非靜態setGravity不能從靜態上下文中引用

Question

我對android開發非常陌生，但知道一點Java。我有問題知道在我的代碼中放置Toast.setGravity（Gravity.TOP，0,0）的位置。

下面的代碼：

package ca.ignitestudio.geoquiz; 

import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.Gravity; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 


public class QuizActivity extends AppCompatActivity { 

private Button mTrueButton; 
private Button mFalseButton; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_quiz); 



    mTrueButton = (Button) findViewById(R.id.true_button); 
    mTrueButton.setOnClickListener(new View.OnClickListener(){ 
     @Override 
     public void onClick(View v) { 
      Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show(); 
      Toast.setGravity(Gravity.TOP,0,0); 
     } 
    }); 
    mFalseButton = (Button) findViewById(R.id.false_button); 
    mFalseButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      Toast.makeText(QuizActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show(); 
     } 
    }); 
} 

}

Answer 1

你將不得不調用setGravity這樣：

Toast toast = Toast.makeText(test.this,"bbb", Toast.LENGTH_LONG); 
    toast.setGravity(Gravity.CENTER, 0, 0); 
    toast.show(); 

Answer 2

setGravity是不是一個靜態方法，所以你應該叫setGravity你吐司實例，即

Toast t = Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT); 
t.setGravity(Gravity.TOP,0,0); 
t.show(); 

Answer 3

您需要在實例上調用setGravity()，而不是在類上。更改

Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show(); 
Toast.setGravity(Gravity.TOP,0,0); 

到

Toast toast = Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT); 
toast.setGravity(Gravity.TOP,0,0); 
toast.show();