android - 模拟器不在按钮上显示图像单击android

Question

请多多包涵，我是 Android 编程的新手。我试图在 android 中单击按钮时显示图像，但不幸的是我的模拟器没有显示所需的输出。这是我的 layout.xml 文件

<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=".MainActivity" >


<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_below="@+id/textView1"
    android:layout_marginTop="14dp"
    android:text="Button" />

</RelativeLayout>

main_activity.java

package com.example.app1;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.Button;
import android.widget.ImageView;
import android.view.View;
import android.view.View.OnClickListener;

public class MainActivity extends Activity {
Button button;
ImageView image;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
         }


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


public void addListenerOnButton() {

    button = (Button) findViewById(R.id.button1);

    button.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {


                  image.setImageResource(R.drawable.optimus);

        }

    });


}   

我已将图像文件包含在/res/drawable-mdpi 下。当我尝试在模拟器上运行时，它不会在单击按钮时显示图像。代码有问题吗？

Answer 1

请在您的 onCreate() 方法中写下:

Button theButton = (Button)findViewById(R.id.button1);
theButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // TODO Auto-generated method stub

theButton.setBackgroundResource(R.drawable.optimus);
        }