Android的TabHost.addTab - ＆GT;空指针异常 [英] Android TabHost.addTab -> Null pointer exception

问题描述

下面是我的code：

    public class Main extends Activity {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            TabHost tabHost = new TabHost(this);

            TabHost.TabSpec tab = tabHost.newTabSpec("tab1");
            tab.setIndicator("Tab 1");
            tab.setContent(new TabHost.TabContentFactory() {
                @Override
                public View createTabContent(String tag) {
                    TextView tv = new TextView(Main.this);
                    tv.setText("tab 1 content");
                    return tv;
                }
            });

            tabHost.addTab(tab);

            setContentView(tabHost);
        }
    }

我得到这个错误：

I get this error:

    [...]
    07-13 20:26:49.261: ERROR/AndroidRuntime(625): Caused by: java.lang.NullPointerException
    07-13 20:26:49.261: ERROR/AndroidRuntime(625):     at android.widget.TabHost.addTab(TabHost.java:206)
    07-13 20:26:49.261: ERROR/AndroidRuntime(625):     at test.test.Main.onCreate(Main.java:27)
    [...]

我需要code做到这一点，我不能使用XML。谁能帮我解决这个问题code吗？

I need to do this by code and I can't use XML. Can anyone help me fix this code please ?

推荐答案

您应该使用TabActivity，它需要相同的特殊布局设置为内容（见<一href="http://developer.android.com/resources/tutorials/views/hello-tabwidget.html">http://developer.android.com/resources/tutorials/views/hello-tabwidget.html).如果你不能使用XML，你应该建立在Java code相同的内容：

You should use TabActivity, it needs same special layout to be set as content (see http://developer.android.com/resources/tutorials/views/hello-tabwidget.html). If you can not use xml you should construct the same content from java code:

public class Main extends TabActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    TabHost tabHost = new TabHost(this);
    tabHost.setId(android.R.id.tabhost);

    TabWidget widget = new TabWidget(this);
    widget.setId(android.R.id.tabs);

    FrameLayout content = new FrameLayout(this);
    content.setId(android.R.id.tabcontent);

    LinearLayout layout = new LinearLayout(this);
    layout.setOrientation(LinearLayout.VERTICAL);
    layout.addView(widget);
    layout.addView(content);

    tabHost.addView(layout);

    setContentView(tabHost);

    TabHost.TabSpec tab1 = tabHost.newTabSpec("tab1");
    tab1.setIndicator("Tab 1");
    tab1.setContent(new TabHost.TabContentFactory() {
        @Override
        public View createTabContent(String tag) {
            TextView tv = new TextView(Main.this);
            tv.setText("tab 1 content");
            return tv;
        }
    });

    tabHost.addTab(tab1);

    TabHost.TabSpec tab2 = tabHost.newTabSpec("tab2");
    tab2.setIndicator("Tab 2");
    tab2.setContent(new TabHost.TabContentFactory() {
        @Override
        public View createTabContent(String tag) {
            TextView tv = new TextView(Main.this);
            tv.setText("tab 2 content");
            return tv;
        }
    });

    tabHost.addTab(tab2);

    setContentView(tabHost);
}

}

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