我正在制作一个Android应用程序，最初用户获得了＃34; GO＆＃34;按钮。单击按钮时，可以看到一个新的相对布局，其中有几个选项按钮，即＆＃34;添加＆＃34;和＆＃34;减法＆＃34;。 然后，我尝试获取用户点击的按钮，并相应地显示该组问题。 但是，只要单击GO按钮，应用程序就会崩溃。 我的代码检查点击了哪个按钮---
public void start(View view)
{
startbutton.setVisibility(View.INVISIBLE);
Log.i("YO:", "Start button ok!");
optionRelativeLayout.setVisibility(RelativeLayout.VISIBLE);
int tag = (Integer) view.getTag();
if(tag==4)
additionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
if(tag==5)
subtractionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
}
XML代码
<Button
android:text="Go!"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:id="@+id/start_button"
android:textSize="80sp"
android:paddingBottom="50dp"
android:paddingEnd="50dp"
android:paddingLeft="50dp"
android:paddingRight="50dp"
android:paddingStart="50dp"
android:paddingTop="50dp"
android:background="@android:color/holo_green_light"
android:onClick="start"
android:visibility="visible" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/optionrelativlayout"
android:visibility="visible">
<Button
android:text="Addition"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:tag="4 "
android:layout_centerHorizontal="true"
android:layout_marginTop="45dp"
android:id="@+id/addition" />
<Button
android:text="Button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:tag="5"
android:layout_centerHorizontal="true"
android:id="@+id/subtraction"
android:layout_marginTop="150dp" />
</RelativeLayout>
错误是
04-24 22:21:39.525 10853-10853/com.example.rohit_136.brain_trainer I/YO:: Start button ok!
04-24 22:21:39.527 10853-10853/com.example.rohit_136.brain_trainer E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.rohit_136.brain_trainer, PID: 10853
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:5226)
at android.view.View$PerformClick.run(View.java:21350)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5582)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5226)
at android.view.View$PerformClick.run(View.java:21350)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5582)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Integer.intValue()' on a null object reference
at com.example.rohit_136.brain_trainer.MainActivity.start(MainActivity.java:177)
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5226)
at android.view.View$PerformClick.run(View.java:21350)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5582)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
04-24 22:21:39.535 10853-10865/com.example.rohit_136.brain_trainer I/ActivityThreadEui: schedulePauseActivity com.example.rohit_136.brain_trainer.MainActivity finished=true userLeaving=false configChanges=0 dontReport=false
04-24 22:21:41.098 10853-10853/com.example.rohit_136.brain_trainer I/Process: Sending signal. PID: 10853 SIG: 9
答案 0 :(得分：2)
为什么不使用这些按钮已有的ID？
public void start(View view)
{
startbutton.setVisibility(View.INVISIBLE);
Log.i("YO:", "Start button ok!");
optionRelativeLayout.setVisibility(RelativeLayout.VISIBLE);
int id = view.getId();
if(id==R.id.addition)
additionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
if(id==R.id.subtraction)
subtractionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
}
答案 1 :(得分：2)
- 编辑 -
我想我没理解你想要达到的目标。
1 - 在您的start()方法中，将其删除：
int tag = (Integer) view.getTag();
if(tag==4)
additionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
if(tag==5)
subtractionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
2 - 创建两个新方法并将可见性线放入其中：
public void displayAddition(View view){
additionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
}
public void displaySubtraction(View view){
subtractionrelativelayout.setVisibility(RelativeLayout.VISIBLE);
}
3 - 在XML中，将它们添加到按钮：
在addition按钮中添加以下行：
android:onClick="displayAddition"
在subtraction按钮中添加以下行：
android:onClick="displaySubtraction"
答案 2 :(得分：0)
您正在使用view.getTag()，但问题是视图不是按钮变量
使用此：
Button button = (Button) view;
int Tag = button.getTag();
//Do what ever you wanna do with the tag from here on...
希望这会有所帮助