java - 带有 NullPointerException 的新 onClickListener (Android)

Question

我在运行时使用 onClickListeners 创建了一些 textView。

但是我得到了一个NullPointer..。我认为原因是View，他不知道textView应该在哪里。

我该如何解决这个问题？

ShowSomething 类中有趣的几行代码:

textView.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {

        Toast.makeText(ShowSomething.this, textView.getText().toString(), Toast.LENGTH_LONG).show();
        }
    });
    layout.addView(t);

完整类ShowSomething:

public class ShowSomething extends Activity {

    public void showData(final String[][] array, final int i, int j, LinearLayout layout, final TextView t, TextView t2, int color) {
        String Text = null;
        int size = 12;
        int top = 0;
        int bot = 0;

        if (j == 0) {
            size = 14;
            Text = array[j][i];
            top = 5;
            bot = 0;

        }
        if (j == 1) {
            size = 10;
            Text = "  " + array[j][i];
            top = 5;
            bot = 5;
        }
        t.setTextSize(TypedValue.COMPLEX_UNIT_DIP, size);
        t.setTextColor(color);
        t.setPadding(0, top, 0, bot);
        t.setClickable(false);
        t.setText(Text);
        t.setId(j + i);
        t.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                Toast.makeText(ShowSomething.this, t.getText().toString(), Toast.LENGTH_LONG).show();
            }
        });
        layout.addView(t);
    }
}

类ProjectsActivity中有趣的几行:

    setContentView(R.layout.activity_projects);
    int j = 0;
    //result    
    for (i = 0; i < array[0].length; i++) {
        while (j <2) {
            LinearLayout layout = (LinearLayout) findViewById(R.id.mainLayout);
            final TextView t = new TextView(getApplicationContext());
            final TextView t2 = new TextView(getApplicationContext());
            ShowSomething.showData(array, i, j, layout, t, t2, color);

完整类ProjectsActivity:

public class ProjectsActivity extends Activity {
public String[][] array = null;
public int i = 0;
int color;
ShowSomething show = new ShowSomething();
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_projects);

    int j = 0;

    array = Connect.printJobList();

    for (i = 0; i < array[0].length; i++) {
        while (j < 2) {
            LinearLayout layout = (LinearLayout) findViewById(R.id.mainLayout);
            final TextView t = new TextView(getApplicationContext());
            final TextView t2 = new TextView(getApplicationContext());

            if (j == 0){    
                color = getResources().getColor(R.color.Project1);
            }
            if (j == 1){
                color = getResources().getColor(R.color.Project2);
            }

            show.showData(array, i, j, layout, t, t2, color);
            if (j == 1){
                t2.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, 1));
                t2.setBackgroundColor(getResources().getColor(R.color.Line));
                layout.addView(t2);
            }
            j++;
        }
        j = 0;
    }       
}

}

LogCat:

03-26 08:19:38.294: D/AndroidRuntime(1991): Shutting down VM
03-26 08:19:38.294: W/dalvikvm(1991):       threadid=1: thread exiting with uncaught exception (group=0x414c4700)
03-26 08:19:38.332: E/AndroidRuntime(1991): FATAL EXCEPTION: main
03-26 08:19:38.332: E/AndroidRuntime(1991): java.lang.NullPointerException
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.app.Activity.setContentView(Activity.java:1895)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at de.xcom.mobilenav.ShowSomething$1.onClick(ShowSomething.java:47)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.view.View.performClick(View.java:4240)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.view.View$PerformClick.run(View.java:17721)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.os.Handler.handleCallback(Handler.java:730)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.os.Looper.loop(Looper.java:137)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at android.app.ActivityThread.main(ActivityThread.java:5103)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at java.lang.reflect.Method.invokeNative(Native Method)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at java.lang.reflect.Method.invoke(Method.java:525)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-26 08:19:38.332: E/AndroidRuntime(1991):     at dalvik.system.NativeStart.main(Native Method)

ShowSomething第47行:(忽略注释)

43 public void onClick(View v) { 
44 //Intent intent = new Intent(ShowSomething.this, ProjectDetailActivity.class); 
45 //intent.putExtra("Project", array[0][i]); 
46   
47 //startActivity(intent); 
48 
49 Toast.makeText(ShowSomething.this, t.getText().toString(), Toast.LENGTH_LONG).show();

更改了类ShowSomething:

public class ShowSomething {
.
.
.   t.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        Intent intent = new Intent(ShowSomething.this, ProjectDetailActivity.class);
        intent.putExtra("Project", array[0][i]);

        startActivity(intent);

        //Toast.makeText(getApplicationContext() , t.getText().toString(), Toast.LENGTH_LONG).show();
        }
    });

但现在我收到一个错误:构造函数 Intent(ShowSomething, Class) 未定义...

Answer 1

ShowSomething show = new ShowSomething();

您无法使用new实例化 Activity 。

看起来 ShowSomething 根本不应该是一个 Activity 。例如，您可以将 Context 作为方法参数传递给它。

要将数据从一个 Activity 传递到另一个 Activity ，请使用 Intent 。请参阅How do I pass data between Activities in Android application?