不幸的是，应用程序已停止工作-android emulator

我是android应用程序开发新手。在学习应用程序开发时，我遇到了一个错误：

不幸的是，应用程序已停止工作

我的应用程序正常打开，但当我右键输入文本并单击按钮时，它停止工作，并显示上述错误。}

TextPlay.java：

import android.widget.EditText;
import android.widget.TextView;
import android.widget.ToggleButton;

public class TextPlay extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.text);
        Button ChkCmd = (Button) findViewById(R.id.bResults);
        final ToggleButton passTog = (ToggleButton) findViewById(R.id.tbPassword);
        final EditText input = (EditText) findViewById(R.id.etCommands);
        final TextView display = (TextView) findViewById(R.id.tvDisplay);
        passTog.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if (passTog.isChecked()) {
                    input.setInputType(InputType.TYPE_CLASS_TEXT
                            | InputType.TYPE_TEXT_VARIATION_PASSWORD);
                } else {
                    input.setInputType(InputType.TYPE_CLASS_TEXT);
                }

            }

        });
        ChkCmd.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String check = input.getText().toString();
                if (check.contentEquals("left")) {
                    display.setGravity(Gravity.LEFT);
                } else if (check.contentEquals("right")) {
                    display.setGravity(Gravity.CENTER);
                } else if (check.contentEquals("center")) {
                    display.setGravity(Gravity.RIGHT);
                } else if (check.contentEquals("blue")) {

                }

            }
        });

    }

}

这是我的MainFest:

        <?xml version="1.0" encoding="utf-8"?>
        <manifest xmlns:android="http://schemas.android.com/apk/res/android"
            package="com.example.dikshant"
            android:versionCode="1"
            android:versionName="1.0" >

            <uses-sdk
                android:minSdkVersion="8"
                android:targetSdkVersion="21" />

            <application
                android:allowBackup="true"
                android:icon="@drawable/ic_launcher"
                android:label="@string/app_name"
                android:theme="@style/AppTheme" >
                <activity
                    android:name=".Splash"
                    android:label="@string/app_name" >
                    <intent-filter>
                        <action android:name="android.intent.action.MAIN" />
                        <category android:name="android.intent.category.LAUNCHER" />
                    </intent-filter>
                </activity>
                <activity
                    android:name=".MainActivity"
                    android:label="@string/app_name" >
                    <intent-filter>
                        <action android:name="com.example.dikshant.MAINACTIVITY" />

                        <category android:name="android.intent.category.DEFAULT" />
                    </intent-filter>
                </activity>
                 <activity
                    android:name=".Menu"
                    android:label="@string/app_name" >
                    <intent-filter>
                        <action android:name="com.example.dikshant.MENU" />

                        <category android:name="android.intent.category.DEFAULT" />
                    </intent-filter>
                </activity>
                    <activity
                    android:name=".TextPlay"
                    android:label="@string/app_name" >
                    <intent-filter>
                        <action android:name="com.example.dikshant.TEXTPLAY" />
                        <category android:name="android.intent.category.DEFAULT" />
                    </intent-filter>
                </activity>
            </application>

        </manifest>

    ---------------------------------------------------------------------------------

--->>从现在起出现红色突出显示的错误：

07-16 21:09:00.576: E/AndroidRuntime(1906): FATAL EXCEPTION: main
07-16 21:09:00.576: E/AndroidRuntime(1906): Process: com.example.dikshant, PID: 1906
07-16 21:09:00.576: E/AndroidRuntime(1906): java.lang.NullPointerException
07-16 21:09:00.576: E/AndroidRuntime(1906):     at com.example.dikshant.TextPlay$2.onClick(TextPlay.java:51)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.view.View.performClick(View.java:4438)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.view.View$PerformClick.run(View.java:18422)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.os.Handler.handleCallback(Handler.java:733)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.os.Handler.dispatchMessage(Handler.java:95)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.os.Looper.loop(Looper.java:136)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.app.ActivityThread.main(ActivityThread.java:5017)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at java.lang.reflect.Method.invokeNative(Native Method)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at java.lang.reflect.Method.invoke(Method.java:515)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at dalvik.system.NativeStart.main(Native Method)

---

在代码中，您将错误的id与

TextView

关联

 final TextView display=(TextView)findViewById(R.id.tvDisplay);

它应该是

R.id.tvResults

，就像您在布局中定义的那样

---

只要更改它，您的代码就会运行ok:D

请显示StackTrace。你犯了什么错误？在哪一行？红色突出显示了LOGCAT 07-16 21:09:00.396中的错误：W/dalvikvm（1906）：threadid=1：线程以未捕获异常退出（group=0xb1ac2ba8）07-16 21:09:00.576:E/AndroidRuntime（1906）：致命异常：main 07-16 21:09:00.576:E/AndroidRuntime（1906）：进程：com.example.dikshant，PID:1906 07-16 21:09:00.576:E/AndroidRuntime（1906）：java.lang.NullPointerException 07-16 21:09:00.576:E/AndroidRuntime（1906）：在com.example.dikshant.TextPlay$2.onClick（TextPlay.java:51）07-16 21:09:00.576:E/AndroidRuntime（1906）：在android.view.view.performClick（view.java:4438）用完整堆栈跟踪编辑您的问题，而不是注释，拜托，是在你的TextPlay.java第51行你的应用程序崩溃了吗？那一行是什么？是的，它在TextPlay.java中，我想nd代码-->字符串检查=input.getText（）.toString（）；if（check.contentEquals（“左”）{display.setGravity（Gravity.left）；}else if（check.contentEquals（“右”）{display.setGravity（Gravity.CENTER）；}else if（check.contentEquals（“蓝色”）{

07-16 21:09:00.576: E/AndroidRuntime(1906): FATAL EXCEPTION: main
07-16 21:09:00.576: E/AndroidRuntime(1906): Process: com.example.dikshant, PID: 1906
07-16 21:09:00.576: E/AndroidRuntime(1906): java.lang.NullPointerException
07-16 21:09:00.576: E/AndroidRuntime(1906):     at com.example.dikshant.TextPlay$2.onClick(TextPlay.java:51)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.view.View.performClick(View.java:4438)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.view.View$PerformClick.run(View.java:18422)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.os.Handler.handleCallback(Handler.java:733)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.os.Handler.dispatchMessage(Handler.java:95)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.os.Looper.loop(Looper.java:136)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at android.app.ActivityThread.main(ActivityThread.java:5017)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at java.lang.reflect.Method.invokeNative(Native Method)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at java.lang.reflect.Method.invoke(Method.java:515)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-16 21:09:00.576: E/AndroidRuntime(1906):     at dalvik.system.NativeStart.main(Native Method)

 final TextView display=(TextView)findViewById(R.id.tvDisplay);