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我面临这个问题，即在给定背景时，android 中的按钮不可点击。所以，我使用了 ImageButton。 在 Java 文件中如何声明 ImageButtons？ 我在文本视图中有一个红色的 otification 徽章，我想将它放在 ImageButton 的右上角。但是textView 在按钮上不可见，即它在按钮后面隐藏了一半。解决方案是什么？

另一个问题是我的项目面临强制关闭问题。日志猫显示：

05-11 04:13:29.508: D/(3913): 在定义意图之后

05-11 04:13:29.678: D/AndroidRuntime(3913): 关闭虚拟机

05-11 04:13:29.678: W/dalvikvm(3913): threadid=1: 线程退出未捕获异常 (group=0x4001d800)

05-11 04:13:29.688：E/AndroidRuntime（3913）：致命异常：主要

05-11 04:13:29.688: E/AndroidRuntime(3913): java.lang.RuntimeException: 无法启动活动组件信息
{phone.activities/phone.activities.leave}：java.lang.NullPointerException

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.ActivityThread.access$2300(ActivityThread.java:125)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.os.Handler.dispatchMessage(Handler.java:99)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.os.Looper.loop(Looper.java:123)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.ActivityThread.main(ActivityThread.java:4627)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 java.lang.reflect.Method.invokeNative(Native Method)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 java.lang.reflect.Method.invoke(Method.java:521)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)

05-11 04:13:29.688: E/AndroidRuntime(3913): at dalvik.system.NativeStart.main(Native Method)

05-11 04:13:29.688: E/AndroidRuntime(3913): 由: java.lang.NullPointerException 引起

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 phone.activities.leave.onCreate(leave.java:33)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

05-11 04:13:29.688: E/AndroidRuntime(3913): 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

05-11 04:13:29.688: E/AndroidRuntime(3913): ... 11 更多

强制关闭的原因是什么？

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="right"
android:orientation="vertical" android:clickable="true">

<LinearLayout
    android:id="@+id/linearLayout1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:gravity="center"
        android:paddingLeft="90dp"
        android:paddingRight="58dp"
        android:text="eApproval"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textSize="22dp"
        android:textStyle="bold"
        android:typeface="sans" />
</LinearLayout>


<TableLayout
    android:id="@+id/tableLeft"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="left"
    android:paddingLeft="20dp"
    android:paddingRight="30dp"
    android:paddingTop="25dp" >



    <TableRow
        android:layout_width="match_parent"
        android:layout_height="match_parent">
<RelativeLayout android:layout_marginLeft="10dp">


    <Button
        android:id="@+id/buttonLeave"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="10dp"
        android:clickable="true"
      />


 <TextView
 android:id="@+id/textOne"
 android:layout_width="30dp"
 android:layout_height="30dp"
 android:layout_marginLeft="70dp"
 android:background="@drawable/picture1"
 android:gravity="center"
 android:text="5"
 android:textColor="#FFF"
 android:textSize="14dp"
 android:textStyle="bold"
 android:typeface="sans" />

</RelativeLayout>       
<RelativeLayout android:paddingLeft="20dp" android:layout_marginLeft="10dp">
<Button
        android:id="@+id/buttonTime"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="25dp"
        android:clickable="true"

        android:height="60dp"
        android:width="30dp" 
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" android:layout_marginTop="10dp" />


<TextView
android:id="@+id/textTwo"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginLeft="80dp"
android:background="@drawable/picture1"
android:gravity="center"
android:text="4"
android:textColor="#FFF"
android:textSize="14dp"
android:textStyle="bold"
android:typeface="sans" />

</RelativeLayout>

    </TableRow>
    <TableRow >
        <TextView
            android:id="@+id/textLeave"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Leave Requests"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="15dp"
            android:textStyle="normal|bold"
            android:typeface="sans"
            android:width="90dp" android:layout_marginLeft="20dp"
android:padding="5dp"
android:gravity="center"/>

         <TextView
            android:id="@+id/textTime"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Time Booking"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="15dp"
            android:textStyle="bold"
            android:typeface="sans"
            android:width="90dp" android:layout_marginLeft="50dp" android:padding="5dp" 
android:gravity="center"/>
   </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
<RelativeLayout android:layout_marginLeft="10dp">

    <Button
        android:id="@+id/buttonCart"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="20dp"

        android:height="60dp"
        android:width="30dp" 
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" android:layout_marginTop="10dp" 
android:clickable="true"/>


 <TextView
 android:id="@+id/textThree"
 android:layout_width="30dp"
 android:layout_height="30dp"
 android:layout_marginLeft="70dp"
 android:background="@drawable/picture1"
 android:gravity="center"
 android:text="2"
 android:textColor="#FFF"
 android:textSize="14dp"
 android:textStyle="bold"
 android:typeface="sans" />

</RelativeLayout>       
<RelativeLayout android:paddingLeft="20dp" android:layout_marginLeft="10dp">
<Button
        android:id="@+id/buttonInvoice"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="25dp"

        android:height="60dp"
        android:width="30dp" 
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" android:layout_marginTop="10dp" 
android:clickable="true"/>


<TextView
android:id="@+id/textFour"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginLeft="80dp"
android:background="@drawable/picture1"
android:gravity="center"
android:text="3"
android:textColor="#FFF"
android:textSize="14dp"
android:textStyle="bold"
android:typeface="sans" />

