问题描述
我正在尝试从EditText
中获取输入值,并且要将其保存到sqlite数据库.我不知道如何使用logcat [也请解释如何从LogCat中读取错误].
I am trying to take the input values from EditText
and I want to save it to sqlite Database. I dont know how to use the logcat [also please explain how can I read the errors from the LogCat].
MainActivity.java:
package com.example.database;
import android.support.v7.app.ActionBarActivity;
import android.text.Editable;
import android.app.Activity;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity{
EditText first,last,age,classc;
Button add,view;
String FirstName;
String LastName,Class;
Integer Age;
sqLit myDB;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myDB = new sqLit(this);
Link();
xmlToVar();
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Integer flag=myDB.insertValue(FirstName, LastName, Class, Age);
if (flag==1)
{
Context context=getApplicationContext();
Toast toast = Toast.makeText(context, "Record Added" , Toast.LENGTH_LONG);
toast.show();
}
else
{
Context context=getApplicationContext();
Toast toast = Toast.makeText(context, "Error Occured" , Toast.LENGTH_LONG);
toast.show();
}
}
});
}
public void Link()
{
first=(EditText) findViewById(R.id.editFirst);
last=(EditText) findViewById(R.id.editLast);
classc=(EditText) findViewById(R.id.editClass);
age=(EditText) findViewById(R.id.editAge);
add=(Button) findViewById(R.id.Add);
view=(Button) findViewById(R.id.ViewAll);
}
public void xmlToVar()
{
FirstName = first.getText().toString();
LastName = last.getText().toString();
Class = classc.getText().toString();
Age = Integer.parseInt(age.getText().toString());
}
}
sqLit.java:
package com.example.database;
import org.w3c.dom.Text;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
public class sqLit extends SQLiteOpenHelper
{
public static final String DB_NAME="student12.db";
public static final String TABLE_NAME="class1";
public static final String COL_1="ROLL NO";
public static final String COL_2="First Name";
public static final String COL_3="Last Name";
public static final String COL_4="Class";
public static final String COL_5="Age";
public sqLit(Context context) {
super(context, DB_NAME, null, 1);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("Create table " + TABLE_NAME + "(" + COL_1 + "INTEGER AUTOINCREMENT PRIMARY KEY," + COL_2 + "TEXT," + COL_3 + "TEXT," + COL_4 + "TEXT," + COL_5 + "INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("Drop Table If Exist" + TABLE_NAME );
onCreate(db);
}
public Integer insertValue(String FirstName, String LastName, String Class, Integer Age)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentV = new ContentValues();
contentV.put(COL_2, FirstName);
contentV.put(COL_3, LastName);
contentV.put(COL_4, Class);
contentV.put(COL_5, Age);
long isInserted = db.insert(TABLE_NAME, null, contentV);
if (isInserted == -1){
return 0;
}
else
{
return 1;
}
}
}
另外,请解释如何使用LogCat,因为我不懂如何阅读.
Also, please explain how to use LogCat as I don't understand how to read it.
