);
def = results.getString(10);
cardText = results.getString(11);
cardRulings = results.getString(12);
results.close();
results = myHelper.ExecSql("SELECT [CardName], [CardRulings] FROM Card WHERE CardRulings LIKE '%" + cardName + "%'", null);
results.moveToFirst();
while(!results.isAfterLast())
{
String[] individualRulings = results.getString(2).split("<br>");
for (int i = 0; i < individualRulings.length; i++)
{
if (individualRulings[i].contains(cardName))
{
cardRulings += "\n\n[" + results.getString(1) + "]: " + individualRulings[i];
}
}
results.moveToNext();
}
results.close();
myHelper.close();
} catch (Exception e) {
ShowError(e.toString() + "\n" + e.getMessage(), "Thread");
}
return "";
}
/* (non-Javadoc)
* @see android.os.AsyncTask#onPostExecute(java.lang.Object)
*/
@Override
protected void onPostExecute(String result) {
try {
// execution of result of Long time consuming operation
((TextView)findViewById(R.id.lblSortName)).setText(sortName);
((TextView)findViewById(R.id.lblCardName)).setText(cardName);
((TextView)findViewById(R.id.lblCardText)).setText(cardText);
((TextView)findViewById(R.id.lblCardNum)).setText("(" + cardNumber + ")");
((TextView)findViewById(R.id.lblCardRulings)).setText(cardRulings);
if(tr3CardType == "Monster")
{
((TextView)findViewById(R.id.lblCardLevelAttr)).setText(", " + level + ", " + attribute);
((TextView)findViewById(R.id.lblCardType)).setText(cardType + ", " + atk + "/" + def);
}
else
{
((TextView)findViewById(R.id.lblCardLevelAttr)).setText("");
if (icon != "")
{
((TextView)findViewById(R.id.lblCardType)).setText(cardType + " (" + icon + ")");
}
else
{
((TextView)findViewById(R.id.lblCardType)).setText(cardType);
}
}
} catch (Exception e) {
ShowError(e.getMessage() + "\n" + e.toString(), "After Thread");
e.printStackTrace();
}
}
/* (non-Javadoc)
* @see android.os.AsyncTask#onPreExecute()
*/
@Override
protected void onPreExecute() {
// Things to be done before execution of long running operation. For example showing ProgessDialog
}
/* (non-Javadoc)
* @see android.os.AsyncTask#onProgressUpdate(Progress[])
*/
@Override
protected void onProgressUpdate(Void... values) {
// Things to be done while execution of long running operation is in progress. For example updating ProgessDialog
}
}
}
Intent i = new Intent(Main.this, Card.class);
android:name
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.card);
....
}