如何解决不支持图标和文本更改设置的操作栏？

Question

我无法调试这个 problem.i.e.when 我正在尝试更改文本名称并为它不支持的操作栏放置一个图标..我的意思是它会抛出类似

的错误

02-06 11:43:39.964 9510-9510/com.example.brahmaiah.app1_menu E/AndroidRuntime: FATAL EXCEPTION: main
                                                                               Process: com.example.brahmaiah.app1_menu, PID: 9510
                                                                               java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.brahmaiah.app1_menu/com.example.brahmaiah.app1_menu.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setIcon(int)' on a null object reference
                                                                                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
                                                                                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
                                                                                   at android.app.ActivityThread.access0(ActivityThread.java:151)
                                                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
                                                                                   at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                   at android.os.Looper.loop(Looper.java:135)
                                                                                   at android.app.ActivityThread.main(ActivityThread.java:5257)
                                                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                                                   at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
                                                                                Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setIcon(int)' on a null object reference
                                                                                   at com.example.brahmaiah.app1_menu.MainActivity.onCreate(MainActivity.java:20)
                                                                                   at android.app.Activity.performCreate(Activity.java:5990)
                                                                                   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
                                                                                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
                                                                                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390) 
                                                                                   at android.app.ActivityThread.access0(ActivityThread.java:151) 
                                                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
                                                                                   at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                                   at android.os.Looper.loop(Looper.java:135) 
                                                                                   at android.app.ActivityThread.main(ActivityThread.java:5257) 
                                                                                   at java.lang.reflect.Method.invoke(Native Method) 
                                                                                   at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
                                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

我的MainActivity.java

@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.content_main);
    android.support.v7.app.ActionBar actionBar=getSupportActionBar();
    actionBar.setIcon(R.drawable.ic_image3);
    Toolbar toolbar = (Toolbar) findViewById(R.id.my_toolbar);
    setSupportActionBar(toolbar);

并且我支持 v 7 和 v 4 libraries.i 我也尝试在我的 activityi.e.actionBar.getSupportActionBar(); 中执行这样的操作。请帮助我摆脱它的调试。我认为不需要 manifest.xml..因为我用 minversion:7 和 maxVersion17 正确标记了..提前谢谢！！和应用主题也喜欢...light.noActionBar

Answer 1

使用AppCompatActivity

import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;

试试这个代码：

final ActionBar actionBar = getSupportActionBar();
    actionBar.setDisplayHomeAsUpEnabled(true);
    actionBar.setHomeAsUpIndicator(R.drawable.back_dark);
    actionBar.setTitle(getResources().getString(R.string.title));

Answer 2

您需要先将 Toolbar 设置为操作栏，然后再使用 getSupportActionBar()

您需要更改以下代码

android.support.v7.app.ActionBar actionBar=getSupportActionBar();
actionBar.setIcon(R.drawable.ic_image3);
Toolbar toolbar = (Toolbar) findViewById(R.id.my_toolbar);
setSupportActionBar(toolbar);

到

Toolbar toolbar = (Toolbar) findViewById(R.id.my_toolbar);
setSupportActionBar(toolbar);
android.support.v7.app.ActionBar actionBar=getSupportActionBar();
actionBar.setIcon(R.drawable.ic_image3);

如何解决不支持图标和文本更改设置的操作栏？

how to resolve action bar not supporting for icon and text change setup?

android

android-actionbar

android-menu