LOGCAT:
06-11 18:44:39.650: E/Trace(29536): error opening trace file: No such file or directory (2)
06-11 18:44:39.660: D/AndroidRuntime(29536): Shutting down VM
06-11 18:44:39.660: W/dalvikvm(29536): threadid=1: thread exiting with uncaught exception (group=0xb3f2b288)
06-11 18:44:39.660: E/AndroidRuntime(29536): FATAL EXCEPTION: main
06-11 18:44:39.660: E/AndroidRuntime(29536): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.database/com.example.database.MainActivity}: java.lang.NumberFormatException: Invalid int: ""
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.os.Handler.dispatchMessage(Handler.java:99)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.os.Looper.loop(Looper.java:137)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.ActivityThread.main(ActivityThread.java:4745)
06-11 18:44:39.660: E/AndroidRuntime(29536): at java.lang.reflect.Method.invokeNative(Native Method)
06-11 18:44:39.660: E/AndroidRuntime(29536): at java.lang.reflect.Method.invoke(Method.java:511)
06-11 18:44:39.660: E/AndroidRuntime(29536): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-11 18:44:39.660: E/AndroidRuntime(29536): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-11 18:44:39.660: E/AndroidRuntime(29536): at dalvik.system.NativeStart.main(Native Method)
06-11 18:44:39.660: E/AndroidRuntime(29536): Caused by: java.lang.NumberFormatException: Invalid int: ""
06-11 18:44:39.660: E/AndroidRuntime(29536): at java.lang.Integer.invalidInt(Integer.java:138)
06-11 18:44:39.660: E/AndroidRuntime(29536): at java.lang.Integer.parseInt(Integer.java:359)
06-11 18:44:39.660: E/AndroidRuntime(29536): at java.lang.Integer.parseInt(Integer.java:332)
06-11 18:44:39.660: E/AndroidRuntime(29536): at com.example.database.MainActivity.xmlToVar(MainActivity.java:72)
06-11 18:44:39.660: E/AndroidRuntime(29536): at com.example.database.MainActivity.onCreate(MainActivity.java:34)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.Activity.performCreate(Activity.java:5008)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
06-11 18:44:39.660: E/AndroidRuntime(29536): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
06-11 18:44:39.660: E/AndroidRuntime(29536): ... 11 more
06-11 18:46:03.652: D/dalvikvm(30256): Not late-enabling CheckJNI (already on)
06-11 18:46:03.682: E/Trace(30256): error opening trace file: No such file or directory (2)
06-11 18:46:03.712: D/AndroidRuntime(30256): Shutting down VM
06-11 18:46:03.712: W/dalvikvm(30256): threadid=1: thread exiting with uncaught exception (group=0xb3f2b288)
06-11 18:46:03.712: E/AndroidRuntime(30256): FATAL EXCEPTION: main
06-11 18:46:03.712: E/AndroidRuntime(30256): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.database/com.example.database.MainActivity}: java.lang.NumberFormatException: Invalid int: ""
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.os.Handler.dispatchMessage(Handler.java:99)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.os.Looper.loop(Looper.java:137)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.ActivityThread.main(ActivityThread.java:4745)
06-11 18:46:03.712: E/AndroidRuntime(30256): at java.lang.reflect.Method.invokeNative(Native Method)
06-11 18:46:03.712: E/AndroidRuntime(30256): at java.lang.reflect.Method.invoke(Method.java:511)
06-11 18:46:03.712: E/AndroidRuntime(30256): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-11 18:46:03.712: E/AndroidRuntime(30256): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-11 18:46:03.712: E/AndroidRuntime(30256): at dalvik.system.NativeStart.main(Native Method)
06-11 18:46:03.712: E/AndroidRuntime(30256): Caused by: java.lang.NumberFormatException: Invalid int: ""
06-11 18:46:03.712: E/AndroidRuntime(30256): at java.lang.Integer.invalidInt(Integer.java:138)
06-11 18:46:03.712: E/AndroidRuntime(30256): at java.lang.Integer.parseInt(Integer.java:359)
06-11 18:46:03.712: E/AndroidRuntime(30256): at java.lang.Integer.parseInt(Integer.java:332)
06-11 18:46:03.712: E/AndroidRuntime(30256): at com.example.database.MainActivity.xmlToVar(MainActivity.java:73)
