java-如何从一个活动导航到另一活动

概述我试图在Android应用程序的不同页面之间导航,当我运行项目时,它将带我进入“模拟器”屏幕,但出现错误消息：以下是.java中的代码@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_

我试图在Android应用程序的不同页面之间导航,当我运行项目时,它将带我进入“模拟器”屏幕,但出现错误消息：

以下是.java中的代码

@OverrIDeprotected voID onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentVIEw(R.layout.activity_main);    final Spinner spinner = (Spinner)findVIEwByID(R.ID.spinner1);    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromresource(    this, R.array.MyPictures, androID.R.layout.simple_spinner_item);    adapter.setDropDownVIEwResource(androID.R.layout.simple_spinner_dropdown_item);    spinner.setAdapter(adapter);    final button button = (button) findVIEwByID(R.ID.button02);    button.setonClickListener(new VIEw.OnClickListener(){        public voID onClick(VIEw v){            setContentVIEw(R.layout.imagevIEw);        }    });}

LogCat：

02-27 11:58:41.374: D/AndroIDRuntime(313): Shutting down VM02-27 11:58:41.374: W/dalvikvm(313): threadID=1: thread exiting with uncaught exception (group=0x4001d800)02-27 11:58:41.454: E/AndroIDRuntime(313): FATAL EXCEPTION: main02-27 11:58:41.454: E/AndroIDRuntime(313): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.MainActivity}: java.lang.NullPointerException02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2663)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.ActivityThread.access00(ActivityThread.java:125)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.os.Handler.dispatchMessage(Handler.java:99)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.os.Looper.loop(Looper.java:123)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.ActivityThread.main(ActivityThread.java:4627)02-27 11:58:41.454: E/AndroIDRuntime(313):  at java.lang.reflect.Method.invokeNative(Native Method)02-27 11:58:41.454: E/AndroIDRuntime(313):  at java.lang.reflect.Method.invoke(Method.java:521)02-27 11:58:41.454: E/AndroIDRuntime(313):  at com.androID.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)02-27 11:58:41.454: E/AndroIDRuntime(313):  at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:626)02-27 11:58:41.454: E/AndroIDRuntime(313):  at dalvik.system.NativeStart.main(Native Method)02-27 11:58:41.454: E/AndroIDRuntime(313): Caused by: java.lang.NullPointerException02-27 11:58:41.454: E/AndroIDRuntime(313):  at com.example.test.MainActivity.onCreate(MainActivity.java:29)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)02-27 11:58:41.454: E/AndroIDRuntime(313):  at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2627)02-27 11:58:41.454: E/AndroIDRuntime(313):  ... 11 more

有没有意识到的任何错误？？？

这是我的第二个项目,显示相同的错误
谢谢

解决方法:

你有

final button button = (button) findVIEwByID(R.ID.button02);    button.setonClickListener(new VIEw.OnClickListener(){        public voID onClick(VIEw v){            setContentVIEw(R.layout.imagevIEw);        }    });

删除此setContentVIEw(R.layout.imagevIEw);从按钮单击.还要删除final并全局声明微调器和按钮.

因此,您的按钮单击事件应该是这样的.

final button button = (button) findVIEwByID(R.ID.button02);        button.setonClickListener(new VIEw.OnClickListener(){            public voID onClick(VIEw v){                // Do something here            }        });

基本上,您的全部活动都是这样的.

button button;Spinner spinner; @OverrIDeprotected voID onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentVIEw(R.layout.activity_main);    spinner = (Spinner)findVIEwByID(R.ID.spinner1);    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromresource(    this, R.array.MyPictures, androID.R.layout.simple_spinner_item);    adapter.setDropDownVIEwResource(androID.R.layout.simple_spinner_dropdown_item);    spinner.setAdapter(adapter);    button = (button) findVIEwByID(R.ID.button02);    button.setonClickListener(new VIEw.OnClickListener(){        public voID onClick(VIEw v){          Intent mSignup = new Intent(activityOne.this, activityTwo.class);          startActivity(mSignup);        }    });}

如果您使用的是imagevIEw,请在onCreate方法中进行设置,然后尝试.

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