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爲什麼使用TextView更新int值並顯示它給我一個崩潰？

2013-04-21 23 views
0

我試圖爲Android開發文字冒險。已經找到了一種微妙的方式來改變'網頁'而不創建新的活動。爲什麼使用TextView更新int值並顯示它給我一個崩潰？

現在我試圖在每個佈局中包含永久性的int值，這些值在更改後會立即更新。

I.e.黃金/健康價值。根據玩家遊戲中的選擇，它會： - 佈局切換到相應的頁面 - 金+10，健康-1

的變化int值我開發這個代碼在MainActivity類：

package com.example.textadventure; 

import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.TextView; 

public class MainActivity extends Activity { 

    private int int1 = 1; 

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

    public void changelayout1(View view){ 
     setContentView(R.layout.activity_main2); 
     int1 += 1; 
    } 
    public void changelayout2(View view){ 
     setContentView(R.layout.activity_main); 
     int1 += 1; 
    } 
    public void changelayout3(View view){ 
     setContentView(R.layout.activity_main3); 
     int1 += 1; 
    } 



    public void onResume() { 
     super.onResume(); 
     TextView textView = (TextView) this.findViewById(R.id.mytextview1); 
     textView.setText(String.valueOf(int1)); 
    } 



}

結果如下：

我logcat的

04-19 16:09:57.446: E/Trace(3204): error opening trace file: No such file or directory (2) 
04-19 16:09:59.016: D/AndroidRuntime(3204): Shutting down VM 
04-19 16:09:59.016: W/dalvikvm(3204): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
04-19 16:09:59.036: E/AndroidRuntime(3204): FATAL EXCEPTION: main 
04-19 16:09:59.036: E/AndroidRuntime(3204): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.os.Looper.loop(Looper.java:137) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at dalvik.system.NativeStart.main(Native Method) 
04-19 16:09:59.036: E/AndroidRuntime(3204): Caused by: java.lang.NullPointerException 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at com.example.textadventure.MainActivity.onResume(MainActivity.java:28) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.Activity.performResume(Activity.java:5182) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732) 
04-19 16:09:59.036: E/AndroidRuntime(3204):  ... 12 more 
04-19 16:10:02.386: I/Process(3204): Sending signal. PID: 3204 SIG: 9 
04-19 16:15:42.576: D/AndroidRuntime(3292): Shutting down VM 
04-19 16:15:42.586: W/dalvikvm(3292): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
04-19 16:15:42.596: E/AndroidRuntime(3292): FATAL EXCEPTION: main 
04-19 16:15:42.596: E/AndroidRuntime(3292): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.os.Looper.loop(Looper.java:137) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at dalvik.system.NativeStart.main(Native Method) 
04-19 16:15:42.596: E/AndroidRuntime(3292): Caused by: java.lang.NullPointerException 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at com.example.textadventure.MainActivity.onResume(MainActivity.java:31) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.Activity.performResume(Activity.java:5182) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732) 
04-19 16:15:42.596: E/AndroidRuntime(3292):  ... 12 more 
04-19 16:18:00.358: E/Trace(3350): error opening trace file: No such file or directory (2) 
04-19 16:18:01.796: D/AndroidRuntime(3350): Shutting down VM 
04-19 16:18:01.810: W/dalvikvm(3350): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
04-19 16:18:01.866: E/AndroidRuntime(3350): FATAL EXCEPTION: main 
04-19 16:18:01.866: E/AndroidRuntime(3350): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.os.Looper.loop(Looper.java:137) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at dalvik.system.NativeStart.main(Native Method) 
04-19 16:18:01.866: E/AndroidRuntime(3350): Caused by: java.lang.NullPointerException 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at com.example.textadventure.MainActivity.onResume(MainActivity.java:31) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.Activity.performResume(Activity.java:5182) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732) 
04-19 16:18:01.866: E/AndroidRuntime(3350):  ... 12 more 
04-19 16:22:06.477: E/Trace(3412): error opening trace file: No such file or directory (2) 
04-19 16:22:08.086: D/AndroidRuntime(3412): Shutting down VM 
04-19 16:22:08.116: W/dalvikvm(3412): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
04-19 16:22:08.207: E/AndroidRuntime(3412): FATAL EXCEPTION: main 
04-19 16:22:08.207: E/AndroidRuntime(3412): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.os.Looper.loop(Looper.java:137) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at dalvik.system.NativeStart.main(Native Method) 
04-19 16:22:08.207: E/AndroidRuntime(3412): Caused by: java.lang.NullPointerException 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at com.example.textadventure.MainActivity.onResume(MainActivity.java:35) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.Activity.performResume(Activity.java:5182) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732) 
04-19 16:22:08.207: E/AndroidRuntime(3412):  ... 12 more 
04-19 16:22:10.786: I/Process(3412): Sending signal. PID: 3412 SIG: 9 
04-19 16:25:22.020: D/AndroidRuntime(3477): Shutting down VM 
04-19 16:25:22.020: W/dalvikvm(3477): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
04-19 16:25:22.026: E/AndroidRuntime(3477): FATAL EXCEPTION: main 
04-19 16:25:22.026: E/AndroidRuntime(3477): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.os.Looper.loop(Looper.java:137) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at dalvik.system.NativeStart.main(Native Method) 
04-19 16:25:22.026: E/AndroidRuntime(3477): Caused by: java.lang.NullPointerException 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at com.example.textadventure.MainActivity.onResume(MainActivity.java:36) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.Activity.performResume(Activity.java:5182) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732) 
04-19 16:25:22.026: E/AndroidRuntime(3477):  ... 12 more

正如我所說的，我想是這樣的：

http://postimg.org/image/dy7g2ts6v/

我已經知道如何使按鈕切換佈局，但沒有崩潰，我不能顯示的整數。 :(

來源

2013-04-21 Dravic

+1

你確定你的佈局中有一個帶有'mytextview1'的文本視圖嗎？ – 2013-04-21 11:12:45

+0

佈局（s），因爲我現在有3個。那麼我只有其中一個mytextview1。現在我在3種不同的佈局中得到了這樣的textview。 應用程序不會顯示它沒有崩潰的整數。 – Dravic 2013-04-21 11:24:45

回答

0 
TextView tv; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    tv= (TextView) findViewById(R.id.tv); 
    //textview with id should be defined in activity_main.xml 
    //set text to textview. 
}

確保您在activity_main中有文本視圖。既然你已經設定activity_main你需要的佈局，以確保你有TextView的在activity_main

http://developer.android.com/training/basics/activity-lifecycle/starting.html

您必須實現onCreate（）方法執行應該針對整個僅出現一次基本的應用程序的啓動邏輯活動的生活。你可以在oncreate中初始化textiew。

假設活動暫停並繼續onReusme（）被調用，然後evry時間您將找到textview的id。所以在oncreate中初始化textiew。

最好開始一個新的活動或使用片段，而不是將不同的佈局設置到同一個屏幕。

activity_main

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:orientation="vertical" 
tools:context=".DisplayMessageActivity" > 

<TextView 
android:id="@+id/tv" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content"/> 
</LinearLayout>

來源

2013-04-21 11:28:24 Raghunandan

0

做這樣的：

private Integer int1 = 1;

及以下

TextView textView = (TextView) findViewById(R.id.mytextview1); 
textView.setText(int1.toString());

通知你不需要this.findViewById，只需直接使用findViewById。

來源

2013-04-21 12:04:42 pedronveloso

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