Question

所以我做了一些研究，并在通过代码将按钮定义为对象后

private Button buttonname;
buttonname = (Button) findViewById(R.id.buttonnameinandroid) ;

这是我的问题

buttonname.setOnClickListener(this); //as I understand it, the "**this**" denotes the current `view(focus)` in the android program

然后是您的OnClick()活动......

问题：

当我输入“this”时，它会说：

setOnClickListener (Android.View.view.OnClickListener) in View cannot be applied to (com.helloandroidstudio.MainActivity)

我不知道为什么？

这是.java文件中的代码

import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

    private Button btnClick;
    private EditText Name, Date;
    private TextView msg, NameOut, DateOut;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btnClick = (Button) findViewById(R.id.button) ;
        btnClick.setOnClickListener(this);
        Name = (EditText) findViewById(R.id.textenter) ;
        Date = (EditText) findViewById(R.id.editText) ;
        msg = (TextView) findViewById(R.id.txtviewOut) ;
        NameOut = (TextView) findViewById(R.id.txtoutName) ;
        DateOut = (TextView) findViewById(R.id.txtOutDate) ;
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }
    }

    public void onClick(View v)
    {
        if (v == btnClick)
        {
            if (Name.equals("") == false && Date.equals("") == false)
            {
                NameOut = Name;
                DateOut = Date;
                msg.setVisibility(View.VISIBLE);
            }
            else
            {
                msg.setText("Please complete both fields");
                msg.setVisibility(View.VISIBLE);
            }
        }
        return;

    }

Answer 1

View中的SetOnClickListener（Android.View.view.OnClickListener）不能适用于（com.helloandroidstudio.MainActivity）

换句话说，这意味着（由于您当前的情况）您的MainActivity需要实现 OnClickListener ：

public class Main extends ActionBarActivity implements View.OnClickListener {
   // do your stuff
}

此：

buttonname.setOnClickListener(this);

表示您要为此实例上的Button “分配侦听器 ->此实例代表 OnClickListener ，因此您的类必须实现那个界面。

它与匿名监听器类（您也可以使用）类似：

buttonname.setOnClickListener(new View.OnClickListener() {

   @Override
   public void onClick(View view) {

   }
});

Answer 2

package com.mani.smsdetect;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity implements View.OnClickListener {

    //Declaration Button
    Button btnClickMe;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Intialization Button

        btnClickMe = (Button) findViewById(R.id.btnClickMe);

        btnClickMe.setOnClickListener(MainActivity.this);
        //Here MainActivity.this is a Current Class Reference (context)
    }

    @Override
    public void onClick(View v) {

        //Your Logic
    }
}

Answer 3

Button button= (Button)findViewById(R.id.buttonId);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
    // click handling code
   }
});

Answer 4

以这种方式定义OnClickListener（或任何侦听器）时

btnClick.setOnClickListener(this);

您需要implement OnClickListener Activity。

public class MainActivity extends ActionBarActivity implements OnClickListener{

Answer 5

public class MainActivity extends AppCompatActivity implements View.OnClickListener

每当您对点击事件使用（this）时，您的主要活动必须实现ocClickListener。 Android Studio为您完成此操作，按下alt +输入＆＃39;这个＆＃39;字。

Answer 6

package com.mani.helloworldapplication;

import android.app.Activity;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements View.OnClickListener {
    //Declaration
    TextView tvName;
    Button btnShow;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        //Empty Window
        super.onCreate(savedInstanceState);
        //Load XML File
        setContentView(R.layout.activity_main);

        //Intilization
        tvName = (TextView) findViewById(R.id.tvName);
        btnShow = (Button) findViewById(R.id.btnShow);

        btnShow.setOnClickListener(this);

    }

    @Override
    public void onClick(View v)
    {
        String name = tvName.getText().toString();
        Toast.makeText(MainActivity.this,name,Toast.LENGTH_SHORT).show();
    }
}

Answer 7

启动OnClickListener，但是当您到达第一个设置括号时，键入new，然后键入View，然后按Enter键。当你完成时应该是这样的：

Button btn1 = (Button)findViewById(R.id.button1);

btn1.setOnClickListener(new View.OnClickListener() {            
    @Override
    public void onClick(View v) {
//your stuff here.
    }
});

Answer 8

//据我所知，“this”表示android程序中的当前视图（焦点）

不，“此”仅在MainActivity引用的this实现View.OnClickListener时才有效，setOnClickListener()是View.OnClickListener方法的参数类型。这意味着您应该在MainActivity中实施{{1}}。

Answer 9

您可以简单地在按钮上设置 onClickListener 或使用 Lambda 表达式的任何内容，如下所示

private Button buttonname;
buttonname = (Button)findViewById(R.id.buttonnameinandroid);

buttonname.setOnClickListener(v ->
    {
       //Your Listener Code Here
    });

Answer 10

public class MainActivity extends Activity {

    Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button = (Button) findViewById(R.id.submitButton);
        button.setOnClickListener(new MyClass());

    }

    public class MyClass implements View.OnClickListener {

        @Override
        public void onClick(View v) {

        }

    }
}

Answer 11

在Activity java类中，首先需要一个方法来查找按钮的视图：

btnSum =(Button)findViewById(R.id.button);

在点击监听器上设置

之后

btnSum.setOnClickListener(new View.OnClickListener() {

并覆盖你的功能的onClick方法。我在这里找到了一个完整的例子：http://javainhouse.blogspot.in/2016/01/button-example-android-studio.html

