我创建了一个从我的应用程序的data / data文件夹复制数据库的函数，但是当我使用函数CopyDatabase（）时，我一直强制关闭。
这是我的代码绑定到按钮
public class StudentsFormScreen extends Activity
{
SQLiteDatabase db;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
getActionBar().hide();
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.studentsform_layout);
db=openOrCreateDatabase("MyDB1",MODE_WORLD_WRITEABLE, null);
db.execSQL("CREATE TABLE IF NOT EXISTS Student(fname VARCHAR,lname VARCHAR,email VARCHAR);");
String path = db.getPath();
TextView path1 = (TextView) findViewById(R.id.pather);
path1.setText(path);
}
public void CopyDatabase()
{
try
{
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite())
{
String currentDBPath = "/data/test.com.classmanagertest/databases/MyDB1.db";
String backupDBPath = "MyDB1.db";
File currentDB = new File(data,currentDBPath);
File backupDB = new File(sd, backupDBPath);
if (currentDB.exists())
{
FileChannel src = new FileInputStream(currentDB).getChannel();
FileChannel dst = new FileOutputStream(backupDB).getChannel();
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
Toast.makeText(getApplicationContext(),"Backup Complete", Toast.LENGTH_SHORT).show();
}
}
}
catch (Exception e)
{
e.printStackTrace();
displayExceptionMessage(e.getMessage());
}
}
public void displayExceptionMessage(String msg)
{
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
}
/* public void CopyDatabase()
{
DataBaseHelper myDbHelper = new DataBaseHelper(this);
try
{
myDbHelper.createDataBase();
}
catch (IOException ioe)
{
throw new Error("Unable to create database");
}
try
{
myDbHelper.openDataBase();
}
catch (SQLException e)
{
e.printStackTrace();
}
}
*/
public void CreateScreen(View view)
{
Intent StudentCreateScreenIntent = new Intent(this, StudentsFormCreate.class);
startActivity(StudentCreateScreenIntent);
overridePendingTransition(R.anim.transition,R.anim.right2left);
}
public void UpdateScreen (View view)
{
Intent StudentUpdateScreenIntent = new Intent(this, StudentsFormUpdate.class );
startActivity(StudentUpdateScreenIntent);
overridePendingTransition(R.anim.transition,R.anim.right2left);
}
public void DeleteScreen (View view)
{
Intent StudentDeleteScreenIntent = new Intent (this, StudentsFormDelete.class);
startActivity(StudentDeleteScreenIntent);
overridePendingTransition(R.anim.transition,R.anim.right2left);
}
public void ShowData(View view)
{
Cursor c=db.rawQuery("SELECT * from Student", null);
int count= c.getCount();
c.moveToFirst();
TableLayout tableLayout = new TableLayout(getApplicationContext());
tableLayout.setVerticalScrollBarEnabled(true);
TableRow tableRow;
TextView textView,textView1,textView2,textView3,textView4,textView5;
tableRow = new TableRow(getApplicationContext());
textView=new TextView(getApplicationContext());
textView.setText("Firstname");
textView.setTextColor(Color.RED);
textView.setTypeface(null, Typeface.BOLD);
textView.setPadding(20, 20, 20, 20);
tableRow.addView(textView);
textView4=new TextView(getApplicationContext());
textView4.setText("LastName");
textView4.setTextColor(Color.RED);
textView4.setTypeface(null, Typeface.BOLD);
textView4.setPadding(20, 20, 20, 20);
tableRow.addView(textView4);
textView5=new TextView(getApplicationContext());
textView5.setText("Email");
textView5.setTextColor(Color.RED);
textView5.setTypeface(null, Typeface.BOLD);
textView5.setPadding(20, 20, 20, 20);
tableRow.addView(textView5);
tableLayout.addView(tableRow);
for (Integer j = 0; j < count; j++)
{
tableRow = new TableRow(getApplicationContext());
textView1 = new TextView(getApplicationContext());
textView1.setText(c.getString(c.getColumnIndex("fname")));
textView2 = new TextView(getApplicationContext());
textView2.setText(c.getString(c.getColumnIndex("lname")));
textView3 = new TextView(getApplicationContext());
textView3.setText(c.getString(c.getColumnIndex("email")));
textView1.setPadding(20, 20, 20, 20);
textView2.setPadding(20, 20, 20, 20);
textView3.setPadding(20, 20, 20, 20);
tableRow.addView(textView1);
tableRow.addView(textView2);
tableRow.addView(textView3);
tableLayout.addView(tableRow);
c.moveToNext() ;
}
setContentView(tableLayout);
db.close();
}
}
这是我得到的错误：
01-23 20:53:07.539 32699-32699/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: test.com.classmanagertest, PID: 32699
java.lang.IllegalStateException: Could not find a method CopyDatabase(View) in the activity class test.com.classmanagertest.StudentsFormScreen for onClick handler on view class android.widget.Button with id 'CopyDatabase'
at android.view.View$1.onClick(View.java:3994)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
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.NoSuchMethodException: CopyDatabase [class android.view.View]
at java.lang.Class.getMethod(Class.java:664)
at java.lang.Class.getMethod(Class.java:643)
at android.view.View$1.onClick(View.java:3987)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
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)
我获得了许可：
<uses-permission
android:name = "android.permission.WRITE_EXTERNAL_STORAGE"/>
非常感谢任何帮助！
答案 0 :(得分：0)
我认为您已在XML Layout中的某个按钮的onClick中添加了方法调用。在这种情况下，您正在调用的方法应该有一个View v参数。
因此，您的方法定义应如下所示：public void CopyDatabase(View v)
当你点击按钮时，android会查找名为CopyDatabase(View v)的方法，但无法在活动中找到它，因此会抛出NoSuchMethodException