我想通过按钮登录从主要 Activity 更改为登录 Activity 。我遵循了所有步骤,但当我在我的设备上测试它时它仍然不起作用。
这是main.java:
公共(public)类 MainActivity 扩展 AppCompatActivity 实现 View.OnClickListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
View v = findViewById(R.id.buttonlog);
v.setOnClickListener((View.OnClickListener) this);
}
@Override
public void onClick(View v) {
if(v.getId()==R.id.buttonlog)
{
Intent intent = new Intent(this,LoginActivity.class);
this.startActivity(intent);
}
}}
登录 Activity 是:
public class LoginActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
}
}
Logcat:
12-06 19:57:03.960 6374-6374/com.example.ancaalexandra.proiectandroidd D/ViewRootImpl@c94e23f[MainActivity]: ViewPostImeInputStage processPointer 0
12-06 19:57:03.961 6374-6374/com.example.ancaalexandra.proiectandroidd E/BoostFramework: BoostFramework() : Exception_1 = java.lang.ClassNotFoundException: Didn't find class "com.qualcomm.qti.Performance" on path: DexPathList[[],nativeLibraryDirectories=[/system/lib64, /vendor/lib64]]
12-06 19:57:03.961 6374-6374/com.example.ancaalexandra.proiectandroidd V/BoostFramework: BoostFramework() : mPerf = null
12-06 19:57:04.046 6374-6374/com.example.ancaalexandra.proiectandroidd D/ViewRootImpl@c94e23f[MainActivity]: ViewPostImeInputStage processPointer 1
12-06 19:57:04.435 6374-6374/com.example.ancaalexandra.proiectandroidd D/ViewRootImpl@c94e23f[MainActivity]: ViewPostImeInputStage processPointer 0
12-06 19:57:04.522 6374-6374/com.example.ancaalexandra.proiectandroidd D/ViewRootImpl@c94e23f[MainActivity]: ViewPostImeInputStage processPointer 1
12-06 19:57:04.791 6374-6374/com.example.ancaalexandra.proiectandroidd D/ViewRootImpl@c94e23f[MainActivity]: MSG_WINDOW_FOCUS_CHANGED 0
12-06 19:57:04.837 6374-6374/com.example.ancaalexandra.proiectandroidd D/AndroidRuntime: Shutting down VM
12-06 19:57:04.838 6374-6374/com.example.ancaalexandra.proiectandroidd E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ancaalexandra.proiectandroidd, PID: 6374
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ancaalexandra.proiectandroidd/com.example.ancaalexandra.proiectandroidd.LoginActivity}: java.lang.ClassCastException: com.example.ancaalexandra.proiectandroidd.LoginActivity cannot be cast to android.view.View$OnClickListener
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2984)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)
Caused by: java.lang.ClassCastException: com.example.ancaalexandra.proiectandroidd.LoginActivity cannot be cast to android.view.View$OnClickListener
at com.example.ancaalexandra.proiectandroidd.LoginActivity.onCreate(LoginActivity.java:19)
at android.app.Activity.performCreate(Activity.java:6956)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1126)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2927)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)
我在 list 文件中声明了这两项 Activity 。我做错了什么?谢谢!
最佳答案
您处理 findViewById() 和设置 onClick 监听器的方式非常不寻常。
更改此代码:
View v = findViewById(R.id.buttonlog);
v.setOnClickListener((View.OnClickListener) this);
这段代码:
Button loginButton = (Button)findViewById(R.id.buttonlog);
loginButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,LoginActivity.class);
startActivity(intent);
}
});
它应该可以正常工作。
关于java - 无法更改至其他 Activity ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47680672/