</RelativeLayout>

    </TableRow>
      <TableRow >
        <TextView
            android:id="@+id/textCart"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:clickable="false"
            android:text="Shopping Cart"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="15dp"
            android:textStyle="bold"
            android:typeface="sans"
            android:width="90dp" android:layout_marginLeft="20dp" android:padding="5dp" 
android:gravity="center"/>

         <TextView
            android:id="@+id/textInvoice"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:clickable="false"
            android:text="Invoice"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="15dp"
            android:textStyle="bold"
            android:typeface="sans"
            android:width="90dp" android:layout_marginLeft="50dp" android:padding="5dp" 
android:gravity="center"/>
   </TableRow>


    <TableRow
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
<RelativeLayout android:layout_marginLeft="10dp">

    <Button
        android:id="@+id/buttonPurchase"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="20dp"

        android:height="60dp"
        android:width="30dp" 
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" android:layout_marginTop="10dp" 
android:clickable="true"/>


 <TextView
 android:id="@+id/textFive"
 android:layout_width="30dp"
 android:layout_height="30dp"
 android:layout_marginLeft="70dp"
 android:background="@drawable/picture1"
 android:gravity="center"
 android:text="4"
 android:textColor="#FFF"
 android:textSize="14dp"
 android:textStyle="bold"
 android:typeface="sans" />

</RelativeLayout>

<RelativeLayout android:paddingLeft="20dp" android:layout_marginLeft="10dp">

<Button
    android:id="@+id/buttonTravel"
    android:layout_width="70dp"
    android:layout_height="70dp"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginBottom="5dp"
    android:layout_marginLeft="25dp"
    android:layout_marginTop="10dp"

    android:clickable="true"
    android:height="60dp"
    android:width="30dp" />


<TextView
    android:id="@+id/textSix"
    android:layout_width="30dp"
    android:layout_height="30dp"
    android:layout_marginLeft="80dp"
    android:background="@drawable/picture1"
    android:gravity="center"
    android:text="7"
    android:textColor="#FFF"
    android:textSize="14dp"
    android:textStyle="bold"
    android:typeface="sans" />

</RelativeLayout>

    </TableRow>


    <TableRow >
        <TextView
            android:id="@+id/textPurchase"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:clickable="false"
            android:text="Purchase Order"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="15dp"
            android:textStyle="bold"
            android:typeface="sans"
            android:width="90dp" android:layout_marginLeft="20dp" android:padding="5dp" 
android:gravity="center"/>

         <TextView
            android:id="@+id/textTravel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:clickable="false"
            android:text="Travel Approval"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="15dp"
            android:textStyle="bold"
            android:typeface="sans"
            android:width="90dp" android:layout_marginLeft="50dp" android:padding="5dp"
android:gravity="center"/>
   </TableRow>
</TableLayout>

</LinearLayout>

onCreate 方法是：package phone.activities；

import phone.activities.R;
import phone.activities.R.id;
import phone.activities.R.layout;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class EApprovalActivity extends Activity implements OnClickListener {
private static final String TAG = null;


/** Called when the activity is first created. */
@Override

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


    Button leaveButton;
    leaveButton = (Button)findViewById(R.id.buttonLeave);
    leaveButton.setOnClickListener(this);

    Button timeButton;
    timeButton = (Button)findViewById(R.id.buttonTime);
    timeButton.setOnClickListener(this);

    Button cartButton;
    cartButton = (Button)findViewById(R.id.buttonCart);
    cartButton.setOnClickListener(this);

    Button invoiceButton;
    invoiceButton = (Button)findViewById(R.id.buttonInvoice);
    invoiceButton.setOnClickListener(this);

    Button purchaseButton;
    purchaseButton = (Button)findViewById(R.id.buttonPurchase);
    purchaseButton.setOnClickListener(this);

    Button travelButton;
    travelButton = (Button)findViewById(R.id.buttonTravel);
    travelButton.setOnClickListener(this);

}


public void onClick(View v) {
    ComponentName cn;
    switch(v.getId())
    {
    case R.id.buttonLeave:
        Intent leaveIntent = new Intent(EApprovalActivity.this,
leave.class); 
        startActivity(leaveIntent);                 
        break;

    case R.id.buttonTime:
        Intent timeIntent = new Intent(EApprovalActivity.this,
time.class); 
        startActivity(timeIntent);                  
        break;

    case R.id.buttonCart:
        Intent cartIntent = new Intent(EApprovalActivity.this, 
cart.class); 
        startActivity(cartIntent);                  
        break;

    case R.id.buttonInvoice:
        Intent invoiceIntent = new Intent(EApprovalActivity.this, 
invoice.class); 
        startActivity(invoiceIntent);                   
        break;

    case R.id.buttonPurchase:
        Intent purchaseIntent = new Intent(EApprovalActivity.this, 
purchase.class); 
        startActivity(purchaseIntent);                  
        break;

    case R.id.buttonTravel:
        Intent travelIntent = new Intent(EApprovalActivity.this, 
travel.class); 
        startActivity(travelIntent);                    
        break;


    } Log.d(TAG,"after defining intent");
    }
}
4

1 回答 1

0

在 Java 文件中如何声明 ImageButtons？

ImageButton ib = findByViewId(R.id.yourImageButtonId);

textView 在按钮上不可见，即它在按钮后面隐藏了一半。解决方案是什么？

您可以将 Text 设置为按钮，而无需在其上放置 textview。

你也可以给一个简单的按钮一个android:drawableOnTop属性，给定的资源出现在顶部。

对于您的另一个问题：

检查 onCreate() 方法中的第 33 行。如果您无法自己找到 NullPointer，请发布它。

于 2012-05-14T10:40:50.627 回答