Question

用于更改行的更新方法，但是它不能正常工作，结果显示像我们添加数据一样，但是我想更改表的行，但是它无法正常工作。

public int UpdateUserDetails(String name, String location, String designation ,String id) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues cVals = new ContentValues();
    cVals.put(KEY_ID,id);
    cVals.put(KEY_NAME,name);
    cVals.put(KEY_LOC, location);
    cVals.put(KEY_DESG, designation);
    int count = db.update(TABLE_Users, cVals, KEY_ID+ "= ?",new String[{id});

    return  count;
}

主要活动类

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
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 VladimirPutin extends AppCompatActivity {
    EditText name, loc, desig, Sno;
    Button saveBtn, updateBtn;
    Intent intent;
    Toolbar toolbar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("Home Page");
        toolbar.setNavigationContentDescription("Nevigation icon");

        name = (EditText) findViewById(R.id.editname);
        loc = (EditText) findViewById(R.id.editlocation);
        desig = (EditText) findViewById(R.id.editdesignation);
        Sno = (EditText) findViewById(R.id.serialid);
        saveBtn = (Button) findViewById(R.id.add);
        updateBtn = (Button) findViewById(R.id.update);
        saveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = name.getText().toString() + "\n";
                String location = loc.getText().toString();
                String designation = desig.getText().toString();
                DataBaseHelper dbHandler = new DataBaseHelper(VladimirPutin.this);
                dbHandler.insertUserDetails(username, location, designation);
                intent = new Intent(VladimirPutin.this, DetailsActivity.class);
                startActivity(intent);
                Toast.makeText(getApplicationContext(), "Details Inserted Successfully", Toast.LENGTH_SHORT).show();
            }
        });
        updateBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String  snumber=Sno.getText().toString()+"\n";
                String username = name.getText().toString();
                String location = loc.getText().toString();
                String designation = desig.getText().toString();
                DataBaseHelper dbHandler = new DataBaseHelper(VladimirPutin.this);
                dbHandler.UpdateUserDetails(username, location, designation,snumber);
                intent = new Intent(VladimirPutin.this, DetailsActivity.class);
                startActivity(intent);
                Toast.makeText(getApplicationContext(), "Details updated  Successfully", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

虽然我使用Cursor类来获取数据库中的值，但是我花了一个星期的时间在这个项目上工作，但不知道我会在哪里出错。

Answer 1

用更新方法调用替换下面的行
int count = db.update（TABLE_Users，cVals，KEY_ID +“ =” + id，null）;

并删除行cVals.put（KEY_ID，id）;

Answer 2

首先可能是语法错误。我建议将KEY_ID+ "= ?"更改为KEY_ID+ "=?"。这意味着new String[{id}是什么意思？奇怪的代码。

为什么数据库中没有更新我的行？

2 个答案: