如何在editText.setText（）中插入一个字符串

Question

你好我有一个问题，我把它放在标题中。我有这个例子，我从我的代码中提取

String text = "Test";
EditText editText = (EditText) findViewById(R.id.idField);
editText.setText(text);

并且我无法将int转换为charSequence我的目标是将一个字符串放入editText.setText（）;

这是我的onCreate：

    protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    try {
        fileExist();
        sessionTimeOut();
        passwordValidation(getLocalPassword());
    } catch (FileNotExistException e) {
        setLoginActivity();
    } catch (SessionTimeOutException e) {
        String text="Sometext";
        EditText editText = (EditText) findViewById(R.id.usernameField);
        setLoginActivity(R.string.sessionOut);
               editText.setText(text);


    } catch (PasswordInvalidException e) {
        setLoginActivity(R.string.criterios);
    }
    setWelcomeBackLayout();
}

该错误位于editText.setText（text）;位于

有我的错误：

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: pt.edu.es_loule, PID: 3498
              java.lang.RuntimeException: Unable to start activity ComponentInfo{pt.edu.es_loule/pt.edu.es_loule.LoginActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
                  at android.app.ActivityThread.-wrap11(Unknown Source:0)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
                  at android.os.Handler.dispatchMessage(Handler.java:106)
                  at android.os.Looper.loop(Looper.java:164)
                  at android.app.ActivityThread.main(ActivityThread.java:6494)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
               Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference
                  at pt.edu.es_loule.LoginActivity.onCreate(LoginActivity.java:46)
                  at android.app.Activity.performCreate(Activity.java:6999)
                  at android.app.Activity.performCreate(Activity.java:6990)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
                  at android.app.ActivityThread.-wrap11(Unknown Source:0) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
                  at android.os.Handler.dispatchMessage(Handler.java:106) 
                  at android.os.Looper.loop(Looper.java:164) 
                  at android.app.ActivityThread.main(ActivityThread.java:6494) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 

Answer 1

检查你的布局xml文件，你的editText变量为null，因为你的引用“idField”不正确。

在获得您的观点参考之前，不要忘记致电setContentView(R.layout.yourlayout)。

---

UPDATE

你忘了打电话给setContentView方法

 protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout_file);
  ...

Answer 2

String实现CharSequence，因此String.valueOf（aInt）确实可以作为参数。