[英]how to add button click event in android studio
所以我做了一些研究,在通過代碼將你的按鈕定義為一個對象之后
private Button buttonname;
buttonname = (Button) findViewById(R.id.buttonnameinandroid) ;
這是我的問題
buttonname.setOnClickListener(this); //as I understand it, the "**this**" denotes the current `view(focus)` in the android program
然后你的OnClick()
事件...
問題:
當我輸入“this”時,它說:
setOnClickListener (Android.View.view.OnClickListener) in View cannot be applied to (com.helloandroidstudio.MainActivity)
我不知道為什么?
這是 .java 文件中的代碼
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;
}
View中的SetOnClickListener(Android.View.view.OnClickListener)不能應用於(com.helloandroidstudio.MainActivity)
這意味着換句話說(由於您當前的情況)您的 MainActivity 需要實現OnClickListener :
public class Main extends ActionBarActivity implements View.OnClickListener {
// do your stuff
}
這:
buttonname.setOnClickListener(this);
意味着您要為“在此實例上”的Button 分配偵聽器->
此實例代表OnClickListener ,因此您的類必須實現該接口。
它類似於匿名偵聽器類(您也可以使用):
buttonname.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
}
});
Button button= (Button)findViewById(R.id.buttonId);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
// click handling code
}
});
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
}
}
當您以這種方式定義OnClickListener
(或任何偵聽器)時
btnClick.setOnClickListener(this);
您需要在Activity
implement
OnClickListener
。
public class MainActivity extends ActionBarActivity implements OnClickListener{
public class MainActivity extends AppCompatActivity implements View.OnClickListener
每當您在點擊事件上使用 (this) 時,您的主要活動都必須實現 ocClickListener。 Android Studio 會為您完成,在“this”字樣上按 alt+enter。
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();
}
}
啟動您的 OnClickListener,但是當您到達第一個設置括號時,鍵入 new,然后鍵入 View,然后按 Enter。 完成后應該如下所示:
Button btn1 = (Button)findViewById(R.id.button1);
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//your stuff here.
}
});
//據我所知,“this”表示android程序中的當前視圖(焦點)
不,“this”僅在this
引用的MainActivity
實現View.OnClickListener
,這是setOnClickListener()
方法的參數類型。 這意味着您應該在MainActivity
實現View.OnClickListener
。
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) {
}
}
}
您可以簡單地在 Button 或任何使用 Lambda 表達式的東西上設置 onClickListener ,它看起來像
private Button buttonname;
buttonname = (Button)findViewById(R.id.buttonnameinandroid);
buttonname.setOnClickListener(v ->
{
//Your Listener Code Here
});
在 Activity java 類中,您首先需要一個方法來查找按鈕的視圖:
btnSum =(Button)findViewById(R.id.button);
在此設置后單擊偵聽器
btnSum.setOnClickListener(new View.OnClickListener() {
並為您的功能覆蓋 onClick 方法。我在這里找到了一個完整的示例: http : //javainhouse.blogspot.in/2016/01/button-example-android-studio.html
您的Activity
必須實現View.OnClickListener
,如下所示:
public class MainActivity extends
Activity implements View.OnClickListener{
// YOUR CODE
}
在MainActivity
重寫方法onClick()
,如下所示:
@override
public void onClick (View view){
//here YOUR Action response to Click Button
}
您什么都不用做,只需在btnClick.setOnClickListener()
鍵入new View.OnClickListener()
btnClick.setOnClickListener()
。 我的意思是你必須輸入btnClick.setOnClickListener(new View.onClickListener
括號將保持打開狀態,只需按回車鍵,就會像這樣創建一個方法,
btnClick.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
這只是意味着您正在創建 OnClickListener 的新視圖並將視圖作為參數傳遞。 現在你可以在 onClick(View v) 方法中做你應該做的任何事情。
處理按鈕事件的不同方式
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();
}
});
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());
}
}
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