Android 实现ButterKnife并给出NullPointer异常
我正在尝试在一个小项目中实现ButterKnife库,我的应用程序在启动时如何崩溃,详细信息: 以下是我的MainActivity.java:Android 实现ButterKnife并给出NullPointer异常,android,butterknife,Android,Butterknife,我正在尝试在一个小项目中实现ButterKnife库,我的应用程序在启动时如何崩溃,详细信息: 以下是我的MainActivity.java: package com.example.odai.playwithme; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widg
package com.example.odai.playwithme;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import butterknife.BindView;
import butterknife.ButterKnife;
public class MainActivity extends AppCompatActivity {
@BindView(R.id.hello_world) TextView hello;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
hello.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "Hello",
Toast.LENGTH_SHORT).show();
}
});
}
}
my activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.odai.playwithme.MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:id="@+id/hello_world"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
这就是每当我尝试运行我的应用程序时所遇到的错误:
05-22 20:32:52.019 24076-24076/com.example.odai.playwithme E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.odai.playwithme, PID: 24076
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.odai.playwithme/com.example.odai.playwithme.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2484)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2544)
at android.app.ActivityThread.access$900(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1394)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:168)
at android.app.ActivityThread.main(ActivityThread.java:5845)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.odai.playwithme.MainActivity.onCreate(MainActivity.java:22)
at android.app.Activity.performCreate(Activity.java:6248)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1125)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2437)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2544)
at android.app.ActivityThread.access$900(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1394)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:168)
at android.app.ActivityThread.main(ActivityThread.java:5845)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)
有什么想法吗?删除@Bindview行并执行以下操作以正确绑定元素:
不久前我也遇到过这个问题,实际上我只是再次尝试看看这是否只是一次而已。显然,较新的ButterKnife在您的
构建中需要更多的东西。gradle
:
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
}
}
apply plugin: 'com.neenbedankt.android-apt'
dependencies {
compile 'com.jakewharton:butterknife:8.0.1'
apt 'com.jakewharton:butterknife-compiler:8.0.1'
}
()试试这个。。。。。。。注射(这个);在on create methodcleaning project中,新版本的ButterKnife现在使用“绑定”而不是“注入”
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
}
}
apply plugin: 'com.neenbedankt.android-apt'
dependencies {
compile 'com.jakewharton:butterknife:8.0.1'
apt 'com.jakewharton:butterknife-compiler:8.0.1'
}