Android Studio上的Toast的按钮单击事件错误

Question

此代码无法在Android Studio上运行。 我只希望它在单击按钮时显示一个吐司。 请帮忙。 代码如下：

我是android开发的新手，很难解决这个问题。 我认为问题是一个愚蠢的语法错误或未定义变量。 另外，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

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

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

Answer 1

v == mSubmitButton是错误的在Java中，只能与操作符==等同于基本类型。 对于对象，您需要使用equals（）方法。 更换：

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();
        }
    }
    }

Answer 2

尝试以下代码：

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

Answer 3

我想你不需要检查

 @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();
    //}
}

Answer 4

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);
}
}  

Answer 5

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();
    }

});

用这个。 无需检查if(v.getId() == R.id.btnSubmit) 。 因为您要将点击动作设置为已初始化的按钮。

Answer 6

您应该使用设置器来设置onclickListener。 而且，当您使用新的onclicklistener时，只需将其设置为按钮，就无需检查v == mSubmitButton了，因为无论如何这是唯一的选择:)

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();

    }

Answer 7

 mSubmitButton.OnClickListener(

应该

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();
    }
});

Answer 8

用getApplicationContext（）替换“ this”

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

}

Answer 9

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();

        }
    });

Answer 10

您的语法中括号放错了位置，并且缺少了; 以及拼写错误的setOnClickListener方法名称。

更改

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

至

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