我需要关闭我的 PopupWindow，但关闭功能不起作用

【问题标题】：I need to dismiss my PopupWindow, but the dismiss function isn't working我需要关闭我的 PopupWindow，但关闭功能不起作用
【发布时间】：2014-04-22 18:10:06
【问题描述】：

标题描述得很好；弹出窗口打开，并用作我的游戏的菜单。但是，当我尝试使用按钮关闭菜单时，Eclipse 说“局部变量 pw 可能尚未初始化”：\

我的 Java 代码：

package com.bipbapapps.leagueclickerapp;


import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Typeface;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.PopupWindow;
import android.widget.PopupWindow.OnDismissListener;
import android.widget.TextView;

public class MainClass extends Activity implements OnClickListener {

public float goldCount;
Button minionClick;
Button storeClick;
Button storeDismiss;
TextView textGoldCount;
String textTotal;
private SharedPreferences prefs;

@Override
public void onCreate (Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //Set full-screen
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(R.layout.mainlayout);

    prefs = getSharedPreferences("LeagueClicker", Context.MODE_PRIVATE);


    goldCount = prefs.getFloat("goldCount", 0.0f);

    //Linking the variables
    minionClick = (Button) findViewById(R.id.minioncentreid);
    storeClick = (Button) findViewById(R.id.storeimageid);
    storeDismiss = (Button) findViewById(R.id.menudismissid);
    textGoldCount = (TextView) findViewById(R.id.textviewtop);

    //String which will display at the top of the app
    textTotal = goldCount + " Gold";

    //Setting TextView to the String
    textGoldCount.setText(textTotal);
    textGoldCount.setGravity(Gravity.CENTER);
    Typeface tf = Typeface.createFromAsset(getAssets(), "mechanical.ttf");
    textGoldCount.setTypeface(tf);
    textGoldCount.setTextSize(35);

    //Setting onClickListener
    minionClick.setOnClickListener(this);
    storeClick.setOnClickListener(this);
    storeDismiss.setOnClickListener(this);


}


@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId()){
    case R.id.minioncentreid:
    goldCount += 1.0;
    prefs.edit().putFloat("goldCount", goldCount).commit();
    textTotal = goldCount + " Gold";
    textGoldCount.setText(textTotal);
    textGoldCount.setGravity(Gravity.CENTER);
    break;

    case R.id.storeimageid:
        LayoutInflater inflater = (LayoutInflater)
           this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        PopupWindow pw = new PopupWindow(
           inflater.inflate(R.layout.storemenu, null, false), 
           300, 
           450, 
           true);
        pw.showAtLocation(v, Gravity.CENTER, 0, 0);

    case R.id.menudismissid:
        pw.dismiss();
        break;

    }


}


@Override
public void onPause(){
    super.onPause();
    prefs.edit().putFloat("goldCount", goldCount).commit();
}

@Override
public void onResume(){
    super.onResume();
    goldCount = prefs.getFloat("goldCount", 0.0f);
}

@Override
public void onStop(){
    super.onStop();
    prefs.edit().putFloat("goldCount", goldCount).commit();
    Log.d(prefs.getFloat("goldCount", 0.0f)+"derprolw", "ejwfjbrea");
}

}

有谁知道如何设置按钮以关闭 PopupWindow？

编辑：现在产生的 LogCat 错误：

04-22 15:20:04.478: E/AndroidRuntime(3491): FATAL EXCEPTION: main
04-22 15:20:04.478: E/AndroidRuntime(3491): Process: com.bipbapapps.leagueclickerapp, PID: 3491
04-22 15:20:04.478: E/AndroidRuntime(3491): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bipbapapps.leagueclickerapp/com.bipbapapps.leagueclickerapp.MainClass}: java.lang.NullPointerException
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.os.Looper.loop(Looper.java:136)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at java.lang.reflect.Method.invokeNative(Native Method)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at java.lang.reflect.Method.invoke(Method.java:515)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at dalvik.system.NativeStart.main(Native Method)
04-22 15:20:04.478: E/AndroidRuntime(3491): Caused by: java.lang.NullPointerException
04-22 15:20:04.478: E/AndroidRuntime(3491):     at com.bipbapapps.leagueclickerapp.MainClass.onCreate(MainClass.java:66)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.Activity.performCreate(Activity.java:5231)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-22 15:20:04.478: E/AndroidRuntime(3491):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)

编辑 2：

所以，在一些帮助和编辑下，我们找到了代码：

//Initialize variables from popup window
     LayoutInflater inflater = (LayoutInflater)
           this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    PopupWindow pw = new PopupWindow(
               inflater.inflate(R.layout.storemenu, null, false)); 
    storeDismiss = (Button) pw.getContentView().findViewById(R.id.menudismissid);