06-11 18:46:03.712: E/AndroidRuntime(30256): at com.example.database.MainActivity.onCreate(MainActivity.java:35)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.Activity.performCreate(Activity.java:5008)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
06-11 18:46:03.712: E/AndroidRuntime(30256): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
06-11 18:46:03.712: E/AndroidRuntime(30256): ... 11 more
06-11 18:53:33.378: E/Trace(2383): error opening trace file: No such file or directory (2)
06-11 18:53:33.408: D/AndroidRuntime(2383): Shutting down VM
06-11 18:53:33.408: W/dalvikvm(2383): threadid=1: thread exiting with uncaught exception (group=0xb3f2b288)
06-11 18:53:33.408: E/AndroidRuntime(2383): FATAL EXCEPTION: main
06-11 18:53:33.408: E/AndroidRuntime(2383): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.database/com.example.database.MainActivity}: java.lang.NumberFormatException: Invalid int: ""
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.os.Handler.dispatchMessage(Handler.java:99)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.os.Looper.loop(Looper.java:137)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.ActivityThread.main(ActivityThread.java:4745)
06-11 18:53:33.408: E/AndroidRuntime(2383): at java.lang.reflect.Method.invokeNative(Native Method)
06-11 18:53:33.408: E/AndroidRuntime(2383): at java.lang.reflect.Method.invoke(Method.java:511)
06-11 18:53:33.408: E/AndroidRuntime(2383): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-11 18:53:33.408: E/AndroidRuntime(2383): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-11 18:53:33.408: E/AndroidRuntime(2383): at dalvik.system.NativeStart.main(Native Method)
06-11 18:53:33.408: E/AndroidRuntime(2383): Caused by: java.lang.NumberFormatException: Invalid int: ""
06-11 18:53:33.408: E/AndroidRuntime(2383): at java.lang.Integer.invalidInt(Integer.java:138)
06-11 18:53:33.408: E/AndroidRuntime(2383): at java.lang.Integer.parseInt(Integer.java:359)
06-11 18:53:33.408: E/AndroidRuntime(2383): at java.lang.Integer.parseInt(Integer.java:332)
06-11 18:53:33.408: E/AndroidRuntime(2383): at com.example.database.MainActivity.xmlToVar(MainActivity.java:73)
06-11 18:53:33.408: E/AndroidRuntime(2383): at com.example.database.MainActivity.onCreate(MainActivity.java:35)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.Activity.performCreate(Activity.java:5008)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
06-11 18:53:33.408: E/AndroidRuntime(2383): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
06-11 18:53:33.408: E/AndroidRuntime(2383): ... 11 more
推荐答案
Caused by: java.lang.NumberFormatException: Invalid int: ""
(在FATAL EXCEPTION:
之后)告诉我们您正在尝试解析int
,但是您尝试解析的值是空的String
.
(after FATAL EXCEPTION:
) tells us you are trying to parse an int
but the value you are trying to parse is an empty String
.
此行(第一个引用您的课程的行)告诉我们它是哪一行
this line (the first that references your class) tells us which line it was
at com.example.database.MainActivity.xmlToVar(MainActivity.java:72)
之所以发生这种情况,是因为您在EditText
输入任何值之前在onCreate()
中调用它.
this is happening because you are calling it in onCreate()
before the EditText
has any value entered.
从上面的行中,我们可以看到错误发生在方法xmlToVar
的MainActivity
中的第72行,该错误应该是
From the line above, we can see that the error happens in MainActivity
in the method xmlToVar
at line 72 which should be
Age = Integer.parseInt(age.getText().toString());
要解决此问题,您应该在onClick
或某些事件侦听器中调用该方法.您还应该将其包围在try/catch
中,或使用其他一些验证检查.
To solve this, you should call that method in an onClick
or some event listener. You also should surround it in a try/catch
or use some other validation checking.
您应该阅读以下问题及其答案以获取更多详细信息:
You should read the following questions and their answers for more details:
java.lang.NumberFormatException:无效的int:""在android
基本上,请阅读它给您的错误,然后查找提到您的班级的第一行.有时您需要更深入地阅读,但对于通常已经足够的基本错误.
basically, read the error it gives you then look for the first line which mentions your class. Sometimes you need to read deeper but for basic errors that is usually enough.
请注意,堆栈跟踪不是特定于Eclipse的,也不是特定于Java/Android的.您可以使用其他语言/IDE/控制台获得类似的崩溃日志
Note that the stacktrace isn't Eclipse or even Java/Android specific. You can get some sort of crash log like this in other languages/IDEs/Consoles
这篇关于NumberFormatException无效的int“"的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!