Android layout 我已经用android写了这段代码，我得到了一个错误

读取异常中的堆栈跟踪：

package com.android.sudhakar.sqlite.database.project;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity
{

    Button insButton;
    Button delButton;
    Button srchButton;
    Button updateButton;


    private DBHelper dbHelper;
    private EditText firstEditText;
    private EditText lastEditText;
    private EditText branchEditText;
    private EditText rollEditText;
    private EditText sscEditText;
    private EditText hscEditText;


    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {

        super.onCreate(savedInstanceState);

        int rollNo = Integer.parseInt(rollEditText.toString()); 
        String fName = firstEditText.toString();
        String lName = lastEditText.toString();
        String branch = branchEditText.toString();
        float ssc = Float.parseFloat(sscEditText.toString());
        float hsc = Float.parseFloat(hscEditText.toString());

        final Object[] object  = {rollNo,fName,lName,branch,ssc,hsc};

        setContentView(R.layout.page);

        try 
        {
            String sql = "insert into studsinfo";
            dbHelper = new DBHelper(this);

            dbHelper.execSql(sql, object);

            AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
            alertBuilder.setTitle("Student Information..");
            final AlertDialog alert = alertBuilder.create();
            alert.show();

            insButton.setOnClickListener(new OnClickListener()
            {

                @Override
                public void onClick(View v)
                {
                    Intent intent = new Intent(MainActivity.this, DeleteActivity.class);
                    intent.putExtra("id", object.toString());
                    startActivity(intent);
                }
            });
        }

        catch (Exception e) 
        {
            e.printStackTrace();
        }

        dbHelper.close();
    }
}

在第37行，您试图访问一个字段或调用一个空对象变量的方法。看起来您正在使用许多未初始化的字段执行此操作

package com.android.sudhakar.sqlite.database.project;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity
{

    Button insButton;
    Button delButton;
    Button srchButton;
    Button updateButton;


    private DBHelper dbHelper;
    private EditText firstEditText;
    private EditText lastEditText;
    private EditText branchEditText;
    private EditText rollEditText;
    private EditText sscEditText;
    private EditText hscEditText;


    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {

        super.onCreate(savedInstanceState);

        int rollNo = Integer.parseInt(rollEditText.toString()); 
        String fName = firstEditText.toString();
        String lName = lastEditText.toString();
        String branch = branchEditText.toString();
        float ssc = Float.parseFloat(sscEditText.toString());
        float hsc = Float.parseFloat(hscEditText.toString());

        final Object[] object  = {rollNo,fName,lName,branch,ssc,hsc};

        setContentView(R.layout.page);

        try 
        {
            String sql = "insert into studsinfo";
            dbHelper = new DBHelper(this);

            dbHelper.execSql(sql, object);

            AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
            alertBuilder.setTitle("Student Information..");
            final AlertDialog alert = alertBuilder.create();
            alert.show();

            insButton.setOnClickListener(new OnClickListener()
            {

                @Override
                public void onClick(View v)
                {
                    Intent intent = new Intent(MainActivity.this, DeleteActivity.class);
                    intent.putExtra("id", object.toString());
                    startActivity(intent);
                }
            });
        }

        catch (Exception e) 
        {
            e.printStackTrace();
        }

        dbHelper.close();
    }
}

06-10 14:57:26.289: ERROR/AndroidRuntime(608): Caused by: java.lang.NullPointerException
06-10 14:57:26.289: ERROR/AndroidRuntime(608):     at com.android.sudhakar.sqlite.database.project.MainActivity.onCreate(MainActivity.java:37)