Question

我希望找到这个问题的答案。我试图在图像按钮中插入onclick监听器以打开一个新活动，每当我将其运行到模拟器并单击图像按钮时，此消息显示“不幸的是我的应用程序已停止。”

到目前为止我只完成了2项活动，我想要发生的是当我点击图像按钮时它会转到我的活动2。

他是我的java代码的一个例子。

package com.example.chadymaebarinan.emojiexpress;

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.ImageButton;

public class HomeScreen extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home_screen);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG).setAction("Action", null).show();
            }
        });

        ImageButton clickGirl = (ImageButton)findViewById(R.id.myGirl);
        clickGirl.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                startActivity(new Intent(HomeScreen.this, Emoticon.class));
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_home_screen, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

这是emoticon.java中的代码

package com.example.chadymaebarinan.emojiexpress;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;

public class Emoticon extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_emoticon);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
}

}

并在清单文件中：

 ?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".HomeScreen"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".Emoticon"
        android:label="@string/title_activity_emoticon"
        android:theme="@style/AppTheme.NoActionBar" >

    </activity>
</application>

我尝试点击此处的图片按钮时的Logcat：

  10-24 19:47:09.202 3777-3777/? I/art: Not late-enabling -Xcheck:jni (already on)
 10-24 19:47:09.202 3777-3777/? I/art: Late-enabling JIT
 10-24 19:47:09.245 3777-3777/? I/art: JIT created with    code_cache_capacity=2MB compile_threshold=1000
 10-24 19:47:09.410 3777-3777/com.example.chadymaebarinan.emojiexpress   W/System: ClassLoader referenced unknown path:    /data/app/com.example.chadymaebarinan.emojiexpress-1/lib/x86
10-24 19:47:10.319 3777-3804/com.example.chadymaebarinan.emojiexpress D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
10-24 19:47:10.347 3777-3777/com.example.chadymaebarinan.emojiexpress D/: HostConnection::get() New Host Connection established 0xabeeaf20, tid 3777
10-24 19:47:10.540 3777-3804/com.example.chadymaebarinan.emojiexpress I/OpenGLRenderer: Initialized EGL, version 1.4
10-24 19:47:10.598 3777-3804/com.example.chadymaebarinan.emojiexpress W/EGL_emulation: eglSurfaceAttrib not implemented
10-24 19:47:10.600 3777-3804/com.example.chadymaebarinan.emojiexpress W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xabf30ae0, error=EGL_SUCCESS
10-24 19:47:13.410 3777-3777/com.example.chadymaebarinan.emojiexpress D/AndroidRuntime: Shutting down VM
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime: FATAL EXCEPTION: main
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime: Process: com.example.chadymaebarinan.emojiexpress, PID: 3777
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.chadymaebarinan.emojiexpress/com.example.chadymaebarinan.emojiexpress.Emoticon}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.support.v7.widget.Toolbar.getTitle()' on a null object reference
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.-wrap11(ActivityThread.java)
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:148)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5417)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.support.v7.widget.Toolbar.getTitle()' on a null object reference
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.support.v7.internal.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:100)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.support.v7.internal.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:93)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.support.v7.internal.app.ToolbarActionBar.<init>(ToolbarActionBar.java:78)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:206)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:99)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at com.example.chadymaebarinan.emojiexpress.Emoticon.onCreate(Emoticon.java:17)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:6237)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.-wrap11(ActivityThread.java) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:148) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5417) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
 10-24 19:49:52.102 3777-3784/com.example.chadymaebarinan.emojiexpress W/art: Suspending all threads took: 36.756ms

Answer 1

试试这段代码

 public class HomeScreen extends AppCompatActivity implements View.OnClickListener{

   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home_screen);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    ImageButton clickGirl = (ImageButton) findViewById(R.id.myGirl);
    clickGirl
}


public void onClick(View v) {
        switch (v.getId())
        {
            case R.id.fab:
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)

           break;
            case R.id.myGirl:
                Intent intent = new Intent(HomeScreen.this,Emoticon.class);
                startActivity(intent);
                finish();
        }

}

并添加Emoticon class此

Intent intent = getIntent();

Answer 2

最后在寻找解决方案2天后找到了答案。在阅读logcat之后，我发现由于我的nullpointer异常导致我的图像按钮失效的主要错误：

 10-24 19:47:13.411 3777-3777/com.example.chadymaebarinan.emojiexpress E/AndroidRuntime:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.support.v7.widget.Toolbar.getTitle()' on a null object reference

并修复了我的emoticon.class，这是一个更新版本：

 package com.example.chadymaebarinan.emojiexpress;

 import android.content.Intent;
 import android.os.Bundle;
 import android.support.design.widget.FloatingActionButton;
 import android.support.design.widget.Snackbar;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.view.View;

 public class Emoticon extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_emoticon);
    Intent intent = getIntent();
}

}

删除了导致nullpointer的工具栏和Snackbar。希望这对与我有同样问题的人有所帮助。：）

尝试插入onclicklistener，当应用程序在模拟器中运行时，它会停止。 Android Studio

2 个答案: