如何在android中从警报对话框添加字符串？

我在用安卓。现在我有问题了。我创建了一个progrm，它将通过一个警报对话框从用户那里获取字符串。并将其添加到微调器中。但它在logcat中显示了一些异常。请任何人帮我解决这个问题。这是我的代码

**MainActivity.java**

package com.example.picker;

import java.util.ArrayList;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.text.Editable;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;

public class MainActivity extends Activity {
   Button add_button;

   Editable value;
   String inserted_value;
   AlertDialog.Builder alert;
   Spinner spinner;

   /** Items entered by the user is stored in this ArrayList variable */
   ArrayList<String> list = new ArrayList<String>();

   /** Declaring an ArrayAdapter to set items to ListView */
   ArrayAdapter<String> adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        add_button = (Button)findViewById(R.id.addbutton);
        alert = new AlertDialog.Builder(this);
        final EditText input = new EditText(this);

         /** Getting a reference to Spinner object of the resource activity_main */
        spinner = (Spinner) findViewById(R.id.spin1);

        add_button.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                alert.setTitle("Picker");
                alert.setMessage("Enter a string...");

                // Set an EditText view to get user input 

                alert.setView(input);

                alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
if(inserted_value !=null){

                       Log.d("GOT_TEXT",inserted_value);
                       list.add(input.getText().toString());
                     }
                    else{
                        Log.d("GOT_TEXT","inserted_value is null"); 
                     }


                    /** Setting the adapter to the ListView */
                    spinner.setAdapter(adapter);

                    /** Adding radio buttons for the spinner items */
                    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

                  }
                });

                alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                  public void onClick(DialogInterface dialog, int whichButton) {
                    // Canceled.
                      dialog.dismiss();
                  }
                });

                alert.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.activity_main, menu);
        return true;
    }

}

试试看：

if(inserted_value !=null){

   Log.d("GOT_TEXT",inserted_value); 
 }
else{
    Log.d("GOT_TEXT","inserted_value is null"); 
 }

因为当您尝试记录时，

插入的\u值

为空

请尝试此操作

if(input.getText().length() != 0)
{
list.add(input.getText().toString());
}else{
}

---

在logcat01-28 13:33:55.187:E/AndroidRuntime（673）中获得另一个异常：致命异常：main 01-28 13:33:55.187:E/AndroidRuntime（673）：java.lang.NullPointerException 01-28 13:33:55.187:E/AndroidRuntime（673）：在com.example.picker.MainActivity$1.lickonc（MainActivity.java:76）01-28 13:33:55.187:E/AndroidRuntime（673）：在com.android.internal.app.AlertController$ButtonHandler.handleMessage（AlertController.java:158）嘿，现在我的logcat@agen451：确定使用最新错误日志编辑您的问题，并code@agen451：您将需要替换

alert.show（）带有
AlertDialog AlertDialog=alert.create（）；alertDialog.show（）
if(input.getText().length() != 0)
{
list.add(input.getText().toString());
}else{
}