你好，我是android studio的新手.我试图去下一个窗口，但当我点击按钮的应用程序崩溃.这是我的代码

Question

package com.example.getorganized;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import java.util.HashMap;
public class add extends AppCompatActivity {
private  FirebaseAuth firebaseAuth;
private  ProgressDialog progressDialo;
Button cAdd;
EditText cname;
String category = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);
firebaseAuth = FirebaseAuth.getInstance();
progressDialo =new ProgressDialog(this);
progressDialo.setTitle("Please wait");
progressDialo.setCanceledOnTouchOutside(false);
cname.findViewById(R.id.CName);
cAdd.findViewById(R.id.cAdd);
cAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
vaildateData();
}
});
}

private void vaildateData() {
category = cname.getText().toString().trim();
if(category.isEmpty()){
cname.setError("Enter name of Category");
}
else{
addTo();
}
}
private void addTo() {
progressDialo.setMessage("Adding category...");
progressDialo.show();
long timestamp = System.currentTimeMillis();
HashMap<String, Object> hashMap = new HashMap<>();
hashMap.put("id", "" +timestamp);
hashMap.put("category", ""+category);
hashMap.put("timestamp", timestamp);
hashMap.put("uid", ""+ firebaseAuth.getUid());
DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Categories");
ref.child(""+timestamp).setValue(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void unused) {
progressDialo.dismiss();
Toast.makeText(add.this, "Category added successfully", Toast.LENGTH_LONG).show();
}
});
}
}

嗨，我是android studio的新手。我正在尝试创建一个连接到firebase的图书馆管理应用程序。我已经创建了一个登录和注册页面。我现在试图去下一个窗口，但当我点击按钮的应用程序崩溃。这是我的代码。这是它崩溃的活动。如果我删除以下代码，应用程序不会崩溃。请有人帮我一下。

Answer 1

在你的onCreate()方法中，做以下修改

添加

cname = findViewById(R.id.CName);
cAdd = findViewById(R.id.cAdd);

不是

cname.findViewById(R.id.CName);
cAdd.findViewById(R.id.cAdd);