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java Android“不幸的是，<app>已经停止。”

1 年，1 月 Questions & Answers

我想应用程序停止了setContentView(R.layout.main);或TextState = (EditText) findViewById(R.id.TextState);或更多，但我不知道需要做什么。对不起错误的帖子，但请帮助我

\res\layout-land\main.xml:-需要一个水平接口

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
安卓:layout_width="match_parent"
安卓:layout_height="match_parent"
安卓:gravity="top"
安卓:orientation="vertical" >

<Button
安卓:id="@+id/Down"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:layout_alignParentBottom="true"
安卓:layout_alignParentLeft="true"
安卓:layout_marginBottom="22dp"
安卓:layout_marginLeft="22dp"
安卓:text="Button" />

<Button
安卓:id="@+id/Up"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:layout_above="@+id/Down"
安卓:layout_alignParentLeft="true"
安卓:layout_marginLeft="22dp"
安卓:text="Button" />

<Button
安卓:id="@+id/Left"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:layout_alignBottom="@+id/Down"
安卓:layout_alignParentRight="true"
安卓:layout_marginBottom="16dp"
安卓:layout_marginRight="111dp"
安卓:text="Button" />

<Button
安卓:id="@+id/Right"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:layout_alignBaseline="@+id/Left"
安卓:layout_alignBottom="@+id/Left"
安卓:layout_alignParentRight="true"
安卓:layout_marginRight="20dp"
安卓:text="Button" />

<TextView
    安卓:id="@+id/TextState"
    安卓:layout_width="wrap_content"
    安卓:layout_height="wrap_content"
    安卓:layout_above="@+id/Up"
    安卓:layout_centerHorizontal="true"
    安卓:text="Состояние"
    安卓:textSize="32sp" />

</RelativeLayout>

主要活动：

public class MainActivity extends Activity implements OnClickListener {
EditText TextState;
Button Up;
Button Down;
Button Left;
Button Right;
@Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

    TextState = (EditText) findViewById(R.id.TextState);

    Up = (Button) findViewById(R.id.Up);
    Down = (Button) findViewById(R.id.Down);
    Left = (Button) findViewById(R.id.Left);
    Right = (Button) findViewById(R.id.Right);

    Up.setOnClickListener(this);
    Down.setOnClickListener(this);
    Right.setOnClickListener(this);
    Left.setOnClickListener(this);
}
    @Override
    public void onClick(View v) {
         switch (v.getId()) {
            case R.id.Up:

              // TODO:
                TextState.setText("Едем вперед");

              break;
            case R.id.Down:

                  // TODO:
                TextState.setText("Едем назад");

              break;
            case R.id.Right:

                  // TODO:
                TextState.setText("Едем направо");

              break;
            case R.id.Left:

                  // TODO:
                TextState.setText("Едем налево");

              break;
            default:
              break;
    }

    }}

catlog：

12-18 20:25:44.299: D/AndroidRuntime(647): Shutting down VM
12-18 20:25:44.299: W/dalvikvm(647): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
12-18 20:25:44.319: E/AndroidRuntime(647): FATAL EXCEPTION: main
12-18 20:25:44.319: E/AndroidRuntime(647): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.app/com.example.app.MainActivity}: java.lang.NullPointerException
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.ActivityThread.access$600(ActivityThread.java:130)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.os.Handler.dispatchMessage(Handler.java:99)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.os.Looper.loop(Looper.java:137)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.ActivityThread.main(ActivityThread.java:4745)
12-18 20:25:44.319: E/AndroidRuntime(647):  at java.lang.reflect.Method.invokeNative(Native Method)
12-18 20:25:44.319: E/AndroidRuntime(647):  at java.lang.reflect.Method.invoke(Method.java:511)
12-18 20:25:44.319: E/AndroidRuntime(647):  at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
12-18 20:25:44.319: E/AndroidRuntime(647):  at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-18 20:25:44.319: E/AndroidRuntime(647):  at dalvik.system.NativeStart.main(Native Method)
12-18 20:25:44.319: E/AndroidRuntime(647): Caused by: java.lang.NullPointerException
12-18 20:25:44.319: E/AndroidRuntime(647):  at com.example.app.MainActivity.onCreate(MainActivity.java:32)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.Activity.performCreate(Activity.java:5008)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
12-18 20:25:44.319: E/AndroidRuntime(647):  at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
12-18 20:25:44.319: E/AndroidRuntime(647):  ... 11 more
12-18 20:26:10.839: I/Process(647): Sending signal. PID: 647 SIG: 9
12-18 20:26:16.799: E/Trace(662): error opening trace file: No such file or directory (2)
12-18 20:26:17.249: D/AndroidRuntime(662): Shutting down VM
12-18 20:26:17.249: W/dalvikvm(662): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
12-18 20:26:17.260: E/AndroidRuntime(662): FATAL EXCEPTION: main
12-18 20:26:17.260: E/AndroidRuntime(662): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.app/com.example.app.MainActivity}: java.lang.NullPointerException
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.ActivityThread.access$600(ActivityThread.java:130)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.os.Handler.dispatchMessage(Handler.java:99)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.os.Looper.loop(Looper.java:137)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.ActivityThread.main(ActivityThread.java:4745)
12-18 20:26:17.260: E/AndroidRuntime(662):  at java.lang.reflect.Method.invokeNative(Native Method)
12-18 20:26:17.260: E/AndroidRuntime(662):  at java.lang.reflect.Method.invoke(Method.java:511)
12-18 20:26:17.260: E/AndroidRuntime(662):  at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
12-18 20:26:17.260: E/AndroidRuntime(662):  at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-18 20:26:17.260: E/AndroidRuntime(662):  at dalvik.system.NativeStart.main(Native Method)
12-18 20:26:17.260: E/AndroidRuntime(662): Caused by: java.lang.NullPointerException
12-18 20:26:17.260: E/AndroidRuntime(662):  at com.example.app.MainActivity.onCreate(MainActivity.java:32)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.Activity.performCreate(Activity.java:5008)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
12-18 20:26:17.260: E/AndroidRuntime(662):  at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
12-18 20:26:17.260: E/AndroidRuntime(662):  ... 11 more
12-18 20:26:49.719: I/Process(662): Sending signal. PID: 662 SIG: 9

共 (4) 个答案

  1. # 1 楼答案 

    Caused by: java.lang.NullPointerException
at com.example.app.MainActivity.onCreate(MainActivity.java:32)

    只要看一下你的日志，你就会在第32行得到一个NPE。可能findViewById没有找到您的视图，并且该字段为空

  2. # 2 楼答案

    我在这里发现了你的错误


    EditText TextState;
    TextState = (EditText)findViewById(R.id.TextState)
    换成 TextView TextState;

    TextState = (TextView)findViewById(R.id.TextState)

    或者在XML文件中

    <EditText
android:id="@+id/TextState"/>
  3. # 3 楼答案

    将文本视图更改为EditText。问题解决了

  4. # 4 楼答案

    你应该在第32行找到问题所在

    com。实例应用程序。主要活动。onCreate（MainActivity.java:32）