越来越插入空值 [英] null values getting inserted

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本文介绍了越来越插入空值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我创建一个简单的应用程序添加名和密码数据库。
但是，当我调试亩App中的名称和密码字段都显示为空eventhough我已经在textxbox输入的值

主类

 包com.example.logintp;    进口的java.util.List;    进口android.R.layout;
    进口android.app.Activity;
    进口android.os.Bundle;
    进口android.view.View;
    进口android.view.View.OnClickListener;
    进口android.widget.Button;
    进口android.widget.EditText;
    进口android.widget.TextView;    进口com.example.logintp.R.id;    公共类MainDB延伸活动{
        TextView的名，密码，秀王;
        的EditText etname，etpassword;
        按钮保存，展示;
        串S1，S2;        @覆盖
        保护无效的onCreate（捆绑savedInstanceState）{
            super.onCreate（savedInstanceState）;
            的setContentView（R.layout.activity_main）;
            最后DbClass DB =新DbClass（本）;
            名=（的TextView）findViewById（R.id.name）;
            密码=（的TextView）findViewById（R.id.password）;
            秀王=（的TextView）findViewById（R.id.show）;
            etname =（EditText上）findViewById（R.id.etName）;
            etpassword =（EditText上）findViewById（id.etPassword）;
            节省=（按钮）findViewById（R.id.save）;
            秀=（按钮）findViewById（R.id.Display）;
    save.setOnClickListener（新OnClickListener（）{                @覆盖
                公共无效的onClick（查看为arg0）{
                    // TODO自动生成方法存根
                    。S1 = etname.getText（）的toString（）;
                    。S2 = etpassword.getText（）的toString（）;
                    长的id = db.insertData（新登录（S1，S2））;
                    如果（ID℃，）{
                        CommonFunctions.display（MainDB.this不成功的）;                    }其他{
                        CommonFunctions.display（MainDB.thisSUCESSFUL）;
                    }                }
            }）;
        }
    }

数据库处理器CLASS 

 包com.example.logintp;
进口android.content.ContentValues​​;
进口android.content.Context;
进口android.database.Cursor;
进口android.database.sqlite.SQLiteDatabase;
进口android.database.sqlite.SQLiteOpenHelper;公共类DbClass扩展SQLiteOpenHelper {私有静态最后弦乐DB_NAME =LoginDetails;
私有静态最后弦乐TABLE_NAME =登陆;
私有静态最终字符串名称=名;
私有静态最后的字符串密码=密码;
私有静态最终诠释db_version = 1;
私有静态最后弦乐CREATE_TABLE =CREATE TABLE+ TABLE_NAME
        +（+名称+VARCHAR（200），+密码+VARCHAR（200）
        +）;公共DbClass（上下文的背景下）{
    超（背景下，DB_NAME，空，db_version）;
}公共无效的onCreate（SQLiteDatabase DB）{
    // TODO自动生成方法存根
    db.execSQL（CREATE_TABLE）;}@覆盖
公共无效onUpgrade（SQLiteDatabase为arg0，ARG1 INT，INT ARG2）{
    // TODO自动生成方法存根}众长insertData（登入l）{    SQLiteDatabase分贝= getWritableDatabase（）;
    ContentValues​​ CV =新ContentValues​​（）;
    cv.put（姓名，l.getName（））;
    cv.put（密码，l.getPassword（））;
    长ID = db.insert（TABLE_NAME，空，CV）;
    db.close（）;
    返回ID;
}

LOGIN类的getter和setter 

 包com.example.logintp;公共类登录{    私人字符串名称，密码;    市民登录（）{}    市民登录（字符串名称，字符串密码）{
        名称= this.name;
        密码= this.password;
    }    公共字符串的getName（）{
        返回名称;
    }    公共无效setname可以（字符串名称）{
        this.name =名称;
    }    公共字符串getPassword来（）{
        返回密码;
    }    公共无效setPassword（字符串密码）{
        this.password =密码;
    }}
包com.example.logintp;公共类登录{    私人字符串名称，密码;    市民登录（）{}    市民登录（字符串名称，字符串密码）{
        名称= this.name;
        密码= this.password;
    }    公共字符串的getName（）{
        返回名称;
    }    公共无效setname可以（字符串名称）{
        this.name =名称;
    }    公共字符串getPassword来（）{
        返回密码;
    }    公共无效setPassword（字符串密码）{
        this.password =密码;
    }}


解决方案

您为您的登录类构造函数向后分配的领域。

 市民登录（字符串名称，字符串密码）{
        名称= this.name;
        密码= this.password;
    }

应

 市民登录（字符串名称，字符串密码）{
        this.name =名称;
        this.password =密码;
    }

因为这个用户名和密码字段将始终保持为空。

I am creating a simple app to add name and password to the database. But when i debugged mu app the name and password field are showing null eventhough i have entered values in the textxbox

MAIN CLASS

package com.example.logintp;

    import java.util.List;

    import android.R.layout;
    import android.app.Activity;
    import android.os.Bundle;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.TextView;

    import com.example.logintp.R.id;

    public class MainDB extends Activity {
        TextView name, password,show1;
        EditText etname, etpassword;
        Button save,show;
        String s1, s2;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            final DbClass db = new DbClass(this);
            name = (TextView) findViewById(R.id.name);
            password = (TextView) findViewById(R.id.password);
            show1=(TextView) findViewById(R.id.show);
            etname = (EditText) findViewById(R.id.etName);
            etpassword = (EditText) findViewById(id.etPassword);
            save = (Button) findViewById(R.id.save);
            show=(Button) findViewById(R.id.Display);
    save.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    // TODO Auto-generated method stub
                    s1 = etname.getText().toString();
                    s2 = etpassword.getText().toString();
                    long id = db.insertData(new Login(s1, s2));
                    if (id < 0) {
                        CommonFunctions.display(MainDB.this, "unsucessful");

                    }else{
                        CommonFunctions.display(MainDB.this, "sucessful");
                    }

                }
            });


        }


    }

DATABASEHANDLER CLASS

package com.example.logintp;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DbClass extends SQLiteOpenHelper {

private static final String db_name = "LoginDetails";
private static final String table_name = "Login";
private static final String name = "name";
private static final String password = "password";
private static final int db_version = 1;
private static final String Create_Table = " CREATE TABLE " + table_name
        + "(" + name + " VARCHAR(200)," + password + " VARCHAR(200)"
        + " ) ";

public DbClass(Context context) {
    super(context, db_name, null, db_version);
}

public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL(Create_Table);

}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    // TODO Auto-generated method stub

}

public long insertData(Login l) {

    SQLiteDatabase db = getWritableDatabase();
    ContentValues cv = new ContentValues();
    cv.put(name, l.getName());
    cv.put(password, l.getPassword());
    long id = db.insert(table_name, null, cv);
    db.close();
    return id;
}

LOGIN CLASS FOR GETTER AND SETTER

package com.example.logintp;

public class Login {

    private String name,password;

    public Login(){}

    public Login(String name,String password){
        name=this.name;
        password=this.password;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}
package com.example.logintp;

public class Login {

    private String name,password;

    public Login(){}

    public Login(String name,String password){
        name=this.name;
        password=this.password;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

解决方案

Your constructor for your Login class is assigning your fields backwards.

public Login(String name,String password){
        name = this.name;
        password = this.password;
    }

should be

public Login(String name,String password){
        this.name = name;
        this.password = password;
    }

because of this your name and password fields will always remain null.

这篇关于越来越插入空值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IT屋！

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