如何以编程方式更改ActionBar中的MenuItem图标？我试着用
MenuItem menuItem = (MenuItem)findViewById(R.id.action_settings);
menuItem.setIcon(getResources().getDrawable(R.drawable.ic_launcher))
但它不起作用.
这是我的代码：
主要活动
package com.test;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
private Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
MenuItem menuItem = (MenuItem)findViewById(R.id.action_settings);
menuItem.setIcon(getResources().getDrawable(R.drawable.ic_launcher));
}
});
}
@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;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
main.xml中
xmlns:android="/apk/res/android"
xmlns:app="/apk/res-auto"
xmlns:tools="/tools"
tools:context=".MainActivity" >
android:icon="@drawable/action_settings"
android:id="@+id/action_settings"
android:title="@string/action_settings"
android:orderInCategory="100"
app:showAsAction="always"/>
activity_main
xmlns:android="/apk/res/android"
android:layout_height="fill_parent"
android:layout_width="fill_parent">
android:id="@+id/button"
android:text="Set icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
这是我跑完后的例外：
MenuItem menuItem = (MenuItem)findViewById(R.id.action_settings);
11-09 19:52:40.471 1735-1735/com.test E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.ClassCastException: android.support.v7.internal.view.menu.ActionMenuItemView
at com.test.MainActivity$1.onClick(MainActivity.java:19)
at android.view.View.performClick(View.java:2485)
at android.view.View$PerformClick.run(View.java:9080)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3683)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)
解决方法:
您不能在onCreate()的菜单项上使用findViewById(),因为菜单布局尚未膨胀.您可以创建一个全局Menu变量并在onCreateOptionsMenu()中初始化它,然后在onClick()中使用它.
private Menu menu;
在你的onCreateOptionsMenu()中
this.menu = menu;
在按钮的onClick()方法中
menu.getItem(0).setIcon(ContextCompat.getDrawable(this, R.drawable.ic_launcher));
标签：android,java
来源： https://codeday.me/bug/0923/1814909.html
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