java - 捕获对话框中按钮的单击事件

Question

我刚刚开始学习Android编程。我正在编写我的第一个应用程序。这有一个按钮(添加新 friend )，我捕获了一个点击事件。这意味着当单击此按钮时，应用程序将显示一个对话框。在对话框中还有一个按钮(添加)。我想在单击此按钮时捕获单击事件。我使用 View.OnClickListener() 来捕获这个。但不幸的是，当我单击按钮添加新 friend 时，该应用程序。这是我的代码:MainActivity.java:

package com.example.helloworld;
import java.util.ArrayList;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;


@SuppressWarnings("deprecation")
public class MainActivity extends ActionBarActivity {

    private Button addNewStudent;
    public  static ArrayList<Student> listStudent;

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

        listStudent= new ArrayList<Student>();

        addNewStudent= (Button) (findViewById(R.id.btAdd));
        addNewStudent.setOnClickListener(new  OnClickListener(){

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                //Toast.makeText(getApplicationContext(), "This is a toast", Toast.LENGTH_SHORT).show();
//              Student sv= new Student("Nguyen Van A", 19);
//              listStudent.add(sv);

                MyDialog dialog= new MyDialog(MainActivity.this);
                dialog.show();

//              Toast.makeText(getApplicationContext(), sv.getName()+" "+ sv.getAge(), Toast.LENGTH_SHORT).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.main, menu);
        return true;
    }

    @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);
    }
}

MyDialog.java:

package com.example.helloworld;

import android.app.Dialog;
import android.content.Context;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.view.View.OnClickListener;
public class MyDialog extends Dialog{

    Button buttonAddStudent;
    Button buttonCancel;
    EditText etName;
    EditText etAge;

    public MyDialog(Context context){
        super(context);

        buttonAddStudent= (Button) findViewById(R.id.buttonAdd);    
        buttonCancel= (Button) findViewById(R.id.buttonCancel);
        etName= (EditText) findViewById(R.id.editTextName);
        etAge= (EditText) findViewById(R.id.editTextAge);

        buttonAddStudent.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String name= etName.getText().toString();
                int age= Integer.valueOf(etAge.getText().toString());

                Student sv= new Student(name, age);
                MainActivity.listStudent.add(sv);

                //Toast.makeText(getContext(), MainActivity.listStudent.toString(), Toast.LENGTH_SHORT).show();

            }
        });

        setTitle("Add new student");
        setContentView(R.layout.dialog_layout);
    }
}

感谢您对此的想法:)

Answer 1

您应该在调用 findViewById 之前设置对话框的内容
试试这个:

public MyDialog(Context context){
    super(context);

    setContentView(R.layout.dialog_layout);
    setTitle("Add new student");

    buttonAddStudent= (Button) findViewById(R.id.buttonAdd);    
    buttonCancel= (Button) findViewById(R.id.buttonCancel);
    etName= (EditText) findViewById(R.id.editTextName);
    etAge= (EditText) findViewById(R.id.editTextAge);

    buttonAddStudent.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            String name= etName.getText().toString();
            int age= Integer.valueOf(etAge.getText().toString());

            Student sv= new Student(name, age);
            MainActivity.listStudent.add(sv);

            //Toast.makeText(getContext(), MainActivity.listStudent.toString(), Toast.LENGTH_SHORT).show();

        }
    });

}