我新建了一个hellowworld不支持啊
package com.xiaogu.ui;
import android.app.Activity;
import android.os.Bundle;
import android.support.design.widget.Snackbar;
import android.view.View;
import android.widget.Button;
import com.xiaogu.R;
import butterknife.BindView;
import butterknife.ButterKnife;
public class MainActivity extends Activity {
@BindView(R.id.btn)
Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(findViewById(R.id.btn), "SnackbarClicked", Snackbar.LENGTH_SHORT).show();
}
});
}
}
10-21 14:58:30.440 18007-18007/com.xiaogu E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.xiaogu, PID: 18007
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xiaogu/com.xiaogu.ui.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.xiaogu.ui.MainActivity.onCreate(MainActivity.java:25)
at android.app.Activity.performCreate(Activity.java:6251)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
没问题的支持