Answer 12

您的Activity必须实施View.OnClickListener，如下所示：

public class MainActivity extends 
Activity implements View.OnClickListener{
// YOUR CODE
}

在MainActivity内覆盖方法onClick()，如下所示：

@override
public void onClick (View view){
//here YOUR Action response to Click Button 
}

Answer 13

您什么也不需要做，只需在new View.OnClickListener()中输入btnClick.setOnClickListener()。我的意思是你必须输入 btnClick.setOnClickListener(new View.onClickListener括号将保持打开状态，只需按Enter即可创建一个这样的方法

btnClick.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

这仅意味着您正在创建OnClickListener的新视图并传递视图作为参数。现在，您可以使用该onClick（View v）方法执行您应做的事情。

Answer 14

处理按钮事件的不同方法

Button btn1 = (Button)findViewById(R.id.button1);
btn1.setOnClickListener(new View.OnClickListener() {            
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Toast.makeText(context, "Button 1", 
     Toast.LENGTH_LONG).show();
        }
    });

[Check this article for more details about button event handlers]

Answer 15

public class EditProfile extends AppCompatActivity {

    Button searchBtn;
    EditText userName_editText;
    EditText password_editText;
    EditText dob_editText;
    RadioGroup genderRadioGroup;
    RadioButton genderRadioBtn;
    Button editBtn;
    Button deleteBtn;
    Intent intent;
    DBHandler dbHandler;

    public static final String USERID_EDITPROFILE = "userID";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_edit_profile);

        searchBtn = (Button)findViewById(R.id.editprof_searchbtn);
        userName_editText = (EditText)findViewById(R.id.editprof_userName);
        password_editText = (EditText)findViewById(R.id.editprof_password);
        dob_editText = (EditText)findViewById(R.id.editprof_dob);
        genderRadioGroup = (RadioGroup)findViewById(R.id.editprof_radiogroup);
        editBtn = (Button)findViewById(R.id.editprof_editbtn);
        deleteBtn = (Button)findViewById(R.id.editprof_deletebtn);
        intent = getIntent();


        dbHandler = new DBHandler(EditProfile.this);

        setUserDetails();

        deleteBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String username = userName_editText.getText().toString();

                if(username == null){
                    Toast.makeText(EditProfile.this,"Please enter username to delete your profile",Toast.LENGTH_SHORT).show();
                }
                else{
                    UserProfile.Users users = dbHandler.readAllInfor(username);

                    if(users == null){
                        Toast.makeText(EditProfile.this,"No profile found from this username, please enter valid username",Toast.LENGTH_SHORT).show();
                    }
                    else{
                        dbHandler.deleteInfo(username);
                        Intent redirectintent_home = new Intent("com.modelpaper.mad.it17121002.Home");
                        startActivity(redirectintent_home);
                    }
                }
            }
        });

        editBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                String userID_String = intent.getStringExtra(Home.USERID);
                if(userID_String == null){
                    Toast.makeText(EditProfile.this,"Error!!",Toast.LENGTH_SHORT).show();
                    Intent redirectintent_home =  new Intent(getApplicationContext(),Home.class);
                    startActivity(redirectintent_home);
                }
                int userID = Integer.parseInt(userID_String);

                String username = userName_editText.getText().toString();
                String password = password_editText.getText().toString();
                String dob = dob_editText.getText().toString();
                int selectedGender = genderRadioGroup.getCheckedRadioButtonId();
                genderRadioBtn = (RadioButton)findViewById(selectedGender);
                String gender = genderRadioBtn.getText().toString();

                UserProfile.Users users = UserProfile.getProfile().getUser();
                users.setUsername(username);
                users.setPassword(password);
                users.setDob(dob);
                users.setGender(gender);
                users.setId(userID);

                dbHandler.updateInfor(users);
                Toast.makeText(EditProfile.this,"Updated Successfully",Toast.LENGTH_SHORT).show();
                Intent redirectintent_home = new Intent(getApplicationContext(),Home.class);
                startActivity(redirectintent_home);
            }
        });

        searchBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               String username = userName_editText.getText().toString();
               if (username == null){
                   Toast.makeText(EditProfile.this,"Please enter a username",Toast.LENGTH_SHORT).show();
               }
               else{
                   UserProfile.Users users_search = dbHandler.readAllInfor(username);


                   if(users_search == null){
                       Toast.makeText(EditProfile.this,"Please enter a valid username",Toast.LENGTH_SHORT).show();
                   }
                   else{
                       userName_editText.setText(users_search.getUsername());
                       password_editText.setText(users_search.getPassword());
                       dob_editText.setText(users_search.getDob());
                       int id = users_search.getId();
                       Intent redirectintent = new Intent("com.modelpaper.mad.it17121002.EditProfile");
                       redirectintent.putExtra(USERID_EDITPROFILE,Integer.toString(id));
                       startActivity(redirectintent);
                   }
               }
            }
        });


    }

    public void setUserDetails(){

        String userID_String = intent.getStringExtra(Home.USERID);
        if(userID_String == null){
            Toast.makeText(EditProfile.this,"Error!!",Toast.LENGTH_SHORT).show();
            Intent redirectintent_home = new Intent("com.modelpaper.mad.it17121002.Home");
            startActivity(redirectintent_home);
        }
        int userID = Integer.parseInt(userID_String);
        UserProfile.Users users = dbHandler.readAllInfor(userID);
        userName_editText.setText(users.getUsername());
        password_editText.setText(users.getPassword());
        dob_editText.setText(users.getDob());
    }
}

如何在android studio中添加按钮点击事件

15 个答案: