android studio上toast的按钮单击事件错误答案

【问题标题】：Button click event error for toast on android studioandroid studio上toast的按钮单击事件错误
【发布时间】：2014-12-11 10:55:15
【问题描述】：

此代码无法在 Android Studio 上运行。我只是希望它在单击按钮时显示吐司。请帮忙。下面附上代码：

我是 android 开发的新手，很难弄清楚这一点。我认为问题是一个愚蠢的语法错误或未定义的变量。另外，我如何定义“v”？

package com.shutter2000.www.shutter_2000_oms;    
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
import android.view.View.OnClickListener;    


public class SiteVisitDetails extends Activity {

public EditText mCusName;
public EditText mOrderID;
public EditText mProjectID;
public EditText mHeightWidth;
public EditText mNote;
public Button mSubmitButton;


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

    //initialize text fields
    mCusName = (EditText) findViewById(R.id.txtCusName);
    mOrderID = (EditText) findViewById(R.id.txtOrderID);
    mProjectID = (EditText) findViewById(R.id.txtProjectID);
    mHeightWidth = (EditText) findViewById(R.id.txtHeightWidth);
    mNote = (EditText) findViewById(R.id.txtNote);
    mSubmitButton = (Button) findViewById(R.id.btnSubmit);

    //listen to submit button click event

    mSubmitButton.OnClickListener(new View.OnClickListener())
    {

        @Override
        public void onClick(View v){


        if (v == mSubmitButton) {
            Context context = getApplicationContext();
            CharSequence text = "Successfully Sent!";
            int duration = Toast.LENGTH_LONG;
            final Toast tost = Toast.makeText(context, text, duration);
            tost.show();
        }
    }
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.site_visit_details, menu);
    return true;
}

public void addItemsToProductSpinner() {
    Spinner spinner = (Spinner) findViewById(R.id.spnProducts);
    // Create an ArrayAdapter using the string array and a default spinner layout
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
            R.array.products, android.R.layout.simple_spinner_item);
    // Specify the layout to use when the list of choices appears
    android.R.layout.simple_spinner_item
    // Apply the adapter to the spinner
    spinner.setAdapter(adapter);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

错误是：

“mSubmitButton...”的错误

Expected class or package
'OnClickListener' is abstract;cannot be instantiated

“@override public void onClick(View v){...”的错误

Annotations are not allowed here
Identifier or type expected

“public void addItemsToProductSpinner()...”的错误

";" expected
Cannot resolve symbol "v"
unexpected token

【问题讨论】：

标签： java android

【解决方案1】：

package com.shutter2000.www.shutter_2000_oms;    
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
import android.view.View.OnClickListener;    


public class SiteVisitDetails extends Activity implements OnClickListener{

public EditText mCusName;
public EditText mOrderID;
public EditText mProjectID;
public EditText mHeightWidth;
public EditText mNote;
public Button mSubmitButton;


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

    //initialize text fields
    mCusName = (EditText) findViewById(R.id.txtCusName);
    mOrderID = (EditText) findViewById(R.id.txtOrderID);
    mProjectID = (EditText) findViewById(R.id.txtProjectID);
    mHeightWidth = (EditText) findViewById(R.id.txtHeightWidth);
    mNote = (EditText) findViewById(R.id.txtNote);
    mSubmitButton = (Button) findViewById(R.id.btnSubmit);

    //listen to submit button click event

    mSubmitButton.setOnClickListener(this);

}

@Override
public void onClick(View v) {
     if (v.getId() == R.id.mSubmitButton) {
         Toast.makeText(this,"Successfully sent!",Toast.LENGTH_LONG).show();             
     }

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.site_visit_details, menu);
    return true;
}

public void addItemsToProductSpinner() {
    Spinner spinner = (Spinner) findViewById(R.id.spnProducts);
    // Create an ArrayAdapter using the string array and a default spinner layout
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
            R.array.products, android.R.layout.simple_spinner_item);
    // Specify the layout to use when the list of choices appears
    android.R.layout.simple_spinner_item
    // Apply the adapter to the spinner
    spinner.setAdapter(adapter);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

【讨论】：

您应该在 xml 文件中提及您的按钮的 ID。例如，如果您在 xml 文件中的按钮 id 是 btn_submit。那么你必须检查 v.getId()==R.id.btn_submit
是的，我的错误，它应该是大写的，即 LENGTH_LONG

【解决方案2】：

错了v == mSubmitButton 在 java 中，只能用 operator == 来等于原始类型。对于对象，您需要使用 equals() 方法。替换：

mSubmitButton.onClickListener(new View.OnClickListener())
    {

        @Override
        public void onClick(View v){


        if (v.getId() == R.id.btnSubmit) {
            Context context = getApplicationContext();
            CharSequence text = "Successfully Sent!";
            int duration = Toast.LENGTH_LONG;
            final Toast tost = Toast.makeText(context, text, duration);
            tost.show();
        }
    }
    }

【讨论】：

【解决方案3】：

单击按钮时显示吐司。

    mSubmitButton = (Button) findViewById(R.id.btnSubmit);
    mSubmitButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            //SiteVisitDetails
            Toast tea = Toast.makeText(getApplicationContext(), "Send", Toast.LENGTH_LONG);
            tea.show();

        }
    });

【讨论】：

【解决方案4】：

mSubmitButton.setOnClickListener(new View.OnClickListener())
{
    @Override
    public void onClick(View v){
        CharSequence text = "Successfully Sent!";
        int duration = Toast.LENGTH_LONG;
        Toast tost = Toast.makeText(SiteVisitDetails.this, text, duration);
        tost.show();
    }

});

使用这个。无需检查if(v.getId() == R.id.btnSubmit)。因为您正在为已经初始化的按钮设置点击操作。

【讨论】：

感谢您的回复:)

【解决方案5】：

您的语法中有错误的括号，缺少; 和拼写错误的setOnClickListener 方法名称。

改变

mSubmitButton.OnClickListener(new View.OnClickListener())
    {
    // ...
    }

到

mSubmitButton.setOnClickListener(new View.OnClickListener()
    {
    // ...
    });

【讨论】：

【解决方案6】：

将“this”替换为 getApplicationContext()

@Override
public void onClick(View v) {
 if (v.getId() == R.id.mSubmitButton) {
     Toast.makeText(getApplicationContext(),"Successfully sent!",Toast.Length_LONG).show();             
 }

}

【讨论】：

这给出了错误：“OnClickListener”是抽象的；无法实例化
setOnClickListner 也是使用工作室智能的抽象函数。我希望这种方法也能存在。
@Override public void onClick(View v) { Toast.makeText(getApplicationContext(),"发送成功！",Toast.Length_LONG).show(); } }

【解决方案7】：

 mSubmitButton.OnClickListener(

应该是

mSubmitButton.setOnClickListener(

编辑。 setOnClickListener 方法需要一个实现View.OnClickListener 接口的对象：

mSubmitButton.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v){
        Context context = getApplicationContext();
        CharSequence text = "Successfully Sent!";
        int duration = Toast.LENGTH_LONG;
        final Toast tost = Toast.makeText(context, text, duration);
        tost.show();
    }
});

【讨论】：

两者的结果相同。

【解决方案8】：

您应该使用 setter 来设置 onclickListener。而且由于您使用的是新的 onclicklistener 并且您只是为您的按钮设置它，您不需要检查是否 v==mSubmitButton 因为它是唯一的选择:)

mSubmitButton.setOnClickListener(new View.OnClickListener())
    {

        @Override
        public void onClick(View v){

            Context context = getApplicationContext();
            CharSequence text = "Successfully Sent!";
            int duration = Toast.LENGTH_LONG;
            final Toast tost = Toast.makeText(context, text, duration);
            tost.show();

    }

【讨论】：

很高兴听到它解决了您的问题 :)

【解决方案9】：

我认为你不需要检查

 @Override
    public void onClick(View v){

 //Don't need to check condition control come here only v.getId() == R.id.btnSubmit 
   //  if (v == mSubmitButton) { 

        Context context = getApplicationContext();
        CharSequence text = "Successfully Sent!";
        int duration = Toast.LENGTH_LONG;
        final Toast tost = Toast.makeText(context, text, duration);
        tost.show();
    //}
}

【讨论】：

感谢您的回复:)

【解决方案10】：

试试下面的代码：

if(v.getId() == R.id.btnSubmit){
     Toast.makeText(SiteVisitDetails.this,"Successfully Sent!",Toast.LENGTH_LONG).show();
}

【讨论】：