代替“storeDismiss = (Button) findViewById(R.id.menudismissid);”。现在唯一的问题是按钮实际上并没有关闭菜单:(

【问题讨论】：

  • 您是否在case R.id.storeimageid 末尾和case R.id.menudismissid 之前缺少break;？ Eclipse 在抱怨哪一行？

标签： java android dismiss android-popupwindow


【解决方案1】：

我认为您不能在另一个案例块中使用在一个案例块中定义的变量。因为 case 块没有特定的执行顺序。更好的方法是，将PopupWindow 声明为类的成员变量。

public class MainClass extends Activity implements OnClickListener {

public float goldCount;
Button minionClick;
Button storeClick;
Button storeDismiss;
TextView textGoldCount;
String textTotal;
private SharedPreferences prefs;
PopupWindow pw;

@Override
public void onCreate (Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //Set full-screen
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(R.layout.mainlayout);

    prefs = getSharedPreferences("LeagueClicker", Context.MODE_PRIVATE);


    goldCount = prefs.getFloat("goldCount", 0.0f);

    //Linking the variables
    minionClick = (Button) findViewById(R.id.minioncentreid);
    storeClick = (Button) findViewById(R.id.storeimageid);
    storeDismiss = (Button) findViewById(R.id.menudismissid);
    textGoldCount = (TextView) findViewById(R.id.textviewtop);

    //String which will display at the top of the app
    textTotal = goldCount + " Gold";

    //Setting TextView to the String
    textGoldCount.setText(textTotal);
    textGoldCount.setGravity(Gravity.CENTER);
    Typeface tf = Typeface.createFromAsset(getAssets(), "mechanical.ttf");
    textGoldCount.setTypeface(tf);
    textGoldCount.setTextSize(35);

    //Setting onClickListener
    minionClick.setOnClickListener(this);
    storeClick.setOnClickListener(this);
    storeDismiss.setOnClickListener(this);


}


@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId()){
    case R.id.minioncentreid:
    goldCount += 1.0;
    prefs.edit().putFloat("goldCount", goldCount).commit();
    textTotal = goldCount + " Gold";
    textGoldCount.setText(textTotal);
    textGoldCount.setGravity(Gravity.CENTER);
    break;

    case R.id.storeimageid:
        LayoutInflater inflater = (LayoutInflater)
           this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        if(pw == null) {
        pw = new PopupWindow(
           inflater.inflate(R.layout.storemenu, null, false), 
           300, 
           450, 
           true);
        }
        pw.showAtLocation(v, Gravity.CENTER, 0, 0);
         break;

    case R.id.menudismissid:
        if (pw != null) {
        pw.dismiss();
        }
        break;

    }

也不要忘记将break 语句放在第一个案例块的末尾:)

编辑 1： 您可以通过

访问PopUpWindow的视图元素 
//Linking the variables
minionClick = (Button) findViewById(R.id.minioncentreid);
storeClick = (Button) findViewById(R.id.storeimageid);
textGoldCount = (TextView) findViewById(R.id.textviewtop);

//Initialize variables from popup window
 LayoutInflater inflater = (LayoutInflater)
       this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
PopupWindow pw = new PopupWindow(
           inflater.inflate(R.layout.storemenu, null, false), 
storeDismiss = pw.getContentView().findViewById(R.id.menudismissid);

编辑 2：

dismiss 函数的官方文档说

public voiddismiss()

在 API 级别 1 Dispose 的弹出窗口中添加。这种方法可以 仅在 showAsDropDown(android.view.View) 之后调用 执行。否则，调用此方法将无效。

所以你的案例 2 的代码应该是

case R.id.storeimageid:
        LayoutInflater inflater = (LayoutInflater)
           this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        if(pw == null) {
        pw = new PopupWindow(
           inflater.inflate(R.layout.storemenu, null, false), 
           300, 
           450, 
           true);
        }
        pw.showAsDropDown(v, 0, 0, Gravity.CENTER);
         break;

【讨论】：

  • 它似乎不起作用：\ 这消除了错误，但随后我的应用程序在加载时崩溃。
  • 你能发布异常的LogCat跟踪吗？
  • 第 66 行是哪一行？在 logcat at com.bipbapapps.leagueclickerapp.MainClass.onCreate(MainClass.java:66) 中双击此语句。它将显示导致NullPointerException的代码行
  • 该行是“storeDismiss.setOnClickListener(this);”。我一直在搞乱代码，但我什么也想不通 - 仍然没有错误，但应用程序在加载时崩溃了。
  • 似乎storeDismiss 为空。你确定在mainlayout 中有id 为menudismissid 的按钮吗？你能把mainlayout.xml文件的代码贴出来吗？
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