Android NPE TypeFace

Question

我从assets文件夹中为每个出现的Activity按钮设置了一个字体，我不明白为什么我在第56行得到一个NPE，这是：pswET.setTypeface(tf);我哪里错了？

04-25 18：18：49.983：E / AndroidRuntime（1853）：引起：java.lang.NullPointerException     在此处输入代码     -25 18：18：49.983：E / AndroidRuntime（1853）：at main.Login.onCreate（Login.java:56）

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    SharedPreferences sharedPrefs = getSharedPreferences("SharedPrefName", MODE_PRIVATE);
    boolean value;  
    String name = getPackageName() + "_PREFERENCES";
    SharedPreferences sp = getSharedPreferences(name, MODE_PRIVATE);
    //control if there is no password
    if (!sp.contains(Util.PREF_PSW) || "".equals(sp.getString(Util.PREF_PSW, null))) {

        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
        finish();
        //check if the key is stored yes / no for the password
    } if (value = sharedPrefs.getBoolean("check", true)) {
        setContentView(R.layout.tastiera_password);
    }else {
        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
        finish();
    }
    Typeface tf=Typeface.createFromAsset(getAssets(),"roboto.ttf");
    pswET = (TextView) findViewById(R.id.psw);
    pswET.setTypeface(tf);
    bb1 = (Button) findViewById(R.id.b1);
    bb1.setTypeface(tf);
    bb2 = (Button) findViewById(R.id.b2);
    bb2.setTypeface(tf);
    bb3 = (Button) findViewById(R.id.b3);
    bb3.setTypeface(tf);
    bb4 = (Button) findViewById(R.id.b4);
    bb4.setTypeface(tf);
    bb5 = (Button) findViewById(R.id.b5);
    bb5.setTypeface(tf);
    bb6 = (Button) findViewById(R.id.b6);
    bb6.setTypeface(tf);
    bb7 = (Button) findViewById(R.id.b7);
    bb7.setTypeface(tf);
    bb8 = (Button) findViewById(R.id.b8);
    bb8.setTypeface(tf);
    bb9 = (Button) findViewById(R.id.b9);
    bb9.setTypeface(tf);
    bb0 = (Button) findViewById(R.id.b0);
    bb0.setTypeface(tf);
      // Set the listener for all the buttons
    int numberButtons[] = { R.id.b1, R.id.b2, R.id.b3,
      R.id.b4, R.id.b5, R.id.b6, R.id.b7,
      R.id.b8, R.id.b9, R.id.b0
    };
    NumberButtonClickListener numberClickListener = new NumberButtonClickListener();
    for(int id : numberButtons) {
     View v = findViewById(id);
     v.setOnClickListener(numberClickListener);
    }
    }
private class NumberButtonClickListener implements OnClickListener {
    @Override
    public void onClick(View v)  {
        String text = (String) ((Button)v).getText();           

            setCurrentString(getCurrentString()+text);

    }
     public void setCurrentString(String s) {
            currentString = s;
            pswET.setText(s);
        }
        public String getCurrentString() {
            return currentString;
        }

}

Answer 1

您的findViewById失败，原因是您没有设置内容视图，或者因为您使用的是不存在的ID。请记住，finish（）不会结束函数的执行 - 需要返回，所以如果你进入if / else的那个分支，你将永远不会发送内容视图，findViewById将始终返回null