带按钮的Android Eclipse弹出消息

Question

我想这样做,只需点击一下按钮,就会出现一条弹出消息.

现在,只要我打开应用程序,弹出窗口就会出现.

BTW我想要触发弹出窗口的按钮是main.xml中的about按钮

这是我的main.xml(带有布局的东西):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/main"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#3DE400"
    android:orientation="vertical" >

    <!-- background originally #d78a00 -->

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="60dp"
        android:fontFamily="sans-serif-condensed"
        android:paddingLeft="10dp"
        android:text="Sample App"
        android:textColor="#FFF"
        android:textSize="60sp" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:fontFamily="sans-serif-condensed"
        android:paddingLeft="10dp"
        android:text="@string/creator"
        android:textColor="#FFF"
        android:textSize="20dp" />

    <Button
        android:id="@+id/about"
        android:layout_width="123dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:background="@android:color/transparent"
        android:fontFamily="sans-serif-condensed"
        android:gravity="left"
        android:paddingLeft="10dp"
        android:text="@string/about"
        android:textColor="#FFF"
        android:textSize="40dp"
        android:onClick="show" />

</LinearLayout>

这是我的MainActivity.java:

package com.pranavsanghvi.sampleappv4;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.view.Menu;
import android.widget.Toast;
import android.content.DialogInterface;
import android.view.View;
import android.widget.Button;


public class MainActivity extends Activity {

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

        AlertDialog.Builder alert = new AlertDialog.Builder(MainActivity.this);
        alert.setTitle("About");
        alert.setMessage("Sample About");
        alert.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            public void onClick (DialogInterface dialog, int id) {
                Toast.makeText (MainActivity.this, "Success", Toast.LENGTH_SHORT) .show();
            }
        });
        alert.setNegativeButton("No", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                Toast.makeText(MainActivity.this, "Fail", Toast.LENGTH_SHORT) .show();
            }
        });
        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.main, menu);
        return true;
    }

}

Answer 1

如果您想在“关于”按钮上显示弹出窗口，请单击添加以下内容onCreate()

Button aboutButton = (Button) findViewById(R.id.about);
aboutButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                alert.show();
            }
        });

alert.show();只需从 onCreate() 中删除即可；

更新 ：-

您是否收到无法解决的警报？如果是这样，那么要么将警报设置为全局，即在外部声明它onCreate()

public class MainActivity extends Activity {
    AlertDialog.Builder alert;
@Override
    protected void onCreate(Bundle savedInstanceState) {
// code
alert = new AlertDialog.Builder(MainActivity.this);
// code

或者将其定为最终的

final AlertDialog.Builder alert = new AlertDialog.Builder(MainActivity.this);

也删除alert.show();其中的onCreate();