好的，我正在构建一个有24个问题的应用程序，每个问题在24个布局中有4个答案和按钮在24布局有相同的id和点击值，我试图计数每一个按钮点击24布局和最后的布局显示每个按钮点击的结果，但在最后的布局应用程序崩溃下面是我使用的代码
package com.example.andoid.disctest;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivityresult extends AppCompatActivity {
TextView txtCount;
Button btnCount;
int count = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activityresult);
txtCount = (TextView)findViewById(R.id.d_result);
btnCount.findViewById(R.id.button_d);
btnCount.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
count ++;
txtCount.setText(String.valueOf(count));
}
});
}
}
12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: FATAL EXCEPTION: main12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: Process: com.example.andoid。磁盘，PID: 1318812-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.andoid.disctest/com.example.andoid.disctest. com.example.andoid.disctest. comMainActivity_result}: java.lang.NullPointerException12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2413)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)12-27 20:56:54.169 13188-13188/com.example.andoid。在android.app.ActivityThread.access$900(ActivityThread.java:175)12-27 20:56:54.169 13188-13188/com.example.andoid。在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.os. loop .loop(loop .java:146)12-27 20:56:54.169 13188-13188/com.example.andoid。在android.app.ActivityThread.main(ActivityThread.java:5602)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at java.lang.reflect.Method。invokeNative(本地方法)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:515)12-27 20:56:54.169 13188-13188/com.example.andoid。//AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime:在dalvik.system. native . art。主要(本地方法)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: Caused by: java.lang.NullPointerException12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at com.example.andoid.disctest.MainActivity_result.onCreate(MainActivity_result.java:24)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.app.Activity.performCreate(Activity.java:5451)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)12-27 20:56:54.169 13188-13188/com.example.andoid。在android.app.ActivityThread.access$900(ActivityThread.java:175)12-27 20:56:54.169 13188-13188/com.example.andoid。在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at android.os. loop .loop(loop .java:146)12-27 20:56:54.169 13188-13188/com.example.andoid。在android.app.ActivityThread.main(ActivityThread.java:5602)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at java.lang.reflect.Method。invokeNative(本地方法)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:515)12-27 20:56:54.169 13188-13188/com.example.andoid。//AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)12-27 20:56:54.169 13188-13188/com.example.andoid。disctest E/AndroidRuntime:在dalvik.system. native . art。main(Native Method)
btnCount未初始化。你应该替换:
btnCount.findViewById(R.id.button_d);
:
btnCount = (Button)findViewById(R.id.button_d);