[英]Fatal Exception, java lang null pointer exception
我的以下代码未显示任何错误,但未执行。
package my.project.mil;
import android.content.Context;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class Cbdata extends MainActivity {
public String str;
public void onReceive(Context context, Intent intent) {
//---get the CB message passed in---
Bundle bundle = intent.getExtras();
SmsCbMessage[] msgs = null;
str = "";
if (bundle != null) {
//---retrieve the SMS message received---
Object[] pdus = (Object[]) bundle.get("pdus");
msgs = new SmsCbMessage[pdus.length];
for (int i=0; i<msgs.length; i++) {
msgs[i] = SmsCbMessage.createFromPdu((byte[])pdus[i]);
str += "CB " + msgs[i].getGeographicalScope() + msgs[i].getMessageCode() + msgs[i].getMessageIdentifier() + msgs[i].getUpdateNumber();
str += " :";
str += msgs[i].getMessageBody().toString();
str += "\n";
}}
}
SQLiteDatabase cd = openOrCreateDatabase("MLIdb", MODE_WORLD_READABLE, null);
Button submit;
Button viewdb;
EditText name;
@Override
public void onCreate(Bundle savedInstanceState)
{
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.seventh);
viewdb = (Button) findViewById(R.id.viewdb);
submit = (Button) findViewById(R.id.submit);
name = (EditText) findViewById(R.id.name);
submit.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0) {
String locname = name.getText().toString();
if (locname.length()>0)
{
cd.execSQL("CREATE TABLE IF NOT EXITSTS MLITable (CblocationCode INT(10), CblocationName VARCHAR);");
cd.execSQL("INSERT INTO MLITable VALUES (' ',' ');" +str +locname);
Toast.makeText(getBaseContext(), "value successfully entered.", Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(getBaseContext(), "Please enter the location name, for example 'Home'.", Toast.LENGTH_LONG).show();
}
}
});
cd.close();
viewdb.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0) {
// TODO Auto-generated method stub
// here comes the code for viewing the database
}
});
}
}
而且我的错误日志如下所示,我还检查了清单文件和MainActivity文件,但没有遇到任何麻烦。
我的代码应该收集用户的基站塔区代码,并通过用户选择名称将其保存在数据库中,该数据库由两个属性组成,一个属性是从用户处收集的位置名称,其次是基站的广播塔信息。是从onReceive方法获得的,单独使用onReceive方法可以正常工作。
仅当我将数据库集成到代码中时,才会发生此问题。
谢谢。
SQLiteDatabase cd = openOrCreateDatabase("MLIdata", MODE_WORLD_WRITEABLE, null);
尝试将其替换为
SQLiteDatabase cd = openOrCreateDatabase("MLIdata", MODE_WORLD_WRITEABLE);
我在上面的代码中的错误,
最终正确的代码是
public class Cbdata extends MainActivity {
public String str;
public void onReceive(Context context, Intent intent) {
//---get the CB message passed in---
Bundle bundle = intent.getExtras();
SmsCbMessage[] msgs = null;
str = "";
if (bundle != null) {
//---retrieve the SMS message received---
Object[] pdus = (Object[]) bundle.get("pdus");
msgs = new SmsCbMessage[pdus.length];
for (int i=0; i<msgs.length; i++) {
msgs[i] = SmsCbMessage.createFromPdu((byte[])pdus[i]);
str += "CB " + msgs[i].getGeographicalScope() + msgs[i].getMessageCode() + msgs[i].getMessageIdentifier() + msgs[i].getUpdateNumber();
str += " :";
str += msgs[i].getMessageBody().toString();
str += "\n";
}}
}
Button submit;
Button viewdb;
EditText name;
@Override
public void onCreate(Bundle savedInstanceState)
{
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.seventh);
viewdb = (Button) findViewById(R.id.viewdb);
submit = (Button) findViewById(R.id.submit);
name = (EditText) findViewById(R.id.name);
submit.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0) {
String locname = name.getText().toString();
if (locname.length()>0)
{
SQLiteDatabase cd = openOrCreateDatabase("mydata", MODE_WORLD_READABLE, null);
cd.execSQL("CREATE TABLE IF NOT EXISTS MLITable (CblocationCode INT(10), CblocationName VARCHAR);");
cd.execSQL("INSERT INTO MLITable VALUES ('"+str+ "','"+locname+ "');");
Toast.makeText(getBaseContext(), "value successfully entered.", Toast.LENGTH_LONG).show();
cd.close();
}
else
{
Toast.makeText(getBaseContext(), "Please enter the location name, for example 'Home'.", Toast.LENGTH_LONG).show();
}
}
});
viewdb.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0) {
// TODO Auto-generated method stub
// here comes the code for viewing the database
}
});
}
}
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